Cisco IOS Switching Services Configuration Guide · Cisco IOS Switching Services Configuration Guide About Cisco IOS Software Documentation xxiii Documentation Objectives xxiii Audience

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C O N T E N T S

iiiCisco IOS Switching Services Configuration Guide

About Cisco IOS Software Documentation xxiii

Documentation Objectives xxiii

Audience xxiii

Documentation Organization xxiii

Documentation Modules xxiii

Master Indexes xxvi

Supporting Documents and Resources xxvi

New and Changed Information xxvi

Document Conventions xxvii

Command Syntax Conventions xxviii

Cisco.com xxviii

World Wide Web xxviii

Documentation CD-ROM xxix

Ordering Documentation xxix

Documentation Feedback xxix

Using Cisco IOS Software xxxi

Understanding Command Modes xxxi

Getting Help xxxii

Example: How to Find Command Options xxxiii

Using the no and default Forms of Commands xxxv

Saving Configuration Changes xxxvi

Filtering Output from the show and more Commands xxxvi

Identifying Supported Platforms xxxvii

Using Feature Navigator xxxvii

Using Software Release Notes xxxvii

Cisco IOS Switching Services Overview XC-1

Document Organization XC-1

Related References XC-2

Contents

ivCisco IOS Switching Services Configuration Guide

CISCO IOS SWITCHING PATHS

Cisco IOS Switching Paths Overview XC-4

Basic Router Platform Architecture and Processes XC-4

Cisco Routing and Switching Processes XC-5

Routing Processes XC-5

Switching Processes XC-6

Basic Switching Paths XC-7

Process Switching XC-7

Fast Switching XC-7

CEF Switching XC-8

dCEF Switching XC-8

Platform and Switching Path Correlation XC-9

Features That Affect Performance XC-9

Queueing XC-10

Random Early Detection (RED) XC-10

Compression XC-10

Filtering XC-10

Encryption XC-10

Accounting XC-10

Configuring Fast Switching XC-11

Fast Switching Configuration Task List XC-11

Enabling AppleTalk Fast Switching XC-11

Enabling IP Fast Switching XC-12

Enabling Fast Switching on the Same IP Interface XC-12

Enabling Fast Switching of IPX Directed Broadcast Packets XC-13

Enabling SMDS Fast Switching XC-13

Disabling Fast Switching for Troubleshooting XC-13

Disabling AppleTalk Fast Switching XC-14

Disabling Banyan VINES Fast Switching XC-14

Disabling DECnet Fast Switching XC-14

Disabling IPX Fast Switching XC-15

Disabling ISO CLNS Fast Switching Through the Cache XC-15

Disabling XNS Fast Switching XC-15

Controlling the Route Cache XC-15

Controlling Route Cache Invalidation for IP XC-16

Displaying System and Network Statistics XC-16

Adjusting the Route Cache for IPX XC-16

Controlling IPX Route Cache Size XC-16

Contents

vCisco IOS Switching Services Configuration Guide

Controlling IPX Route Cache Invalidation XC-17

Padding Odd-Length IPX Packets XC-17

Cisco Express Forwarding Overview XC-19

Benefits XC-19

Restrictions XC-20

CEF Components XC-20

Forwarding Information Base XC-21

Adjacency Tables XC-21

Adjacency Discovery XC-21

Adjacency Resolution XC-21

Adjacency Types That Require Special Handling XC-21

Unresolved Adjacency XC-22

Supported Media XC-22

CEF Operation Modes XC-22

Central CEF Mode XC-23

Distributed CEF Mode XC-24

CEF and dCEF Additional Capabilities XC-25

TMS and CEF Nonrecursive Accounting XC-25

TMS Data XC-26

How Backbone Routers Collect TMS Data XC-26

Viewing the TMS Data XC-29

Viewing the TMS Data Through the NDA XC-29

Viewing the TMS Data by Reading the Virtual Files That Reside on the Backbone Router XC-30

Viewing TMS Data Through the show ip cef Command XC-32

Viewing the BGP Neighbor Autonomous Systems XC-32

Network Services Engine XC-33

Virtual Profile CEF XC-34

Configuring Cisco Express Forwarding XC-36

Configuring CEF XC-36

Enabling CEF or dCEF XC-37

Configuring Load Balancing for CEF XC-38

Configuring per-Destination Load Balancing XC-38

Configuring per-Packet Load Balancing XC-39

Selecting a Load Balancing Algorithm XC-39

Configuring Network Accounting for CEF XC-40

Enabling Network Accounting for CEF XC-40

Enabling a Backbone Router to Collect Traffic Matrix Statistics (TMS) Data XC-40

Using the NDA for TMS Data Collection XC-41

Contents

viCisco IOS Switching Services Configuration Guide

Verifying Network Accounting Information XC-43

Configuring Distributed Tunnel Switching for CEF XC-43

Configuring the Network Services Engine XC-44

Configuring the PXF Processor XC-44

Verifying the PXF Processor XC-44

Troubleshooting the PXF Processor XC-45

Monitoring the PXF Processor XC-45

Configuring Virtual Profile Switching for CEF XC-46

Verifying Virtual Profile Interfaces XC-46

Verifying CEF XC-46

Troubleshooting Tips XC-47

Enabling CEF Consistency Checkers XC-47

Displaying CEF Table Inconsistencies XC-47

Clearing CEF Table Inconsistencies XC-47

IP CEF Nonrecursive Accounting Example XC-48

NETFLOW SWITCHING

NetFlow Overview XC-50

Accounting Statistics XC-50

Capturing Traffic Data XC-50

NetFlow Cache XC-51

NetFlow Data Format XC-51

NetFlow Aggregation XC-54

Benefits XC-54

Aggregation Cache Schemes XC-54

Autonomous System Aggregation Scheme XC-56

Destination Prefix Aggregation Scheme XC-57

Prefix Aggregation Scheme XC-58

Protocol Port Aggregation Scheme XC-59

Source Prefix Aggregation Scheme XC-60

Aggregation Scheme Fields and Key Fields XC-61

Setting a NetFlow Minimum Mask XC-62

NetFlow Policy Routing XC-63

Benefits XC-63

Restrictions XC-64

Configuring NetFlow XC-65

What is NetFlow? XC-65

NetFlow Configuration Task List XC-66

Contents

viiCisco IOS Switching Services Configuration Guide

Enabling NetFlow XC-66

Exporting NetFlow Statistics XC-67

Customizing the Number of Entries in the NetFlow Cache XC-67

Managing NetFlow Statistics XC-68

Configuring IP Distributed and NetFlow on VIP Interfaces XC-68

Configuring an Aggregation Cache XC-69

Verifying Aggregation Cache Configuration and Data Export XC-69

Configuring a NetFlow Minimum Prefix Mask for Router-Based Aggregation XC-69

Configuring the Minimum Mask of a Prefix Aggregation Scheme XC-70

Configuring the Minimum Mask of a Destination-Prefix Aggregation Scheme XC-70

Configuring the Minimum Mask of a Source-Prefix Aggregation Scheme XC-70

Monitoring and Maintaining Minimum Masks for Aggregation Schemes XC-71

Configuring NetFlow Policy Routing XC-71

Monitoring NetFlow Policy Routing XC-72

NetFlow Configuration Examples XC-72

NetFlow Configuration Example XC-72

NetFlow Aggregation Configuration Examples XC-76

Autonomous System Configuration Example XC-76

Destination Prefix Configuration Example XC-76

Prefix Configuration Example XC-77

Protocol Port Configuration Example XC-77

Source Prefix Configuration Example XC-77

Setting a NetFlow Minimum Prefix Mask for Router-Based Aggregation Examples XC-77

Prefix Aggregation Scheme Example XC-77

Destination-Prefix Aggregation Scheme Example XC-78

Source-Prefix Aggregation Scheme Example XC-78

NetFlow Policy Routing Example XC-78

MULTIPROTOCOL LABEL SWITCHING

Multiprotocol Label Switching Overview XC-80

MPLS/Tag Switching Terminology XC-81

MPLS Commands and Saved Configurations XC-81

MPLS/Tag Switching CLI Command Summary XC-82

Benefits XC-83

Label Switching Functions XC-84

Distribution of Label Bindings XC-85

MPLS and Routing XC-85

MPLS Traffic Engineering XC-85

Contents

viiiCisco IOS Switching Services Configuration Guide

Why Use MPLS Traffic Engineering? XC-86

How MPLS Traffic Engineering Works XC-86

Mapping Traffic into Tunnels XC-87

Enhancement to the SPF Computation XC-87

Special Cases and Exceptions XC-88

Additional Enhancements to SPF Computation Using Configured Tunnel Metrics XC-89

Making the Transition from an IS-IS Network to a New Technology XC-90

New Extensions for the IS-IS Routing Protocol XC-91

The Problem in Theory XC-91

The Problem in Practice XC-91

First Solution for Making the Transition from an IS-IS Network to a New Technology XC-92

Second Solution for Making the Transition from an IS-IS Network to a New Technology XC-93

TLV Configuration Commands XC-93

Implementation in Cisco IOS Software XC-93

MPLS Virtual Private Networks XC-94

Benefits XC-94

Increased BGP Functionality XC-97

VPN Operation XC-98

Distribution of VPN Routing Information XC-99

BGP Distribution of VPN Routing Information XC-99

MPLS Forwarding XC-99

MPLS VPN Cable Interfaces XC-100

Benefits XC-102

Interautonomous Systems for MPLS VPNs XC-103

Routing Between Autonomous Systems XC-104

Routing Between Subautonomous Systems in a Confederation XC-109

HSRP Support for MPLS VPNS XC-110

MPLS Quality of Service XC-110

Specifying the QoS in the IP Precedence Field XC-111

MPLS Label Switch Controller XC-113

MPLS LSC Functional Description XC-113

Using Controlled ATM Switch Ports as Router Interfaces XC-115

Using the MPLS LSC as a Label Edge Device XC-115

Creating Virtual Trunks XC-116

Typical ATM Hybrid Network with Virtual Trunks XC-116

Virtual Trunk Configuration XC-117

Using LSC Redundancy XC-118

LSC Redundancy Architecture XC-119

General Redundancy Operational Modes XC-120

Contents

ixCisco IOS Switching Services Configuration Guide

How LSC Redundancy Differs from Router and Switch Redundancy XC-120

How the LSC, ATM Switch, and VSI Work Together XC-124

Implementing LSC Redundancy XC-124

Reducing the Number of LVCs for LSC Redundancy XC-128

Implementation Considerations XC-129

Reducing the Number of Label Switch Paths Created in an MPLS Network XC-130

Using an Access List to Disable Creation of LSPs to Destination IP Addresses XC-130

Disabling the LSC from Acting as an Edge LSR XC-133

Using the Cisco 6400 Universal Access Concentrator as an MPLS LSC XC-133

Cisco 6400 UAC Architectural Overview XC-134

Configuring Permanent Virtual Circuits and Permanent Virtual Paths XC-135

Control VC Setup for MPLS LSC Functions XC-137

Configuring the Cisco 6400 UAC to Perform Basic MPLS LSC Operations XC-138

Supporting ATM Forum Protocols XC-139

MPLS Egress NetFlow Accounting XC-139

Configuring Multiprotocol Label Switching XC-141

Configuring MPLS Levels of Control XC-141

Case 1—Enable MPLS Incrementally in a Network XC-143

Case 2—Route Labeled Packets to Network A Only XC-144

Case 3—Limit Label Distribution on an MPLS Network XC-144

Configuring a Router for MPLS Forwarding XC-145

Configuring MPLS Traffic Engineering XC-146

Configuring a Device to Support Tunnels XC-146

Configuring an Interface to Support RSVP-Based Tunnel Signalling and IGP Flooding XC-147

Configuring IS-IS for MPLS Traffic Engineering XC-147

Configuring OSPF for MPLS Traffic Engineering XC-148

Configuring an MPLS Traffic Engineering Tunnel XC-148

Configuring MPLS Traffic Engineering Paths XC-149

Configuring MPLS Virtual Private Networks XC-149

Defining VPNs XC-149

Configuring BGP Routing Sessions XC-150

Configuring PE to PE Routing Sessions XC-150

Configuring BGP PE to CE Routing Sessions XC-151

Configuring RIP PE to CE Routing Sessions XC-151

Configuring Static Route PE to CE Routing Sessions XC-152

Configuring MPLS VPNs with Cable Interfaces XC-152

Restrictions XC-153

Creating VRFs for Each VPN XC-154

Contents

xCisco IOS Switching Services Configuration Guide

Defining Subinterfaces on a Physical Cable Interface and Assigning VRFs XC-155

Configuring Cable Interface Bundles XC-156

Configuring Subinterfaces and MPLS VPNs on a Bundle Master XC-157

Configuring MPLS in the P Routers in the Provider Core XC-157

Verifying the MPLS VPN Configuration XC-158

Configuring Interautonomous Systems for MPLS VPNs XC-158

Configuring EBGP Routing for the Exchange of VPN Routes Between Autonomous Systems XC-159

Configuring EBGP Routing for the Exchange of VPN Routes Between Subautonomous Systems in a Confederation XC-159

Displaying VPN-IPv4 LFIB Entries XC-161

Verifying VPN Operation XC-161

Configuring MPLS QoS Backbone Support XC-162

LSRs XC-162

ATM-LSRs XC-162

ATM Switches XC-163

Configuring MPLS QoS XC-164

Configuring QoS XC-164

Setting the MPLS Experimental Field Value XC-165

Importance of Prioritizing a Packet Appropriately XC-165

Configuring the Ingress MPLS Router XC-166

Using the Modular QoS CLI to Configure the Ingress Label Switching Router XC-166

Configuring a Class Map to Classify IP Packets XC-166

Configuring a Policy Map to Set the MPLS Experimental Field XC-167

Configuring the Input Interface to Attach the Service Policy XC-167

Using CAR to Configure the Ingress Label Switching Router XC-167

Configuring a Rate Limit Access List for Classifying IP Packets XC-168

Configuring a Rate-Limit on an Input Interface to Set MPLS Packets XC-168

Configuring the Output IP QoS of the Packet XC-168

Configuring PVC Mode in a Non-MPLS-Enabled Core XC-169

Configuring Multi-VC Mode in a MPLS-Enabled Core XC-169

Configuring Multi-VCs Using the Cos-Map Function XC-170

Configuring DWFQ and Changing Queue Weights on an Outgoing Interface XC-170

Verifying QoS Operation XC-171

Configuring the MPLS Label Switch Controller XC-171

Configuring MPLS on the Cisco 7200 Series LSCs for BPX and IGX Switches XC-171

Configuring the Cisco 6400 UAC LSC XC-172

Configuring Cisco 6400 UAC NRP as an MPLS LSC XC-173

Configuring the Cisco 6400 UAC NSP for MPLS Connectivity to BPX XC-173

Verifying MPLS LSC Configuration XC-175

Contents

xiCisco IOS Switching Services Configuration Guide

Configuring MPLS Egress NetFlow Accounting XC-175

Enabling MPLS Egress NetFlow Accounting XC-176

Configuring NetFlow Aggregation Cache XC-176

Troubleshooting MPLS Egress NetFlow Accounting XC-176

Verifying MPLS Egress NetFlow Accounting Configuration XC-177

Monitoring and Maintaining MPLS Egress NetFlow Accounting XC-181

Verifying Configuration of MPLS Forwarding XC-181

MPLS Configuration Examples XC-182

Enabling MPLS Incrementally in a Network Example XC-182

Enabling MPLS for a Subset of Destination Prefixes Example XC-182

Selecting the Destination Prefixes and Paths Example XC-183

Displaying MPLS LDP Binding Information Example XC-183

Displaying MPLS Forwarding Table Information Example XC-184

Displaying MPLS Interface Information Example XC-185

Displaying MPLS LDP Neighbor Information Example XC-186

Enabling LSP Tunnel Signalling Example XC-186

Configuring an LSP Tunnel Example XC-186

Displaying the LSP Tunnel Information Example XC-187

Configuring MPLS Traffic Engineering Examples XC-187

Configuring MPLS Traffic Engineering Using IS-IS Example XC-188

Configuring MPLS Traffic Engineering Using OSPF Example XC-188

Configuring an MPLS Traffic Engineering Tunnel Example XC-189

Configuring Enhanced SPF Routing over a Tunnel Example XC-190

Configuring MPLS VPNs Examples XC-190

Configuring MPLS VPNs Example XC-190

Defining a Cable Subinterface Example XC-192

Cable Interface Bundling Example XC-192

Subinterface Definition on Bundle Master Example XC-193

Cable Interface Bundle Master Configuration Example XC-193

Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems XC-200

Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems in a Confederation XC-207

Implementing MPLS QoS Example XC-214

Configuring CEF Example XC-214

Running IP on Router 2 Example XC-215

Running IP on Router 1 Example XC-215

Running MPLS on Router 4 Example XC-215




Contents

xiiCisco IOS Switching Services Configuration Guide

Configuring ATM Switch 2 Example XC-220

Configuring ATM Switch 1 Example XC-220

Configuring an MPLS LSC Examples XC-221

Configuring ATM-LSRs Example XC-221

Configuring Multi-VCs Example XC-224

Configuring ATM-LSRs with a Cisco 6400 NRP Operating as LSC Example XC-226

Configuring ATM LSRs Through ATM Network Using Cisco 7200 LSCs Implementing Virtual Trunking Example XC-229

Configuring ATM LSRs Through ATM Network Using Cisco 6400 NRP LSCs Implementing Virtual Trunking Example XC-232

Configuring LSC Hot Redundancy Example XC-235

Configuring LSC Warm Standby Redundancy Example XC-240

Configuring an Interface Using Two VSI Partitions Example XC-241

Using an Access List to Control the Creation of Headend VCs XC-242

MPLS Egress NetFlow Accounting Example XC-244

MULTILAYER SWITCHING

Multilayer Switching Overview XC-247

Terminology XC-248

Introduction to MLS XC-248

Key MLS Features XC-249

MLS Implementation XC-250

Standard and Extended Access Lists XC-252

Restrictions on Using IP Router Commands with MLS Enabled XC-253

General Guidelines XC-253

Introduction to IP Multicast MLS XC-253

IP Multicast MLS Network Topology XC-253

IP Multicast MLS Components XC-255

Layer 2 Multicast Forwarding Table XC-255

Layer 3 Multicast MLS Cache XC-255

IP Multicast MLS Flow Mask XC-256

Layer 3-Switched Multicast Packet Rewrite XC-256

Partially and Completely Switched Flows XC-257

Introduction to IPX MLS XC-257

IPX MLS Components XC-258

IPX MLS Flows XC-258

MLS Cache XC-258

Flow Mask Modes XC-259

Layer 3-Switched Packet Rewrite XC-259

Contents

xiiiCisco IOS Switching Services Configuration Guide

IPX MLS Operation XC-260

Standard Access Lists XC-261

Guidelines for External Routers XC-262

Features That Affect MLS XC-262

Access Lists XC-262

Input Access Lists XC-262

Output Access Lists XC-262

Access List Impact on Flow Masks XC-263

Reflexive Access Lists XC-263

IP Accounting XC-263

Data Encryption XC-263

Policy Route Maps XC-263

TCP Intercept XC-263

Network Address Translation XC-263

Committed Access Rate XC-263

Maximum Transmission Unit XC-264

Configuring IP Multilayer Switching XC-265

Configuring and Monitoring MLS XC-265

Configuring MLS on a Router XC-266

Monitoring MLS XC-267

Monitoring MLS for an Interface XC-268

Monitoring MLS Interfaces for VTP Domains XC-268

Configuring NetFlow Data Export XC-269

Specifying an NDE Address on the Router XC-269

Multilayer Switching Configuration Examples XC-269

Router Configuration Without Access Lists Example XC-269

Router Configuration with a Standard Access List Example XC-270

Router Configuration with an Extended Access List Example XC-271

Configuring IP Multicast Multilayer Switching XC-273

Prerequisites XC-273

Restrictions XC-274

Router Configuration Restrictions XC-274

External Router Guidelines XC-275

Access List Restrictions and Guidelines XC-275

Configuring and Monitoring IP Multicast MLS XC-275

Enabling IP Multicast Routing XC-276

Enabling IP PIM XC-276

Enabling IP Multicast MLS XC-276

Contents

xivCisco IOS Switching Services Configuration Guide

Specifying a Management Interface XC-277

Monitoring and Maintaining IP Multicast MLS XC-277

IP Multicast MLS Configuration Examples XC-277

Basic IP Multicast MLS Network Examples XC-278

Network Topology Example XC-278

Operation Before IP Multicast MLS Example XC-279

Operation After IP Multicast MLS Example XC-279

Router Configuration XC-279

Switch Configuration XC-280

Complex IP Multicast MLS Network Examples XC-280

Network Topology Example XC-281

Operation Before IP Multicast MLS Example XC-282

Operation After IP Multicast MLS Example XC-282

Configuring IPX Multilayer Switching XC-285


Restrictions XC-286

General Configuration Guidelines XC-286

External Router Guidelines XC-286

Access List Restrictions XC-286

Restrictions on Interaction of IPX MLS with Other Features XC-287

Restriction on Maximum Transmission Unit Size XC-287

IPX MLS Configuration Task List XC-287

Adding an IPX MLS Interface to a VTP Domain XC-288

Enabling Multilayer Switching Protocol (MLSP) on the Router XC-288

Assigning a VLAN ID to a Router Interface XC-288

Enabling IPX MLS on a Router Interface XC-289

Specifying a Router Interface As a Management Interface XC-289

Verifying IPX MLS on the Router XC-289

Troubleshooting Tips XC-290

Monitoring and Maintaining IPX MLS on the Router XC-290

IPX MLS Configuration Examples XC-290

Complex IPX MLS Network Examples XC-291

IPX MLS Network Topology Example XC-291

Operation Before IPX MLS Example XC-292

Operation After IPX MLS Example XC-292

Switch A Configuration XC-293

Switch B Configuration XC-293

Switch C Configuration XC-294

Contents

xvCisco IOS Switching Services Configuration Guide

MLS-RP Configuration XC-294

Router with No Access Lists Configuration XC-295

Configuring a Router with a Standard Access List Example XC-295

MULTICAST DISTRIBUTED SWITCHING

Configuring Multicast Distributed Switching XC-298

MDS Configuration Task List XC-299

Enabling MDS XC-299

Monitoring and Maintaining MDS XC-299

MDS Configuration Example XC-300

VLANS

Routing Between VLANs Overview XC-302

What Is a VLAN? XC-302

LAN Segmentation XC-303

Security XC-304

Broadcast Control XC-304

Performance XC-304

Network Management XC-304

Network Monitoring Using SNMP XC-304

Communication Between VLANs XC-304

Relaying Function XC-305

Native VLAN XC-307

PVST+ XC-307

Ingress and Egress Rules XC-308

Integrated Routing and Bridging XC-308

VLAN Colors XC-309

Why Implement VLANs? XC-309

Communicating Between VLANs XC-309

Inter-Switch Link Protocol XC-310

IEEE 802.10 Protocol XC-310

IEEE 802.1Q Protocol XC-310

ATM LANE Protocol XC-310

ATM LANE Fast Simple Server Replication Protocol XC-311

VLAN Interoperability XC-311

Inter-VLAN Communications XC-311

VLAN Translation XC-312

Designing Switched VLANs XC-312

Contents

xviCisco IOS Switching Services Configuration Guide

Configuring Routing Between VLANs with Inter-Switch Link Encapsulation XC-313

Overview of the ISL Protocol XC-313

Frame Tagging in ISL XC-313

ISL Encapsulation Configuration Task List XC-314

Configuring AppleTalk Routing over ISL XC-314

Enabling AppleTalk Routing XC-315

Defining the VLAN Encapsulation Format XC-315

Configuring AppleTalk on the Subinterface XC-315

Configuring Banyan VINES Routing over ISL XC-316

Enabling Banyan VINES Routing XC-316


Configuring Banyan VINES on the Subinterface XC-316

Configuring DECnet Routing over ISL XC-316

Enabling DECnet Routing XC-317


Configuring DECnet on the Subinterface XC-317

Configuring the Hot Standby Router Protocol over ISL XC-317

Defining the Encapsulation Format XC-319

Defining the IP Address XC-319

Enabling HSRP XC-319

Configuring IP Routing over TRISL XC-320

Enabling IP Routing XC-320


Assigning IP Address to Network Interface XC-321

Configuring IPX Routing on 802.10 VLANs over ISL XC-321

Enabling NetWare Routing XC-322


Configuring NetWare on the Subinterface XC-322

Configuring IPX Routing over TRISL XC-322




Configuring VIP Distributed Switching over ISL XC-324


Enabling VIP Distributed Switching XC-325

Configuring ISL Encapsulation on the Subinterface XC-325

Configuring XNS Routing over ISL XC-325

Enabling XNS Routing XC-326


Configuring XNS on the Subinterface XC-326

Contents

xviiCisco IOS Switching Services Configuration Guide

Configuring CLNS Routing over ISL XC-326

Enabling CLNS Routing XC-327


Configuring CLNS on the Subinterface XC-327

Configuring IS-IS Routing over ISL XC-327

Enabling IS-IS Routing XC-328


Configuring IS-IS on the Subinterface XC-328

Monitoring and Maintaining VLAN Subinterfaces XC-328

ISL Encapsulation Configuration Examples XC-328

AppleTalk Routing over ISL Configuration Examples XC-329

Banyan VINES Routing over ISL Configuration Example XC-330

DECnet Routing over ISL Configuration Example XC-330

HSRP over ISL Configuration Example XC-330

IP Routing with RIF Between TrBRF VLANs Example XC-332

IP Routing Between a TRISL VLAN and an Ethernet ISL VLAN Example XC-333

IPX Routing over ISL Configuration Example XC-334

IPX Routing on FDDI Interfaces with SDE Example XC-335

Routing with RIF Between a TRISL VLAN and a Token Ring Interface Example XC-335

VIP Distributed Switching over ISL Configuration Example XC-336

XNS Routing over ISL Configuration Example XC-338

CLNS Routing over ISL Configuration Example XC-338

IS-IS Routing over ISL Configuration Example XC-338

Configuring Routing Between VLANs with IEEE 802.10 Encapsulation XC-339

Configuring AppleTalk Routing over IEEE 802.10 XC-339





Routing AppleTalk over IEEE 802.10 Configuration Example XC-341

Configuring Routing Between VLANs with IEEE 802.1Q Encapsulation XC-343

IEEE 802.1Q Encapsulation VLANs Configuration Task List XC-343

Configuring AppleTalk Routing over IEEE 802.1Q XC-344




Configuring IP Routing over IEEE 802.1Q XC-345


Contents

xviiiCisco IOS Switching Services Configuration Guide


Assigning an IP Address to Network Interface XC-346

Configuring IPX Routing over IEEE 802.1Q XC-346




Configuring a VLAN for a bridge-group with Default VLAN1 XC-347

Configuring a VLAN for a bridge-group as a Native VLAN XC-348


IEEE 802.1Q Encapsulation Configuration Examples XC-348

Configuring AppleTalk over IEEE 802.1Q Example XC-349

Configuring IP Routing over IEEE 802.1Q Example XC-349

Configuring IPX Routing over IEEE 802.1Q Example XC-349

VLAN 100 for Bridge Group 1 with Default VLAN 1 Example XC-349

VLAN 20 for Bridge Group 1 with Native VLAN Example XC-349

VLAN ISL or IEEE 802.1Q Routing Example XC-350

VLAN IEEE 802.1Q Bridging Example XC-351

VLAN IEEE 802.1Q IRB Example XC-352

LAN EMULATION

LAN Emulation Overview XC-354

LAN Emulation XC-354

LANE Components XC-355

LANE Operation and Communication XC-355

Client Joining an ELAN XC-356

Address Resolution XC-357

Multicast Traffic XC-357

Typical LANE Scenarios XC-358

Single ELAN Scenario XC-358

Multiple ELAN Scenario XC-359

Configuring LAN Emulation XC-360

LANE on ATM XC-360

Benefits of LANE XC-361

LANE Components XC-361

Simple Server Redundancy XC-361

LANE Implementation Considerations XC-362

Network Support XC-362

Hardware Support XC-363

Contents

xixCisco IOS Switching Services Configuration Guide

Addressing XC-363

LANE ATM Addresses XC-364

Method of Automatically Assigning ATM Addresses XC-364

Using ATM Address Templates XC-365

Rules for Assigning Components to Interfaces and Subinterfaces XC-366

LANE Configuration Task List XC-366

Creating a LANE Plan and Worksheet XC-367

Configuring the Prefix on the Switch XC-367

Setting Up the Signalling and ILMI PVCs XC-368

Displaying LANE Default Addresses XC-368

Entering the LECS’s ATM Address on the Cisco Switch XC-368

Entering the ATM Addresses on the Cisco LightStream 1010 ATM Switch XC-369

Entering the ATM Addresses on the Cisco LightStream 100 ATM Switch XC-369

Setting Up the LECS’s Database XC-370

Setting Up the Database for the Default ELAN Only XC-370

Setting Up the Database for Unrestricted-Membership Emulated LANs XC-371

Setting Up the Database for Restricted-Membership LANs XC-372

Enabling the LECS XC-373

Setting Up LESs and Clients XC-374

Setting Up the Server, BUS, and a Client on a Subinterface XC-375

Setting Up Only a Client on a Subinterface XC-375

Disabling the LE_FLUSH Process of LAN Emulation Clients XC-376

Setting Up LANE Clients for MPOA XC-377

Configuring Fault-Tolerant Operation XC-377

Simple Server Redundancy Requirements XC-377

Fast Simple Server Redundancy Requirements XC-378

Redundant Configuration Servers XC-378

Redundant Servers and BUSs XC-378

Implementation Considerations XC-378

SSRP Changes to Reduce Network Flap XC-380

Monitoring and Maintaining the LANE Components XC-381

LANE Configuration Examples XC-383

Default Configuration for a Single Ethernet ELAN Example XC-383

Default Configuration for a Single Ethernet ELAN with a Backup LECS and LES Example XC-384

Multiple Token Ring ELANs with Unrestricted Membership Example XC-385

Router 1 Configuration XC-386




Multiple Token Ring ELANs with Restricted Membership Example XC-388

Contents

xxCisco IOS Switching Services Configuration Guide





TR-LANE with 2-Port SRB Example XC-390



TR-LANE with Multiport SRB Example XC-392



Routing Between Token Ring and Ethernet Emulated LANs Example XC-394




Disabling LANE Flush Process Example XC-396

Configuring Token Ring LAN Emulation XC-397

Token Ring LANE on ATM XC-397

Benefits XC-398

LANE Token Ring Components XC-398

Network Support XC-399

Restrictions XC-400


Token Ring LANE Configuration Task List XC-402

Opening a Session from the Switch to the ATM Module XC-402

Creating a LANE Plan and Worksheet XC-403

Default LANE Configuration XC-404

Configuring the ATM Module from the Terminal XC-404

Configuring the ATM Module from NVRAM XC-405

Configuring the Prefix on the LightStream 1010 Switch XC-405

Setting Up the Signalling PVC XC-406

Displaying LANE Default Addresses XC-406

Entering the LECS ATM Address on the LightStream 1010 Switch XC-406

Configuring the LECS Database XC-407

Setting Up the Database for the Default ELAN XC-408

Setting Up the Database for Unrestricted-Membership ELANs XC-409

Setting Up the Database for Restricted-Membership ELANs XC-410

Binding the LECS to the ATM Interface XC-412

Setting Up a LES/BUS and a LEC XC-412

Setting Up the LES/BUS for an ELAN XC-413

Contents

xxiCisco IOS Switching Services Configuration Guide

Setting Up a LEC for an ELAN XC-413

Configuring Redundant LANE Services XC-416

Enabling Redundant LECSs XC-417

Enabling ILMI Keepalive Timeout XC-417

Using UNI 3.1 Signalling Support XC-418

Configuring Fast SSRP for Redundant LANE Services XC-418

Verifying the LANE Setup XC-420

Monitoring and Maintaining LANE Components XC-421

Token Ring LANE Configuration Example XC-421

Example Assumptions XC-422

Configuring the TrCRF Example XC-422

Configuring the LES/BUS and the LEC Example XC-422

Multiprotocol over ATM Overview XC-427

How MPOA Works XC-427

Traffic Flow XC-429

Interaction with LANE XC-429

MPOA Components XC-430

Benefits XC-431

Configuring an MPC/MPS XC-431

Configuring the Multiprotocol over ATM Client XC-433

How MPC Works XC-433

MPC Configuration Task List XC-433

Configuring the ELAN ID XC-434

Configuring the MPC XC-434

Configuring the MPC Variables XC-435

Monitoring and Maintaining the MPC XC-435

MPC Configuration Example XC-436

Configuring the Multiprotocol over ATM Server XC-439

How MPS Works XC-439

MPS-NHRP-Routing Interaction XC-439

Shortcut Domains XC-440

MPS Configuration Task List XC-440

Configuring the ELAN ID XC-440

Configuring the MPS XC-441

Configuring the MPS Variables XC-441

Monitoring and Maintaining the MPS XC-442

MPS Configuration Example XC-442

Contents

xxiiCisco IOS Switching Services Configuration Guide

Configuring Token Ring LAN Emulation for Multiprotocol over ATM XC-445

How Token Ring MPOA Works XC-445

Token Ring LANE for MPOA Configuration Task List XC-445

Configuring a Token Ring LEC XC-446

Configuring the LECS Database XC-446

Configuring the LES/BUS XC-446

Token Ring LANE Configuration Examples XC-447

MPOA Token Ring LANE Configuration in an IP-Routed Domain Example XC-447

MPOA Token Ring LANE Configuration in an IP SRB-Routed Domain Example XC-451

INDEX

xxiiiCisco IOS Switching Services Configuration Guide

About Cisco IOS Software Documentation

This chapter discusses the objectives, audience, organization, and conventions of Cisco IOS software documentation. It also provides sources for obtaining documentation from Cisco Systems.

Documentation ObjectivesCisco IOS software documentation describes the tasks and commands necessary to configure and maintain Cisco networking devices.

AudienceThe Cisco IOS software documentation set is intended primarily for users who configure and maintain Cisco networking devices (such as routers and switches) but who may not be familiar with the tasks, the relationship between tasks, or the Cisco IOS software commands necessary to perform particular tasks.

Documentation OrganizationThe Cisco IOS software documentation set consists of documentation modules and master indexes. In addition to the main documentation set, there are supporting documents and resources.

Documentation ModulesThe Cisco IOS documentation modules consist of configuration guides and corresponding command reference publications. Chapters in a configuration guide describe protocols, configuration tasks, and Cisco IOS software functionality and contain comprehensive configuration examples. Chapters in a command reference publication provide complete Cisco IOS command syntax information. Use each configuration guide in conjunction with its corresponding command reference publication.

About Cisco IOS Software DocumentationDocumentation Organization

xxivCisco IOS Switching Services Configuration Guide

Figure 1 shows the Cisco IOS software documentation modules.

Note The abbreviations (for example, FC and FR) next to the book icons are page designators, which are defined in a key in the index of each document to help you with navigation. The bullets under each module list the major technology areas discussed in the corresponding books.

Figure 1 Cisco IOS Software Documentation Modules

Cisco IOSIP ConfigurationGuide

IPC

Cisco IOSConfigurationFundamentalsConfigurationGuide

Cisco IOSConfigurationFundamentalsCommandReference

Module FC/FR:• Cisco IOS User

Interfaces• File Management • System Management

Cisco IOSIP CommandReference,Volume 2 of 3:RoutingProtocols

Module IPC/IP1R/IP2R/IP3R:• IP Addressing and Services• IP Routing Protocols• IP Multicast

Cisco IOSAppleTalk andNovell IPXConfigurationGuide

Cisco IOSAppleTalk andNovell IPXCommandReference

Module P2C/P2R:• AppleTalk• Novell IPX

Cisco IOSApollo Domain,Banyan VINES,DECnet, ISOCLNS, and XNSConfigurationGuide

Cisco IOSApollo Domain,Banyan VINES,DECnet, ISOCLNS, and XNSCommandReference

Module P3C/P3R:• Apollo Domain• Banyan VINES• DECnet• ISO CLNS• XNS

Cisco IOSWide-AreaNetworkingConfigurationGuide

Cisco IOSWide-AreaNetworkingCommandReference

Module WC/WR:• ATM• Broadband Access• Frame Relay• SMDS• X.25 and LAPB

Cisco IOSSecurityConfigurationGuide

Cisco IOSSecurityCommandReference

Module SC/SR:• AAA Security Services• Security Server Protocols• Traffic Filtering and Firewalls• IP Security and Encryption• Passwords and Privileges• Neighbor Router Authentication• IP Security Options• Supported AV Pairs

Cisco IOSInterfaceConfigurationGuide

Cisco IOSInterfaceCommandReference

Module IC/IR:• LAN Interfaces• Serial Interfaces• Logical Interfaces

47953

FC

FR

IP2R

WC

WR

SC

SR

MWC

MWR

Cisco IOSMobileWirelessConfigurationGuide

Cisco IOSMobileWirelessCommandReference

Module MWC/MWR:• General Packet

Radio Service

IC

IR

Cisco IOSIP CommandReference,Volume 1 of 3:Addressingand Services

Cisco IOSIP CommandReference,Volume 3 of 3:Multicast

P2C

P2R

IP1R

IP3R

P3C

P3R

About Cisco IOS Software DocumentationDocumentation Organization

xxvCisco IOS Switching Services Configuration Guide

Cisco IOSVoice, Video,and FaxConfigurationGuide

Cisco IOSVoice, Video,and FaxCommandReference

Module VC/VR:• Voice over IP• Call Control Signalling• Voice over

Frame Relay• Voice over ATM• Telephony Applications• Trunk Management• Fax, Video, and

Modem Support

Cisco IOSQuality ofServiceSolutionsConfigurationGuide

Cisco IOSQuality ofServiceSolutionsCommandReference

Module QC/QR:• Packet Classification• Congestion Management• Congestion Avoidance• Policing and Shaping• Signalling• Link Efficiency

Mechanisms

Module DC/DR:• Preparing for Dial Access• Modem and Dial Shelf Configuration

and Management• ISDN Configuration• Signalling Configuration• Dial-on-Demand Routing

Configuration• Dial-Backup Configuration• Dial-Related Addressing Services• Virtual Templates, Profiles, and

Networks• PPP Configuration• Callback and Bandwidth Allocation

Configuration• Dial Access Specialized Features• Dial Access Scenarios

Module BC/B1R:• Transparent

Bridging• SRB• Token Ring

Inter-Switch Link• Token Ring Route

Switch Module• RSRB• DLSw+• Serial Tunnel and

Block Serial Tunnel• LLC2 and SDLC• IBM Network

Media Translation• SNA Frame Relay

Access• NCIA Client/Server• Airline Product Set

Module BC/B2R:• DSPU and SNA

Service Point• SNA Switching

Services• Cisco Transaction

Connection• Cisco Mainframe

Channel Connection• CLAW and TCP/IP

Offload• CSNA, CMPC,

and CMPC+• TN3270 Server

Cisco IOSSwitchingServicesConfigurationGuide

Cisco IOSSwitchingServicesCommandReference

Module XC/XR:• Cisco IOS

Switching Paths• NetFlow Switching• Multiprotocol Label Switching• Multilayer Switching• Multicast Distributed Switching• Virtual LANs• LAN Emulation

47954

Cisco IOSBridging andIBM NetworkingConfigurationGuide

Cisco IOSBridgingand IBMNetworkingCommandReference,Volume 1 of 2

Cisco IOSBridgingand IBMNetworkingCommandReference,Volume 2 of 2

XC

DC

DR

TC

TR

BC

XR

B1R B2R

QC

QR

VC

VR

Cisco IOSTerminalServicesConfigurationGuide

Cisco IOSTerminalServicesCommandReference

Module TC/TR:• ARA• LAT• NASI• Telnet• TN3270• XRemote• X.28 PAD• Protocol Translation

Cisco IOSDialTechnologiesConfigurationGuide

Cisco IOSDialTechnologiesCommandReference

About Cisco IOS Software DocumentationNew and Changed Information

xxviCisco IOS Switching Services Configuration Guide

Master IndexesTwo master indexes provide indexing information for the Cisco IOS software documentation set: an index for the configuration guides and an index for the command references. Individual books also contain a book-specific index.

The master indexes provide a quick way for you to find a command when you know the command name but not which module contains the command. When you use the online master indexes, you can click the page number for an index entry and go to that page in the online document.

Supporting Documents and ResourcesThe following documents and resources support the Cisco IOS software documentation set:

• Cisco IOS Command Summary (two volumes)—This publication explains the function and syntax of the Cisco IOS software commands. For more information about defaults and usage guidelines, refer to the Cisco IOS command reference publications.

• Cisco IOS System Error Messages—This publication lists and describes Cisco IOS system error messages. Not all system error messages indicate problems with your system. Some are purely informational, and others may help diagnose problems with communications lines, internal hardware, or the system software.

• Cisco IOS Debug Command Reference—This publication contains an alphabetical listing of the debug commands and their descriptions. Documentation for each command includes a brief description of its use, command syntax, usage guidelines, and sample output.

• Internetworking Terms and Acronyms—This Cisco publication compiles and defines the terms and acronyms used in the internetworking industry.

• New feature documentation—Feature module documentation introduces new networking functionality, released after the publication of the Cisco IOS software documentation set, that supports Cisco networking technology and hardware.

• Release notes—This documentation describes system requirements, provides new and changed information, and includes other useful information about specific software releases.

• Caveats documentation—This documentation provides information about Cisco IOS software defects in specific software releases.

New and Changed InformationSince the last release of the Cisco IOS Switching Services Configuration Guide, the term ‘quality of service’ (QoS) replaces the term ‘class of service’ (CoS). All references to Multiprotocol Label Switching (MPLS) CoS functionality has been replaced by the MPLS QoS functionality, which is documented in the “Multiprotocol Label Switching Overview” chapter and the “Configuring Multiprotocol Label Switching” chapter.

About Cisco IOS Software DocumentationDocument Conventions

xxviiCisco IOS Switching Services Configuration Guide

Document ConventionsThe Cisco IOS documentation set uses the following conventions:

Examples use the following conventions:

The following conventions are used to attract the attention of the reader:

Caution Means reader be careful. In this situation, you might do something that could result in equipment damage or loss of data.

Note Means reader take note. Notes contain helpful suggestions or references to materials not contained in this manual.

Timesaver Means the described action saves time. You can save time by performing the action described in the paragraph.

Within Cisco IOS software documentation, the term router is generally used to refer to a variety of Cisco products (for example, routers, access servers, and switches). Routers, access servers, and other networking devices that support Cisco IOS software are shown interchangeably within examples. These products are used only for illustrative purposes; that is, an example that shows one product does not necessarily indicate that other products are not supported.

Convention Description

^ or Ctrl The ^ and Ctrl symbols represent the Control key. For example, the key combination ^D or Ctrl-D means hold down the Control key while you press the D key. Keys are indicated in capital letters but are not case sensitive.

string A string is a nonquoted set of characters. For example, when setting an SNMP community string to public, do not use quotation marks around the string or the string will include the quotation marks.


screen Examples of information displayed on the screen are set in Courier font.

boldface screen Examples of text that you must enter are set in Courier bold font.

< > Angle brackets enclose nonprinting characters, such as passwords.

! An exclamation point at the beginning of a line indicates a comment line. (Exclamation points are also displayed by the Cisco IOS software for certain processes.)

[ ] Square brackets enclose default responses to system prompts.

About Cisco IOS Software DocumentationCommand Syntax Conventions

xxviiiCisco IOS Switching Services Configuration Guide

Command Syntax ConventionsCommand syntax descriptions use the following conventions:

Cisco.comCisco.com is the foundation of a suite of interactive, networked services that provides immediate, open access to Cisco information and resources at any time, from anywhere in the world. This highly integrated Internet application is a powerful, easy-to-use tool for doing business with Cisco.

Cisco.com provides a broad range of features and services to help customers and partners streamline business processes and improve productivity. Through Cisco.com, you can find information about Cisco and our networking solutions, services, and programs. In addition, you can resolve technical issues using online technical support, you can download and test software packages, and you can order Cisco learning materials and merchandise. Valuable online skill assessment, training, and certification programs are also available.

Customers and partners can self-register on Cisco.com to obtain additional personalized information and services. Registered users can order products, check on the status of an order, access technical support, and view benefits specific to their relationships with Cisco.

To access Cisco.com, go to the following website:

http://www.cisco.com

World Wide WebYou can access the most current Cisco documentation on the World Wide Web at the following sites:

• http://www.cisco.com

• http://www-china.cisco.com

• http://www-europe.cisco.com


boldface Boldface text indicates commands and keywords that you enter literally as shown.

italics Italic text indicates arguments for which you supply values.

[x] Square brackets enclose an optional element (keyword or argument).

{x} Braces enclose a required element (keyword or argument).

| A vertical line, or pipe, indicates a choice within an optional or required element.

[x {y | z}] Braces and vertical lines (pipes) within square brackets indicate a required choice within an optional element.

About Cisco IOS Software DocumentationDocumentation CD-ROM

xxixCisco IOS Switching Services Configuration Guide

Documentation CD-ROMCisco documentation and additional literature are available in a CD-ROM package, which ships with your product. The Documentation CD-ROM is updated monthly and may be more current than printed documentation. The CD-ROM package is available as a single unit or as an annual subscription.

Ordering DocumentationCisco documentation can by ordered in the following ways:

• Registered Cisco Direct Customers can order Cisco product documentation from the Networking Products MarketPlace:

http://www.cisco.com/cgi-bin/order/order_root.pl

• Registered Cisco.com users can order the Documentation CD-ROM through the online Subscription Store:

http://www.cisco.com/go/subscription

• Nonregistered Cisco.com users can order documentation through a local account representative by calling Cisco corporate headquarters (California, USA) at 408 526-7208 or, in North America, by calling 800 553-NETS(6387).

Documentation FeedbackIf you are reading Cisco product documentation on the World Wide Web, you can submit technical comments electronically. Click Feedback in the toolbar and select Documentation. After you complete the form, click Submit to send it to Cisco.

You can e-mail your comments to [email protected].

To submit your comments by mail, for your convenience many documents contain a response card behind the front cover. Otherwise, you can mail your comments to the following address:

Cisco Systems, Inc.Document Resource Connection170 West Tasman DriveSan Jose, CA 95134-9883

We appreciate your comments.

About Cisco IOS Software DocumentationDocumentation Feedback

xxxCisco IOS Switching Services Configuration Guide

xxxiCisco IOS Switching Services Configuration Guide

Using Cisco IOS Software

This chapter provides helpful tips for understanding and configuring Cisco IOS software using the command-line interface (CLI). It contains the following sections:

• Understanding Command Modes

• Getting Help

• Using the no and default Forms of Commands

• Saving Configuration Changes

• Filtering Output from the show and more Commands

• Identifying Supported Platforms

For an overview of Cisco IOS software configuration, refer to the Cisco IOS Configuration Fundamentals Configuration Guide.

For information on the conventions used in the Cisco IOS software documentation set, see the chapter “About Cisco IOS Software Documentation” located at the beginning of this book.

Understanding Command ModesYou use the CLI to access Cisco IOS software. Because the CLI is divided into many different modes, the commands available to you at any given time depend on the mode you are currently in. Entering a question mark (?) at the CLI prompt allows you to obtain a list of commands available for each command mode.

When you log in to the CLI, you are in user EXEC mode. User EXEC mode contains only a limited subset of commands. To have access to all commands, you must enter privileged EXEC mode, normally by using a password. From privileged EXEC mode you can issue any EXEC command—user or privileged mode—or you can enter global configuration mode. Most EXEC commands are one-time commands. For example, show commands show important status information, and clear commands clear counters or interfaces. The EXEC commands are not saved when the software reboots.

Configuration modes allow you to make changes to the running configuration. If you later save the running configuration to the startup configuration, these changed commands are stored when the software is rebooted. To enter specific configuration modes, you must start at global configuration mode. From global configuration mode, you can enter interface configuration mode and a variety of other modes, such as protocol-specific modes.

ROM monitor mode is a separate mode used when the Cisco IOS software cannot load properly. If a valid software image is not found when the software boots or if the configuration file is corrupted at startup, the software might enter ROM monitor mode.

Using Cisco IOS SoftwareGetting Help

xxxiiCisco IOS Switching Services Configuration Guide

Table 1 describes how to access and exit various common command modes of the Cisco IOS software. It also shows examples of the prompts displayed for each mode.

For more information on command modes, refer to the “Using the Command-Line Interface” chapter in the Cisco IOS Configuration Fundamentals Configuration Guide.

Getting HelpEntering a question mark (?) at the CLI prompt displays a list of commands available for each command mode. You can also get a list of keywords and arguments associated with any command by using the context-sensitive help feature.

To get help specific to a command mode, a command, a keyword, or an argument, use one of the following commands:

Table 1 Accessing and Exiting Command Modes

Command Mode Access Method Prompt Exit Method

User EXEC Log in. Router> Use the logout command.

Privileged EXEC

From user EXEC mode, use the enable EXEC command.

Router# To return to user EXEC mode, use the disable command.

Global configuration

From privileged EXEC mode, use the configure terminal privileged EXEC command.

Router(config)# To return to privileged EXEC mode from global configuration mode, use the exit or end command, or press Ctrl-Z.

Interface configuration

From global configuration mode, specify an interface using an interface command.

Router(config-if)# To return to global configuration mode, use the exit command.

To return to privileged EXEC mode, use the end command, or press Ctrl-Z.

ROM monitor From privileged EXEC mode, use the reload EXEC command. Press the Break key during the first 60 seconds while the system is booting.

> To exit ROM monitor mode, use the continue command.

Command Purposehelp Provides a brief description of the help system in any command mode.

abbreviated-command-entry? Provides a list of commands that begin with a particular character string. (No space between command and question mark.)

abbreviated-command-entry<Tab> Completes a partial command name.

? Lists all commands available for a particular command mode.

command ? Lists the keywords or arguments that you must enter next on the command line. (Space between command and question mark.)


xxxiiiCisco IOS Switching Services Configuration Guide

Example: How to Find Command OptionsThis section provides an example of how to display syntax for a command. The syntax can consist of optional or required keywords and arguments. To display keywords and arguments for a command, enter a question mark (?) at the configuration prompt or after entering part of a command followed by a space. The Cisco IOS software displays a list and brief description of available keywords and arguments. For example, if you were in global configuration mode and wanted to see all the keywords or arguments for the arap command, you would type arap ?.

The <cr> symbol in command help output stands for “carriage return.” On older keyboards, the carriage return key is the Return key. On most modern keyboards, the carriage return key is the Enter key. The <cr> symbol at the end of command help output indicates that you have the option to press Enter to complete the command and that the arguments and keywords in the list preceding the <cr> symbol are optional. The <cr> symbol by itself indicates that no more arguments or keywords are available and that you must press Enter to complete the command.

Table 2 shows examples of how you can use the question mark (?) to assist you in entering commands. The table steps you through configuring an IP address on a serial interface on a Cisco 7206 router that is running Cisco IOS Release 12.0(3).

Table 2 How to Find Command Options

Command CommentRouter> enablePassword: <password>Router#

Enter the enable command and password to access privileged EXEC commands. You are in privileged EXEC mode when the prompt changes to Router#.

Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)#

Enter the configure terminal privileged EXEC command to enter global configuration mode. You are in global configuration mode when the prompt changes to Router(config)#.

Router(config)# interface serial ?<0-6> Serial interface number

Router(config)# interface serial 4 ?/

Router(config)# interface serial 4/ ?<0-3> Serial interface number

Router(config)# interface serial 4/0Router(config-if)#

Enter interface configuration mode by specifying the serial interface that you want to configure using the interface serial global configuration command.

Enter ? to display what you must enter next on the command line. In this example, you must enter the serial interface slot number and port number, separated by a forward slash.

You are in interface configuration mode when the prompt changes to Router(config-if)#.


xxxivCisco IOS Switching Services Configuration Guide

Router(config-if)# ?Interface configuration commands:

.

.

.ip Interface Internet Protocol config commandskeepalive Enable keepalivelan-name LAN Name commandllc2 LLC2 Interface Subcommandsload-interval Specify interval for load calculation for an

interfacelocaddr-priority Assign a priority grouplogging Configure logging for interfaceloopback Configure internal loopback on an interfacemac-address Manually set interface MAC addressmls mls router sub/interface commandsmpoa MPOA interface configuration commandsmtu Set the interface Maximum Transmission Unit (MTU)netbios Use a defined NETBIOS access list or enable

name-cachingno Negate a command or set its defaultsnrzi-encoding Enable use of NRZI encodingntp Configure NTP...

Router(config-if)#

Enter ? to display a list of all the interface configuration commands available for the serial interface. This example shows only some of the available interface configuration commands.

Router(config-if)# ip ?Interface IP configuration subcommands:

access-group Specify access control for packetsaccounting Enable IP accounting on this interfaceaddress Set the IP address of an interfaceauthentication authentication subcommandsbandwidth-percent Set EIGRP bandwidth limitbroadcast-address Set the broadcast address of an interfacecgmp Enable/disable CGMPdirected-broadcast Enable forwarding of directed broadcastsdvmrp DVMRP interface commandshello-interval Configures IP-EIGRP hello intervalhelper-address Specify a destination address for UDP broadcastshold-time Configures IP-EIGRP hold time...

Router(config-if)# ip

Enter the command that you want to configure for the interface. This example uses the ip command.

Enter ? to display what you must enter next on the command line. This example shows only some of the available interface IP configuration commands.

Table 2 How to Find Command Options (continued)

Command Comment

Using Cisco IOS SoftwareUsing the no and default Forms of Commands

xxxvCisco IOS Switching Services Configuration Guide

Using the no and default Forms of CommandsAlmost every configuration command has a no form. In general, use the no form to disable a function. Use the command without the no keyword to reenable a disabled function or to enable a function that is disabled by default. For example, IP routing is enabled by default. To disable IP routing, use the no ip routing command; to reenable IP routing, use the ip routing command. The Cisco IOS software command reference publications provide the complete syntax for the configuration commands and describe what the no form of a command does.

Configuration commands also can have a default form, which returns the command settings to the default values. Most commands are disabled by default, so in such cases using the default form has the same result as using the no form of the command. However, some commands are enabled by default and

Router(config-if)# ip address ?A.B.C.D IP addressnegotiated IP Address negotiated over PPP

Router(config-if)# ip address

Enter the command that you want to configure for the interface. This example uses the ip address command.

Enter ? to display what you must enter next on the command line. In this example, you must enter an IP address or the negotiated keyword.

A carriage return (<cr>) is not displayed; therefore, you must enter additional keywords or arguments to complete the command.

Router(config-if)# ip address 172.16.0.1 ?A.B.C.D IP subnet mask

Router(config-if)# ip address 172.16.0.1

Enter the keyword or argument you want to use. This example uses the 172.16.0.1 IP address.

Enter ? to display what you must enter next on the command line. In this example, you must enter an IP subnet mask.

A <cr> is not displayed; therefore, you must enter additional keywords or arguments to complete the command.

Router(config-if)# ip address 172.16.0.1 255.255.255.0 ?secondary Make this IP address a secondary address<cr>

Router(config-if)# ip address 172.16.0.1 255.255.255.0

Enter the IP subnet mask. This example uses the 255.255.255.0 IP subnet mask.

Enter ? to display what you must enter next on the command line. In this example, you can enter the secondary keyword, or you can press Enter.

A <cr> is displayed; you can press Enter to complete the command, or you can enter another keyword.

Router(config-if)# ip address 172.16.0.1 255.255.255.0Router(config-if)#

In this example, Enter is pressed to complete the command.

Table 2 How to Find Command Options (continued)

Command Comment

Using Cisco IOS SoftwareSaving Configuration Changes

xxxviCisco IOS Switching Services Configuration Guide

have variables set to certain default values. In these cases, the default form of the command enables the command and sets the variables to their default values. The Cisco IOS software command reference publications describe the effect of the default form of a command if the command functions differently than the no form.

Saving Configuration ChangesUse the copy system:running-config nvram:startup-config command to save your configuration changes to the startup configuration so that the changes will not be lost if the software reloads or a power outage occurs. For example:

Router# copy system:running-config nvram:startup-configBuilding configuration...

It might take a minute or two to save the configuration. After the configuration has been saved, the following output appears:

[OK]Router#

On most platforms, this task saves the configuration to NVRAM. On the Class A Flash file system platforms, this task saves the configuration to the location specified by the CONFIG_FILE environment variable. The CONFIG_FILE variable defaults to NVRAM.

Filtering Output from the show and more CommandsIn Cisco IOS Release 12.0(1)T and later releases, you can search and filter the output of show and more commands. This functionality is useful if you need to sort through large amounts of output or if you want to exclude output that you need not see.

To use this functionality, enter a show or more command followed by the “pipe” character (|); one of the keywords begin, include, or exclude; and a regular expression on which you want to search or filter (the expression is case-sensitive):

command | {begin | include | exclude} regular-expression

The output matches certain lines of information in the configuration file. The following example illustrates how to use output modifiers with the show interface command when you want the output to include only lines in which the expression “protocol” appears:

Router# show interface | include protocol

FastEthernet0/0 is up, line protocol is upSerial4/0 is up, line protocol is upSerial4/1 is up, line protocol is upSerial4/2 is administratively down, line protocol is downSerial4/3 is administratively down, line protocol is down

For more information on the search and filter functionality, refer to the “Using the Command-Line Interface” chapter in the Cisco IOS Configuration Fundamentals Configuration Guide.

Using Cisco IOS SoftwareIdentifying Supported Platforms

xxxviiCisco IOS Switching Services Configuration Guide

Identifying Supported PlatformsCisco IOS software is packaged in feature sets consisting of software images that support specific platforms. The feature sets available for a specific platform depend on which Cisco IOS software images are included in a release. To identify the set of software images available in a specific release or to find out if a feature is available in a given Cisco IOS software image, see the following sections:

• Using Feature Navigator

• Using Software Release Notes

Using Feature NavigatorFeature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a particular set of features and which features are supported in a particular Cisco IOS image.

Feature Navigator is available 24 hours a day, 7 days a week. To access Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, e-mail the Contact Database Administration group at [email protected]. If you do not have an account on Cisco.com, go to http://www.cisco.com/register and follow the directions to establish an account.

To use Feature Navigator, you must have a JavaScript-enabled web browser such as Netscape 3.0 or later, or Internet Explorer 4.0 or later. Internet Explorer 4.0 always has JavaScript enabled. To enable JavaScript for Netscape 3.x or Netscape 4.x, follow the instructions provided with the web browser. For JavaScript support and enabling instructions for other browsers, check with the browser vendor.

Feature Navigator is updated when major Cisco IOS software releases and technology releases occur. You can access Feature Navigator at the following URL:

http://www.cisco.com/go/fn

Using Software Release NotesCisco IOS software releases include release notes that provide the following information:

• Platform support information

• Memory recommendations

• Microcode support information

• Feature set tables

• Feature descriptions

• Open and resolved severity 1 and 2 caveats for all platforms

Release notes are intended to be release-specific for the most current release, and the information provided in these documents may not be cumulative in providing information about features that first appeared in previous releases.

Using Cisco IOS SoftwareIdentifying Supported Platforms

xxxviiiCisco IOS Switching Services Configuration Guide

XC-1Cisco IOS Switching Services Configuration Guide

Cisco IOS Switching Services Overview

The Cisco IOS Switching Services Configuration Guide provides guidelines for configuring switching paths and routing between virtual local-area networks (VLANs) by using Cisco IOS software.

This guide is intended for the network administrator who designs and implements router-based internetworks and needs to incorporate switching, NetFlow accounting, or routing between VLANs into the network. It presents a set of general guidelines for configuring switching of various protocols, NetFlow accounting, routing between VLANs, and LAN emulation. The objective of this guide is to provide you with the information you need to configure any of these features.

You should know how to configure a Cisco router and should be familiar with the protocols and media that your routers are configured to support. Knowledge of basic network topology is essential.

Document Organization This document comprises seven parts, each focusing on a different aspect of switching within Cisco IOS software. Each part begins with a brief technology overview and follows with the corresponding configuration guidelines for that technology or set of features. This document contains these parts:

• Cisco IOS Switching Paths—Provides an overview of basic routing and switching processes. It describes switching paths available in Cisco IOS software. Configuration guidelines are provided for configuring and managing fast switching of various protocols. Provides an overview of Cisco Express Forwarding (CEF), the advanced Layer 3 IP switching technology that optimizes performance and scalability in networks with large and dynamic traffic patterns. Guidelines are provided for configuring and managing CEF.

• NetFlow Switching—Provides an overview of the NetFlow switching technology and describes the NetFlow accounting features. Guidelines are provided for configuring and managing NetFlow switching.

• Multiprotocol Label Switching (MPLS)—Provides an overview of MPLS Switching, the switching technology that combines the performance of Layer 2 switching with the scalability of Layer 3 routing. Guidelines are provided for configuring and managing MPLS Switching.

• Multilayer Switching—Provides an overview of Multilayer Switching (MLS). MLS provides high-performance Layer 3 switching for the Catalyst 5000 series LAN switches working in conjunction with Cisco routers. Guidelines are provided for configuring and managing IP MLS, IP Multicast MLS, and IPX MLS on Cisco routers.

• Multicast Distributed Switching—Provides an overview of Multicast Distributed Switching (MDS). MDS performs distributed switching of multicast packets in the line cards of Route Switch Processor (RSP)-based platforms. Guidelines are provided for configuring and managing MDS.

Cisco IOS Switching Services OverviewRelated References


• VLANs—Provides an overview of VLANs. Guidelines are provided for configuring routing between VLANs using the Inter-Switch Link (ISL), IEEE 802.10, and IEEE 802.1Q protocols for packet encapsulation.

• LAN Emulation—Provides an overview of LAN Emulation (LANE). Guidelines are provided for defining VLANs in ATM networks and Multiprotocol over ATM (MPOA).

Related ReferencesThe references listed in this section contain background information that is helpful in designing internetworks that incorporate switching and VLANs when planning routing between VLANs:

• Cisco Internetwork Design Guide

This guide presents a set of general guidelines for planning internetworks and provides specific suggestions for several key internetworking implementations. This guide focuses on design issues of large-scale implementations for environments such as IP internetworks, Enhanced Interior Gateway Routing Protocol (IGRP), Open Shortest Path First (OSPF), IBM System Network Architecture (SNA) internetworks, source-route bridging (SRB), Synchronous Data Link Control (SDLC) and serial tunneling (STUN), SDLC Logical Link, Control type 2 (SDLLC), Qualified Logical Link Control (QLLC), ATM internetworks, packet service internetworks, Frame Relay, and dial-on-demand routing (DDR) internetworks.

• Cisco Catalyst 5000 Series Software Configuration Guide

This guide is designed to help you understand the Catalyst 5000 series switches, initially configure the switch to work in your network, and customize the switch configuration to fit your needs. For an alphabetical listing of software commands used to configure and maintain the switch, refer to the Catalyst 5000 Series Command Reference publication.

• CiscoWorks for Switched Internetworks—VlanDirector Getting Started Guide

This guide provides an overview of VLANs and describes how to use VlanDirector to create and manage VLANs. VlanDirector is a management tool with a graphical user interface that provides multiple windows for adding new users, moving users between wiring closets, changing user VLAN associations, displaying configuration status, and providing both physical and logical views of interconnected Catalyst switches. Network administrators responsible for initial setup and configuration of VLANs will find this guide useful for understanding VLANs and segmenting LANs with VLAN configurations.

Cisco IOS Switching Paths


Cisco IOS Switching Paths Overview

This chapter describes switching paths that can be configured on Cisco IOS devices. It contains the following sections:

• Basic Router Platform Architecture and Processes

• Basic Switching Paths

• Features That Affect Performance

Basic Router Platform Architecture and ProcessesTo understand how switching works, it helps to first understand the basic router architecture and where various processes occur in the router.

Fast switching is enabled by default on all interfaces that support fast switching. If you have a situation where you need to disable fast switching and fall back to the process-switching path, understanding how various processes affect the router and where they occur will help you determine your alternatives. This understanding is especially helpful when you are troubleshooting traffic problems or need to process packets that require special handling. Some diagnostic or control resources are not compatible with fast switching or come at the expense of processing and switching efficiency. Understanding the effects of those resources can help you minimize their effect on network performance.

Figure 2 illustrates a possible internal configuration of a Cisco 7500 series router. In this configuration, the Cisco 7500 series router has an integrated Route Switch Processor (RSP) and uses route caching to forward packets. The Cisco 7500 series router also uses Versatile Interface Processors (VIPs), a RISC-based interface processor that receives and caches routing information from the RSP. The VIP card uses the route cache to make switching decisions locally, which relieves the RSP of involvement and speeds overall throughput. This type of switching is called distributed switching. Multiple VIP cards can be installed in one router.

Cisco IOS Switching Paths OverviewBasic Router Platform Architecture and Processes


Figure 2 Basic Router Architecture

Cisco Routing and Switching ProcessesThe routing, or forwarding, function comprises two interrelated processes to move information in the network:

• Making a routing decision by routing

• Moving packets to the next hop destination by switching

Cisco IOS platforms perform both routing and switching, and there are several types of each.

Routing Processes

The routing process assesses the source and destination of traffic based on knowledge of network conditions. Routing functions identify the best path to use for moving the traffic to the destination out one or more of the router interfaces. The routing decision is based on various criteria such as link speed, topological distance, and protocol. Each protocol maintains its own routing information.

Routing is more processing intensive and has higher latency than switching as it determines path and next hop considerations. The first packet routed requires a lookup in the routing table to determine the route. The route cache is populated after the first packet is routed by the route-table lookup. Subsequent traffic for the same destination is switched using the routing information stored in the route cache.

ATM

Interfaceprocessors

EthernetFast Ethernet

Packetover Sonet

FrameRelay

FDDI

Routingprocessor

Switchingprocessor

S67

77

Cisco IOS Switching Paths OverviewBasic Router Platform Architecture and Processes


Figure 3 illustrates the basic routing process.

Figure 3 The Routing Process

A router sends routing updates out each of its interfaces that are configured for a particular protocol. It also receives routing updates from other attached routers. From these received updates and its knowledge of attached networks, it builds a map of the network topology.

Switching Processes

Through the switching process, the router determines the next hop toward the destination address. Switching moves traffic from an input interface to one or more output interfaces. Switching is optimized and has lower latency than routing because it can move packets, frames, or cells from buffer to buffer with simpler determination of the source and destination of the traffic. It saves resources because it does not involve extra lookups. Figure 4 illustrates the basic switching process.

Figure 4 The Switching Process

TokenRing

ATM

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78

FDDI

Router A

Router BRouter C

Router D

101

UpdateUpdate

Update

Update

Update

102

103 104

105

106

ATM

S67

79

FDDI

Router B

DataFDDIheader

102

103 104

DataEthernetheader

Data

Cisco IOS Switching Paths OverviewBasic Switching Paths


In Figure 4, packets are received on the Fast Ethernet interface and destined for the FDDI interface. Based on information in the packet header and destination information stored in the routing table, the router determines the destination interface. It looks in the routing table of the protocol to discover the destination interface that services the destination address of the packet.

The destination address is stored in tables such as ARP tables for IP or AARP tables for AppleTalk. If there is no entry for the destination, the router will either drop the packet (and inform the user if the protocol provides that feature) or discover the destination address by some other address resolution process, such as through ARP. Layer 3 IP addressing information is mapped to the Layer 2 MAC address for the next hop. Figure 5 illustrates the mapping that occurs to determine the next hop.

Figure 5 Layer 3-to-Layer 2 Mapping

Basic Switching PathsBasic switching paths are described in the following sections:

• Process Switching

• Fast Switching

• CEF Switching

• dCEF Switching

Process SwitchingIn process switching the first packet is copied to the system buffer. The router looks up the Layer 3 network address in the routing table and initializes the fast-switch cache. The frame is rewritten with the destination address and sent to the outgoing interface that services that destination. Subsequent packets for that destination are sent by the same switching path. The route processor computes the cyclical redundancy check (CRC).

Fast SwitchingWhen packets are fast switched, the first packet is copied to packet memory and the destination network or host is found in the fast-switching cache. The frame is rewritten and sent to the outgoing interface that services the destination. Subsequent packets for the same destination use the same switching path. The interface processor computes the CRC. Fast switching is described in the “Configuring Fast Switching” chapter later in this publication.

Wire

Layer 2 MAC address

Layer 3IP address

Next hop

S68

39

Cisco IOS Switching Paths OverviewBasic Switching Paths


CEF SwitchingWhen CEF mode is enabled, the CEF FIB and adjacency tables reside on the RP, and the RP performs the express forwarding. You can use CEF mode when line cards are not available for CEF switching or when you need to use features not compatible with dCEF switching. For information on configuring CEF, see the “Cisco Express Forwarding Overview” chapter later in this publication.

Note Beginning with Cisco IOS Release 12.0, CEF is the preferred and default switching path. NetFlow switching has been integrated into CEF switching. For information on NetFlow switching, see the “Cisco Express Forwarding Overview” chapter and the “Configuring Cisco Express Forwarding” chapter later in this publication.

dCEF SwitchingIn distributed switching, the switching process occurs on VIP and other interface cards that support switching. When dCEF is enabled, line cards, such as VIP line cards or GSR line cards, maintain an identical copy of the FIB and adjacency tables. The line cards perform the express forwarding between port adapters, relieving the RSP of involvement in the switching operation. dCEF uses an Inter Process Communication (IPC) mechanism to ensure synchronization of FIBs and adjacency tables on the RP and line cards.

For model numbers and hardware compatibility information, refer to the Cisco Product Catalog. For information on configuring dCEF, see the “Configuring Cisco Express Forwarding” chapter later in this publication.

For information on configuring Multicast Distributed Switching (MDS), see the “Configuring Multicast Distributed Switching” chapter later in this publication.

Figure 6 illustrates the distributed switching process on the Cisco 7500 series.

Figure 6 Distributed Switching on Cisco 7500 Series Routers

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VersatileInterface

Processor (VIP)

Interfaceprocessor

Interfaceprocessor

Route SwitchProcessor

(RSP)

Fast switching cache

Optimum switching cache

Fast switching

CyBus

Process switching (initialization)

Optimum switching

Switching types

Cisco IOS Switching Paths OverviewFeatures That Affect Performance


The VIP card installed in this router maintains a copy of the routing cache information needed to forward packets. Because the VIP card has the routing information it needs, it performs the switching locally, making the packet forwarding much faster. Router throughput is increased linearly based on the number of VIP cards installed in the router.

Platform and Switching Path Correlation

Depending on the routing platform you are using, availability and default implementations of switching paths varies. Table 3 shows the correlation between Cisco IOS switching paths and routing platforms.

Features That Affect PerformancePerformance is derived from the switching mechanism you are using. Some Cisco IOS features require special handling and cannot be switched until the additional processing they require has been performed. This special handling is not processing that the interface processors can do. Because these features require additional processing, they affect switching performance. These features include the following:

• Queueing

• Random Early Detection (RED)

• Compression

• Filtering (using access lists)

• Encryption

• Accounting

For information on Quality of Service (QoS) performance, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.

Table 3 Switching Paths on Cisco 7200 and Cisco 7500 Series Routers

Switching Path

Cisco 7200 Series

Cisco 7500 Series Comments Configuration Command

Process switching Yes Yes Initializes switching caches

no protocol route-cache

Fast switching Yes Yes Default (except for IP) protocol route-cache

CEF switching Yes Yes Default for IP protocol route-cache cef

dCEF switching No Yes Using second-generation VIP line cards

protocol route-cache cef distributed

Cisco IOS Switching Paths OverviewFeatures That Affect Performance


QueueingQueueing occurs when network congestion occurs. When traffic is moving well within the network, packets are sent as they arrive at the interface. Cisco IOS software implements four different queueing algorithms as follows:

• FIFO queueing—Packets are forwarded in the same order in which they arrive at the interface.

• Priority queueing (PQ)—Packets are forwarded based on an assigned priority. You can create priority lists and groups to define rules for assigning packets to priority queues.

• Custom queueing (CQ)—You can control a percentage of interface bandwidth for specified traffic by creating protocol queue lists and custom queue lists.

• Weighted fair queueing (WFQ)—WFQ provides automatic traffic priority management. Low-bandwidth sessions have priority over high-bandwidth sessions. High-bandwidth sessions are assigned weights. WFQ is the default for interfaces slower than 2.048 Mbps.

Random Early Detection (RED)RED is designed for congestion avoidance. Traffic is prioritized based on type of service (ToS), or precedence. This feature is available on T3, OC-3, and ATM interfaces.

CompressionDepending on the protocol you are using, various compression options are available in Cisco IOS software. Refer to the Cisco IOS configuration guide for the protocol you are using to learn compression options available.

FilteringYou can define access lists to control access to or from a router for a number of services. You could, for example, define an access list to prevent packets with a certain IP address from leaving a particular interface on a router. How access lists are used depends on the protocol. For information on access lists, refer to the appropriate Cisco IOS configuration guide for the protocol you are using.

EncryptionEncryption algorithms are applied to data to alter its appearance, making it incomprehensible to those not authorized to see the data. For information about encryption features available with the Cisco IOS software, refer to the Cisco IOS Security Configuration Guide.

AccountingYou can configure accounting features to collect network data related to resource usage. The information you collect (in the form of statistics) can be used for billing, chargeback, and planning resource usage. Refer to the appropriate Cisco IOS configuration guide for the protocol you are using for information regarding accounting features you can use.


Configuring Fast Switching

This chapter describes how to configure fast switching on Cisco IOS devices. It provides configuration guidelines for switching paths and tuning guidelines.

For a complete description of the commands in this chapter, refer to the the Cisco IOS Switching Services Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.

To identify the hardware platform or software image information associated with a feature, use the Feature Navigator on Cisco.com to search for information about the feature or refer to the software release notes for a specific release. For more information, see the section “Identifying Supported Platforms” in the chapter “Using Cisco IOS Software.”

Fast Switching Configuration Task ListFast switching allows higher throughput by switching a packet using a cache created by the initial packet sent to a particular destination. Destination addresses are stored in the high-speed cache to expedite forwarding. Routers offer better packet-transfer performance when fast switching is enabled. Fast switching is enabled by default on all interfaces that support fast switching.

To configure fast switching, perform the tasks described in the following sections:

• Enabling AppleTalk Fast Switching

• Enabling IP Fast Switching

• Enabling Fast Switching on the Same IP Interface

• Enabling Fast Switching of IPX Directed Broadcast Packets

• Enabling SMDS Fast Switching

Fast switching is not supported for the X.25 encapsulations.

Enabling AppleTalk Fast SwitchingAppleTalk access lists are automatically fast switched. Access list fast switching improves the performance of AppleTalk traffic when access lists are defined on an interface. Refer to the “Configuring AppleTalk” chapter in the Cisco IOS AppleTalk and Novell IPX Configuration Guide for guidelines on creating and using access lists and configuring AppleTalk.

Configuring Fast SwitchingFast Switching Configuration Task List


Enabling IP Fast SwitchingFast switching involves the use of a high-speed switching cache for IP routing. Destination IP addresses are stored in the high-speed cache to expedite packet forwarding. In some cases, fast switching is inappropriate, such as when slow-speed serial links (64K and below) are being fed from higher-speed media such as T1 or Ethernet. In such a case, disabling fast switching can reduce the packet drop rate to some extent. Fast switching allows outgoing packets to be load balanced on a per-destination basis.

To enable or disable fast switching, use the following commands in interface configuration mode:

Enabling Fast Switching on the Same IP InterfaceYou can enable IP fast switching when the input and output interfaces are the same interface. This normally is not recommended, though it is useful when you have partially meshed media such as Frame Relay. You could use this feature on other interfaces, although it is not recommended because it would interfere with redirection.

Figure 7 illustrates a scenario where enabling fast switching on the same IP interface is desirable. Router A has a data-link connection identifier (DLCI) to Router B, and Router B has a DLCI to Router C. There is no DLCI between Routers A and C; traffic between them must go in and out of Router B through the same interface.

Figure 7 IP Fast Switching on the Same Interface

To allow IP fast switching on the same interface, use the following command in interface configuration mode:

Command PurposeRouter(config-if)# ip route-cache Enables fast switching (use of a high-speed route cache for IP routing).

Router(config-if)# no ip route-cache Disables fast switching and enables load balancing on a per-packet basis.

Router C

Router A Router BFrame Relay

Network

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27a

Command Purpose

Router(config-if)# ip route-cache same-interface

Enables the fast switching of packets out of the same interface on which they arrived.

Configuring Fast SwitchingDisabling Fast Switching for Troubleshooting


Enabling Fast Switching of IPX Directed Broadcast PacketsBy default, Cisco IOS software switches IPX packets that have been directed to the broadcast address. To enable fast switching of these IPX-directed broadcast packets, use the following command in global configuration mode:

Enabling SMDS Fast SwitchingSMDS fast switching of IP, IPX, and AppleTalk packets provides faster packet transfer on serial links with speeds above 56 kbps. Use fast switching if you use high-speed, packet-switched, datagram-based WAN technologies such as Frame Relay offered by service providers.

By default, SMDS fast switching is enabled.

To reenable fast switching if it has been disabled, use the following commands in interface configuration mode:

Disabling Fast Switching for TroubleshootingFast switching uses a cache created by previous packets to achieve a higher packet throughput. Packet transfer performance is generally better when fast switching is enabled. Fast switching also provides load sharing on a per-destination basis.

By default, fast switching is enabled on all interfaces that support fast switching. However, you may want to disable fast switching to save memory space on interface cards and to help avoid congestion when high-bandwidth interfaces are writing large amounts of information to low-bandwidth interfaces. This is especially important when using rates slower than T1.

Fast switching is not supported on serial interfaces using encapsulations other than HDLC.

Note Turning off fast switching increases system overhead because the packets will be process switched by the system’s CPU.

Command PurposeRouter(config)# ipx broadcast-fastswitching

Enables fast switching of IPX directed broadcast packets.

Command Purpose

Step 1 Router(config-if)# interface type number

Defines the type and unit number of the interface, and enters interface configuration mode.

Step 2 Router(config-subif)# encapsulation smds

Sets SMDS encapsulation.

Step 3 Router(config-if)# ip route-cache Enables the interface for IP fast switching.

Step 4 Router(config-if)# ipx route-cache

Enables the interface for IPX fast switching.

Step 5 Router(config-if)# appletalk route-cache

Enables the interface for AppleTalk fast switching.

Configuring Fast SwitchingDisabling Fast Switching for Troubleshooting


For some diagnostics, such as debugging and packet-level tracing, you will need to disable fast switching. Disabling fast switching causes the router to fall back to process switching the packets. If fast switching is running, you might only see the first packet to each destination in the output of any packet-level debugging commands. Subsequent packets to the same destination will be fast switched. Many packet level debugging commands cannot process packets that are fast switched. You might want to turn off fast switching temporarily to use process switching instead while you are trying to capture information to diagnose a problem.

To disable fast switching, perform the tasks described in the following sections:

• Disabling AppleTalk Fast Switching

• Disabling Banyan VINES Fast Switching

• Disabling DECnet Fast Switching

• Disabling IPX Fast Switching

• Disabling ISO CLNS Fast Switching Through the Cache

• Disabling XNS Fast Switching

Disabling AppleTalk Fast SwitchingTo disable AppleTalk fast switching on an interface, use the following command in interface configuration mode:

Disabling Banyan VINES Fast SwitchingFast switching is enabled by default on all interfaces on which it is supported.

To disable fast switching on an interface, use the following command in interface configuration mode:

Disabling DECnet Fast Switching By default, DECnet routing software implements fast switching of DECnet packets.

To disable fast switching of DECnet packets, use the following command in interface configuration mode:

Command PurposeRouter(config-if)# no appletalk route-cache

Disables AppleTalk fast switching.

Command Purpose

Router(config-if)# no vines route-cache Disables fast switching.

Command Purpose

Router(config-if)# no decnet route-cache Disables fast switching of DECnet packets on a per-interface basis.

Configuring Fast SwitchingControlling the Route Cache


Disabling IPX Fast SwitchingTo disable IPX fast switching, use the following command in interface configuration mode:

Disabling ISO CLNS Fast Switching Through the CacheISO CLNS fast switching through the cache is enabled by default for all supported interfaces. To disable fast switching, use the following command in interface configuration mode:

Note The cache still exists and is used after the no clns route-cache interface configuration command is used; the software does not do fast switching through the cache.

Disabling XNS Fast Switching To disable XNS fast switching on an interface, use the following command in interface configuration mode:

Controlling the Route Cache The high-speed route cache used by IP fast switching is invalidated when the IP routing table changes. By default, the invalidation of the cache is delayed slightly to avoid excessive CPU load while the routing table is changing. To control the route cache, perform the tasks described in the following sections:

• Controlling Route Cache Invalidation for IP

• Displaying System and Network Statistics

• Adjusting the Route Cache for IPX

• Padding Odd-Length IPX Packets

Command PurposeRouter(config-if)# no ipx route-cache Disables IPX fast switching.

Command PurposeRouter(config-if)# no clns route-cache Disables fast switching.

Command Purpose

Router(config-if)# no xns route-cache Disables XNS fast switching.



Controlling Route Cache Invalidation for IPTo control route cache invalidation, use the following commands in global configuration mode as needed for your network:

Caution Normally, this task should not be necessary. It should be performed only under the guidance of technical staff. Incorrect configuration can seriously degrade the performance of your router.

Displaying System and Network StatisticsYou can display the contents of IP routing tables and caches. The resulting information can be used to determine resource utilization and to solve network problems.

To display system and network statistics, use the following command in privileged EXEC mode:

Adjusting the Route Cache for IPXAdjusting the route cache allows you to control the size of the route cache, reduce memory consumption, and improve router performance. You accomplish these tasks by controlling the route cache size and route cache invalidation. The following sections describe these optional tasks:

• Controlling IPX Route Cache Size (Optional)

• Controlling IPX Route Cache Invalidation (Optional)

Controlling IPX Route Cache Size

You can limit the number of entries stored in the IPX route cache to free up router memory and aid router processing.

Storing too many entries in the route cache can use a substantial amount of router memory, causing router processing to slow. This situation is most common on large networks that run network management applications for NetWare.

For example, if a network management station is responsible for managing all clients and servers in a very large (greater than 50,000 nodes) Novell network, the routers on the local segment can become inundated with route cache entries. You can set a maximum number of route cache entries on these routers to free up router memory and aid router processing.

Command PurposeRouter(config)# no ip cache-invalidate-delay

Allows immediate invalidation of the cache.

Router(config)# ip cache-invalidate-delay [minimum maximum quiet threshold]

Delays invalidation of the cache.

Command PurposeRouter# show ip cache [prefix mask] [type number] Displays the routing table cache used to fast switch IP

traffic.



To set a maximum limit on the number of entries in the IPX route cache, use the following command in global configuration mode:

If the route cache has more entries than the specified limit, the extra entries are not deleted. However, they may be removed if route cache invalidation is in use. See the “Controlling IPX Route Cache Invalidation” section in this chapter for more information on invalidating route cache entries.

Controlling IPX Route Cache Invalidation

You can configure the router to invalidate inactive fast-switch cache entries. If these entries remain invalidated for 1 minute, the router purges the entries from the route cache.

Purging invalidated entries reduces the size of the route cache, reduces memory consumption, and improves router performance. Purging entries also helps ensure accurate route cache information.

You specify the period of time that valid fast switch cache entries must be inactive before the router invalidates them. You can also specify the number of cache entries that the router can invalidate per minute.

To configure the router to invalidate fast-switch cache entries that are inactive, use the following command in global configuration mode:

When you use the ipx route-cache inactivity-timeout command with the ipx route-cache max-size global configuration command, you can ensure a small route cache with fresh entries.

Padding Odd-Length IPX PacketsSome IPX end hosts accept only even-length Ethernet packets. If the length of a packet is odd, the packet must be padded with an extra byte so that end host can receive it. By default, Cisco IOS software pads odd-length Ethernet packets.

However, there are cases in certain topologies where nonpadded Ethernet packets are forwarded onto a remote Ethernet network. Under specific conditions, you can enable padding on intermediate media as a temporary workaround for this problem. Note that you should perform this task only under the guidance of a customer engineer or other service representative.

Command Purpose

Router(config)# ipx route-cache max-size size Sets a maximum limit on the number of entries in the IPX route cache.

Command PurposeRouter(config)# ipx route-cache inactivity-timeout period [rate]

Invalidates fast switch cache entries that are inactive.



To enable the padding of odd-length packets, use the following commands in interface configuration mode:

Command Purpose

Step 1 Router(config-if)# no ipx route-cache Disables fast switching.

Step 2 Router(config-if)# ipx pad-process-switched-packets

Enables the padding of odd-length packets.


Cisco Express Forwarding Overview

Cisco Express Forwarding (CEF) is advanced, Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with large and dynamic traffic patterns, such as the Internet, on networks characterized by intensive Web-based applications, or interactive sessions.

Procedures for configuring CEF or distributed CEF (dCEF) are provided in the “Configuring Cisco Express Forwarding” chapter later in this publication.

This chapter describes CEF. It contains the following sections:

• Benefits

• Restrictions

• CEF Components

• Supported Media

• CEF Operation Modes

• TMS and CEF Nonrecursive Accounting

• Network Services Engine

• Virtual Profile CEF

BenefitsCEF offers the following benefits:

• Improved performance—CEF is less CPU-intensive than fast switching route caching. More CPU processing power can be dedicated to Layer 3 services such as quality of service (QoS) and encryption.

• Scalability—CEF offers full switching capacity at each line card when dCEF mode is active.

• Resilience—CEF offers an unprecedented level of switching consistency and stability in large dynamic networks. In dynamic networks, fast-switched cache entries are frequently invalidated due to routing changes. These changes can cause traffic to be process switched using the routing table, rather than fast switched using the route cache. Because the Forwarding Information Base (FIB) lookup table contains all known routes that exist in the routing table, it eliminates route cache maintenance and the fast-switch or process-switch forwarding scenario. CEF can switch traffic more efficiently than typical demand caching schemes.

Cisco Express Forwarding OverviewRestrictions


Although you can use CEF in any part of a network, it is designed for high-performance, highly resilient Layer 3 IP backbone switching. For example, Figure 8 shows CEF being run on Cisco 12000 series Gigabit Switch Routers (GSRs) at aggregation points at the core of a network where traffic levels are dense and performance is critical.

Figure 8 Cisco Express Forwarding

In a typical high-capacity Internet service provider (ISP) environment, Cisco 12012 GSRs as aggregation devices at the core of the network support links to Cisco 7500 series routers or other feeder devices. CEF in these platforms at the network core provides the performance and scalability needed to respond to continued growth and steadily increasing network traffic. CEF is a distributed switching mechanism that scales linearly with the number of interface cards and the bandwidth installed in the router.

Restrictions• The Cisco 12000 series Gigabit Switch Routers operate only in distributed CEF mode.

• Distributed CEF switching cannot be configured on the same VIP card as distributed fast switching.

• Distributed CEF is not supported on Cisco 7200 series routers.

• If you enable CEF and then create an access list that uses the log keyword, the packets that match the access list are not CEF switched. They are fast switched. Logging disables CEF.

CEF ComponentsInformation conventionally stored in a route cache is stored in several data structures for CEF switching. The data structures provide optimized lookup for efficient packet forwarding. The two main components of CEF operation are described in the following sections:

• Forwarding Information Base

• Adjacency Tables

CEF CEF

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Cisco Express Forwarding OverviewCEF Components


Forwarding Information BaseCEF uses a FIB to make IP destination prefix-based switching decisions. The FIB is conceptually similar to a routing table or information base. It maintains a mirror image of the forwarding information contained in the IP routing table. When routing or topology changes occur in the network, the IP routing table is updated, and those changes are reflected in the FIB. The FIB maintains next hop address information based on the information in the IP routing table.

Because there is a one-to-one correlation between FIB entries and routing table entries, the FIB contains all known routes and eliminates the need for route cache maintenance that is associated with switching paths such as fast switching and optimum switching.

Adjacency TablesNodes in the network are said to be adjacent if they can reach each other with a single hop across a link layer. In addition to the FIB, CEF uses adjacency tables to prepend Layer 2 addressing information. The adjacency table maintains Layer 2 next-hop addresses for all FIB entries.

Adjacency Discovery

The adjacency table is populated as adjacencies are discovered. Each time an adjacency entry is created (such as through ARP), a link-layer header for that adjacent node is precomputed and stored in the adjacency table. Once a route is determined, it points to a next hop and corresponding adjacency entry. It is subsequently used for encapsulation during CEF switching of packets.

Adjacency Resolution

A route might have several paths to a destination prefix, such as when a router is configured for simultaneous load balancing and redundancy. For each resolved path, a pointer is added for the adjacency corresponding to the next hop interface for that path. This mechanism is used for load balancing across several paths.

Adjacency Types That Require Special Handling

In addition to adjacencies associated with next hop interfaces (host-route adjacencies), other types of adjacencies are used to expedite switching when certain exception conditions exist. When the prefix is defined, prefixes requiring exception processing are cached with one of the special adjacencies listed in Table 4.

Table 4 Adjacency Types for Exception Processing

This adjacency type... Receives this processing...

Null adjacency Packets destined for a Null0 interface are dropped. This can be used as an effective form of access filtering.

Glean adjacency When a router is connected directly to several hosts, the FIB table on the router maintains a prefix for the subnet rather than for the individual host prefixes. The subnet prefix points to a glean adjacency. When packets need to be forwarded to a specific host, the adjacency database is gleaned for the specific prefix.

Cisco Express Forwarding OverviewSupported Media


Unresolved Adjacency

When a link-layer header is prepended to packets, the FIB requires the prepend to point to an adjacency corresponding to the next hop. If an adjacency was created by the FIB and not discovered through a mechanism, such as ARP, the Layer 2 addressing information is not known and the adjacency is considered incomplete. Once the Layer 2 information is known, the packet is forwarded to the Route Processor (RP), and the adjacency is determined through ARP.

Supported MediaCEF currently supports ATM/AAL5snap, ATM/AAL5mux, ATM/AAL5nlpid, Frame Relay, Ethernet, FDDI, PPP, HDLC, and tunnels.

CEF Operation ModesCEF can be enabled in one of two modes described in the following sections:

• Central CEF Mode

• Distributed CEF Mode

Punt adjacency Features that require special handling or features that are not yet supported in conjunction with CEF switching paths are forwarded to the next switching layer for handling. Features that are not supported are forwarded to the next higher switching level.

Discard adjacency Packets are discarded.

Drop adjacency Packets are dropped, but the prefix is checked.

Table 4 Adjacency Types for Exception Processing (continued)

This adjacency type... Receives this processing...

Cisco Express Forwarding OverviewCEF Operation Modes


Central CEF ModeWhen CEF mode is enabled, the CEF FIB and adjacency tables reside on the RP, and the RP performs the express forwarding. You can use CEF mode when line cards are not available for CEF switching or when you need to use features not compatible with dCEF switching.

Figure 9 shows the relationship between the routing table, FIB, and adjacency table during CEF mode. The Catalyst switches forward traffic from workgroup LANs to a Cisco 7500 series router on the enterprise backbone running CEF. The RP performs the express forwarding.

Figure 9 CEF Mode

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Cisco Express Forwarding OverviewCEF Operation Modes


Distributed CEF ModeWhen dCEF is enabled, line cards, such as VIP line cards or GSR line cards, maintain an identical copy of the FIB and adjacency tables. The line cards perform the express forwarding between port adapters, relieving the RSP of involvement in the switching operation.

dCEF uses an Inter Process Communication (IPC) mechanism to ensure synchronization of FIB tables and adjacency tables on the RP and line cards.

Figure 10 shows the relationship between the RP and line cards when dCEF mode is active.

Figure 10 dCEF Mode

In this Cisco 12000 series router, the line cards perform the switching. In other routers where you can mix various types of cards in the same router, all of the cards you are using may not support CEF. When a line card that does not support CEF receives a packet, the line card forwards the packet to the next higher switching layer (the RP) or forwards the packet to the next hop for processing. This structure allows legacy interface processors to exist in the router with newer interface processors.

Note The Cisco 12000 series GSR operate only in dCEF mode; dCEF switching cannot be configured on the same VIP card as distributed fast switching, and dCEF is not supported on Cisco 7200 series routers.

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Cisco Express Forwarding OverviewTMS and CEF Nonrecursive Accounting


CEF and dCEF Additional CapabilitiesIn addition to configuring CEF and dCEF, you can also configure the following features:

• Distributed CEF switching using access lists

• Distributed CEF switching of Frame Relay packets

• Distributed CEF switching during packet fragmentation

• Load balancing on a per-destination-source host pair or per-packet basis

• Distributed CEF switching across IP tunnels

For information on enabling these features, see the chapter “Configuring Cisco Express Forwarding.”

TMS and CEF Nonrecursive AccountingTraffic matrix statistics (TMS) data is counted during packet forwarding by CEF nonrecursive accounting. TMS enables an administrator to capture and analyze traffic data entering a backbone that is running the Border Gateway Protocol (BGP). This feature also allows an administrator to determine the neighbor autonomous systems of a BGP destination.

The following paragraphs explain how CEF nonrecursive accounting aggregates packet statistics for IGP routes and their dependent BGP routes.

For example, a BGP network deployed by a service provider has the following components:

• IGP routes that describe the next hop to which traffic should be sent.

• BGP routes that specify an intermediate address to which traffic should be sent.

In this example, the intermediate address might be several hops away. The next hop for the BGP route is the next hop for the intermediate address of the BGP route. The BGP route is called recursive, because it points (through its intermediate address) to an IGP route that provides the next hop for forwarding.

CEF represents IGP routes as nonrecursive entries and BGP routes as recursive entries that resolve to nonrecursive entries.

CEF nonrecursive accounting counts the packets for all the CEF recursive entries that resolve to a CEF nonrecursive entry and the packets for the nonrecursive entry. The number of packets is collected and totalled in one location.

The following example networks show how CEF nonrecursive accounting counts packets when BGP routes resolve to one IGP route and when they do not. A multiaccess network access point (NAP) has BGP routes referring to hosts on that network.

• If the network is advertised as a single IGP route, all the BGP routes to the various hosts at that NAP resolve to a single IGP route. CEF nonrecursive accounting summarizes the packets to all of the BGP destinations.

• If a network administrator instead advertises individual host routes from the NAP network to the IGP, CEF nonrecursive accounting will count packets to those hosts separately.

The count of packets forwarded based on a nonrecursive CEF entry can be split into two bins based on whether the input interface of the backbone router is configured as internal or external. Thus, all packets that arrive on external interfaces (external to the region of interest) and are forwarded based on a given IGP route (either directly or through a recursive BGP route) are counted together.



TMS DataThe TMS feature allows an administrator to gather the following data:

• The number of packets and bytes that travel across the backbone from internal and external sources. The packets and bytes are called traffic matrix statistics and are useful for determining how much traffic a backbone handles. You can analyze the traffic matrix statistics using the following methods:

– Collecting and viewing the TMS data through the application of the Network Data Analyzer (NDA).

– Reading the TMS data that resides on the backbone router.

The following sections explain how to collect and view the traffic matrix statistics using the command-line interface (CLI) and the NDA. For detailed instructions on using the NDA, see the Network Data Analyzer Installation and User Guide.

• The neighbor autonomous systems of a BGP destination. You can view the neighbor autonomous systems of a BGP destination by reading the tmasinfo_ascii file that resides on the backbone router.

How Backbone Routers Collect TMS DataBy enabling a backbone router to gather traffic matrix statistics, you can determine the amount of traffic that enters the backbone from sites outside of the backbone. You can also determine the amount of traffic that is generated within the backbone. The traffic matrix statistics help you optimize and manage traffic across the backbone.



Figure 11 shows a sample backbone, represented by darkly shaded routers and bold links. The lighter shaded and unshaded routers are outside the backbone. The traffic that travels through the backbone is the area of interest for TMS collection.

Figure 11 Network Backbone and Routers

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Figure 12 shows an exploded view of the backbone router that links the Los Angeles point of presence (POP) in Figure 11 to the Atlanta POP. The bold line represents the backbone link going to the Atlanta POP.

Figure 12 Traffic Traveling Through a Backbone Router

The following types of traffic travel through the backbone router shown in Figure 12:

• The dotted line marked A represents traffic entering the backbone from a router that is not part of the backbone. This is called external traffic.

• The dotted lines marked B and D represent traffic that is exiting the backbone. The router interprets traffic from paths B and D as being generated from within the backbone. This is called internal traffic.

• The dotted line marked C represents traffic that is not using the backbone and is not of interest to TMS.

You can determine the amount of traffic the backbone handles by enabling a backbone router to track the number of packets and bytes that travel through it. You can separate the traffic into the categories “internal” and “external.” You separate the traffic by designating incoming interfaces on the backbone router as internal or external.

Once you enable a backbone router to collect traffic matrix statistics, it starts free running counters, which dynamically update when network traffic passes through the backbone router. You can retrieve a snapshot of the traffic matrix statistics, either through a command to the backbone router or through the NDA.

External traffic (path A) is the most important for determining the amount of traffic. Internal traffic (paths B and D) is useful for ensuring that you are capturing all the TMS data. When you receive a snapshot of the traffic matrix statistics, the packets and bytes are displayed in internal and external categories.

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Viewing the TMS DataOnce TMS data is collected, you have the following options for viewing the data:

• Viewing the data in a graphical format, using the NDA Display module. The Display module is useful for graphing the traffic matrix data and comparing statistics. See the section “Viewing the TMS Data Through the NDA” for more information.

• Entering the more system:vfiles/tmstats_ascii EXEC command on the backbone router. This command displays a table of traffic matrix statistics. See the section “Viewing the TMS Data by Reading the Virtual Files that Reside on the Backbone Router” for more information.

• Entering the show ip cef EXEC command on the backbone router. This command displays nonrecursive accounting data for the backbone router. Included in the output is the number of packets and bytes of internal and external traffic that have been collected. See the section “Viewing TMS Data Through the show ip cef Command” for more information.

Viewing the TMS Data Through the NDA

The Network Data Analyzer collects TMS data from the backbone router and displays it using the NDA Display module. The TMS data can look similar to the data shown in Figure 13 and Figure 14. The display format depends on the aggregation scheme you selected. Refer to the Network Data Analyzer Installation and User Guide for more information.

(The NDA Display module is wide. You must slide the scroll bar to the right and left to see all of the data. Figure 13 and Figure 14 taken together show all the columns of data.)

Figure 13 Displaying TMS Data Through the NDA (Part 1)



Figure 14 Displaying TMS Data Through the NDA (Part 2)

Viewing the TMS Data by Reading the Virtual Files That Reside on the Backbone Router

You can read the TMS data that resides on the backbone router and is stored in the following virtual files:

• tmstats_ascii—TMS data in ASCII (human readable) format.

• tmstats_binary—TMS data in binary (space-efficient) format.

Reading the ASCII File

To view statistics in the ASCII file, enter the following command on the backbone router:

Router# more system:/vfiles/tmstats_ascii

Each file displayed consists of header information and records. A line of space follows the header and each record. A bar (|) separates consecutive fields within a header or record. The first field in a record specifies the type of record. The following example shows a sample TMSTATS_ASCII file:

VERSION 1|ADDR 172.27.32.24|AGGREGATION TrafficMatrix.ascii|SYSUPTIME 41428|routerUTC 3104467160|NTP unsynchronized|DURATION 1|p|10.1.0.0/16|242|1|50|2|100p|172.27.32.0/22|242|0|0|0|0

The following sections describe the header and the various types of records you can display.

File Header

The ASCII file header provides the address of the backbone router and information about how much time the router used to collect and export the TMS data. The header occupies one line and uses the following format:

VERSION 1|ADDR<address>|AGGREGATIONTrafficMatrix.ascii|SYSUPTIME<seconds>|routerUTC<routerUTC>|NTP<synchronized|unsynchronized>|DURATION<aggregateTime>|



Table 5 describes the fields in the file header of the TMSTATS_ASCII file.

Table 5 TMSTATS_ASCII File Header

Destination Prefix Record

The destination prefix record displays the internal and external packets and bytes for the IGP route and uses the following format:

p|<destPrefix/Mask>|<creationSysUpTime>|<internalPackets>|<internalBytes>|<externalPackets>|<externalBytes>

Table 6 describes the fields in the destination prefix record.

Table 6 Destination Prefix Record Fields

Tunnel Midpoint Record

The tunnel midpoint record displays the internal and external packets and bytes for the tunnel head and uses the following format:

t|<headAddr><tun_id>|<creationSysUpTime>|<internalPackets>|<internalBytes>|<externalPackets>|<externalBytes>

Maximum Field Length Field Description

10 VERSION File format version.

21 ADDR The IP address of the router.

32 AGGREGATION The type of data being aggregated.

21 SYSUPTIME The time of export (in seconds) since the router booted.

21 routerUTC The time of export (in seconds) since 1900-01-01 (Coordinated Universal Time (UTC)), as determined by the router.

19 NTP Whether Coordinated Universal Time (UTC) of the router has been synchronized by the Network Time Protocol (NTP).

20 DURATION The time needed to capture the data (in seconds).


2 <recordType> p means that the record represents dynamic label switching data or traffic engineered (TE) tunnel traffic data.

19 destPrefix/Mask The IP prefix address/mask (a.b.c.d/len format) for this IGP route.

11 creationSysUpTime The sysUpTime when the record was first created.

21 internalPackets Internal packet count.

21 internalBytes Internal byte count.

21 externalPackets External packet count.

20 externalBytes External byte count (no trailing |).



Table 7 describes the fields in the tunnel midpoint record.

Table 7 Tunnel Midpoint Record Fields

Reading the Binary File

The binary file tmstats_binary contains the same information as the ASCII file, except in a space-efficient format. You can copy this file from the router and read it with any utility that accepts files in binary format.

Viewing TMS Data Through the show ip cef Command

You can use the show ip cef EXEC command to display nonrecursive accounting information, including the internal and external packets and bytes that have traveled through the IP prefix address/mask (a.b.c.d/len format) for an IGP route.

router# show ip cef 192.168.1.8

192.168.1.8/32, version 220, per-destination sharing0 packets, 0 bytestag information setlocal tag:17via 192.168.67.8, FastEthernet6/0, 0 dependenciesnext hop 192.168.67.8, FastEthernet6/0valid adjacencytag rewrite with Fa6/0, 192.168.67.8, tags imposed {}1143 packets, 56702 bytes switched through the prefix30 second output rate 0 Kbits/sectmstats:external 0 packets, 0 bytesinternal 1144 packets, 56742 bytes

Viewing the BGP Neighbor Autonomous Systems

The TMS feature also displays the BGP neighbor autonomous system (AS) associated with each IGP destination. You can display all the neighbor autonomous systems for any IGP destination.

The tmasinfo file is in the ASCII format, which is the only one provided for this data. Enter the following command to read the tmasinfo file:

Router# more system:/vfiles/tmasinfo


2 <recordType> t means that the record represents TE tunnel midpoint data.

27 headAddr<space>tun_id The IP address of the tunnel head and tunnel interface number.

11 creationSysUpTime The sysUpTime when the record was first created.

21 internalPackets Internal packet count.

21 internalBytes Internal byte count.

21 externalPackets External packet count.

20 externalBytes External byte count (no trailing |).

Cisco Express Forwarding OverviewNetwork Services Engine


Each file consists of header information and a number of records. A line of space follows the header and each record. A bar (|) separates consecutive fields within a header or a record.

Header Format

The file header provides the address of the router and indicates how much time the router used to collect and export the data. The file header uses the following format:

VERSION 1|ADDR<address>|AGGREGATION ASList.ascii|SYSUPTIME<seconds>|routerUTC <routerUTC>|DURATION<aggregateTime>|

Table 8 describes the fields in the file header.

Table 8 TMASINFO File Header

Neighbor Autonomous System Record

The neighbor autonomous system record displays the neighbor autonomous system and the underlying prefix/mask for each BGP route. The record uses the following format:

<nonrecursivePrefix/Mask>|<AS>|<destinationPrefix/Mask>

Table 9 describes the fields in the neighbor autonomous system record.

Table 9 Neighbor Autonomous System Record Fields

Network Services EngineThe network services engine (NSE) is a processor engine for Cisco series routers. The NSE delivers wire rate OC-3 throughput while running concurrent high-touch WAN edge services. The NSE takes advantage of a new technology called Parallel eXpress Forwarding (PXF).

Note Before enabling the PXF processor, you must have IP routing and IP CEF switching turned on.

Max. Length Field Description

5 VERSION File format version.

15 ADDR The IP address of the router.

20 AGGREGATION The type of data being aggregated.

10 SYSUPTIME The time of export (in seconds) since router booted.

10 routerUTC The time of export (in seconds) since 1900-01-01, as determined by the router.

10 DURATION The time needed to capture the data (in seconds).


18 nonrecursivePrefix/Mask The IP prefix address/mask (a.b.c.d/len format) for this IGP route.

5 AS The neighbor autonomous system.

18 destinationPrefix/Mask The prefix/mask for the FIB entry (typically BGP route).

Cisco Express Forwarding OverviewVirtual Profile CEF


For information on configuring NSE, see the “Cisco Express Forwarding Overview” chapter later in this publication.

Network Services Engine benefits and requirements are as follows:

• Accelerated services—The following features are accelerated on the NSE: Network Address Translation (NAT), weighted fair queueing (WFQ), and NetFlow for both enterprise and service provider customers.

• PXF field upgradable—PXF is based on microcode and can be upgraded with new software features in future Cisco IOS releases.

The PXF processor enables IP parallel processing functions that work with the primary processor to provide accelerated IP Layer 3 feature processing. The PXF processor off-loads IP packet processing and switching functions from the RP to provide accelerated and highly consistent switching performance when coupled with one or more of several IP services features such as access Control Lists (ACLs), address translation, quality of service (QoS), flow accounting, and traffic shaping.

PXF offers the advantage of hardware-based switching power, plus the flexibility of a programmable architecture. The PXF architecture provides future-proofing—if additional features are added, an application-specific integrated circuit (ASIC) will not be required. New features for accelerated services can be added by reprogramming the PXF processor.

• System requirements—An NSE-1 can be used on existing Cisco 7200 VXR series routers with Cisco Release IOS 12.1(1)E or a later version of Cisco IOS Release 12.1 E, and with Cisco IOS Release 12.1(5)T or a later version of Cisco IOS Release 12.1 T.

• High performance—Network-layer services such as traffic management, security, and QoS benefit significantly from NSE-1 high-performance. NSE-1 is the first Cisco processing engine to offer integrated hardware acceleration, increasing Cisco 7200 VXR series system performance by 50 to 300 percent for combined “high-touch” WAN edge services.

Virtual Profile CEFThe Virtual Profile CEF feature allows you to enable asynchronous and ISDN interfaces in CEF switching. This feature allows you to create a datagram prefix and cache it in an adjacency table for fast reference and rewrite during the call setup. For information on configuring the Virtual Profile CEF feature, see the “Configuring Cisco Express Forwarding” chapter later in this publication.

Cisco Express Forwarding OverviewVirtual Profile CEF


Virtual Profile CEF benefits are as follows:

• FIB—Virtual Profile (VP) CEF switching allows the user to use the FIB to look up a route for a forwarding packet. Because the FIB is populated by routing topology, not by traffic, the FIB is a performance enhancement over cache tables used in fast switching.

• MPLS VPN/BGP integration—VP CEF switching enables VP to be used in other technologies that require CEF switching, such as MPLS Virtual Private Network/Border Gateway Protocol (VPN/BGP).

• ISDN interfaces—VP CEF allows you to enable ISDN interfaces in CEF switching.


Configuring Cisco Express Forwarding

This chapter describes the required and optional tasks for configuring Cisco Express Forwarding (CEF) and distributed CEF (dCEF).



Configuring CEFTo configure CEF, perform the tasks described in the following sections. The task in the first section is required; the tasks in the remaining sections are optional.

• Enabling CEF or dCEF (Required)

• Configuring Load Balancing for CEF (Optional)

• Configuring Network Accounting for CEF (Optional)

• Configuring Distributed Tunnel Switching for CEF (Optional)

• Configuring the Network Services Engine (Optional)

• Configuring Virtual Profile Switching for CEF (Optional)

• Verifying CEF (Optional)

• Troubleshooting Tips (Optional)

For an example configuration of IP CEF non-recursive accounting, refer to the “IP CEF Nonrecursive Accounting Example” section.

Configuring Cisco Express ForwardingConfiguring CEF


Enabling CEF or dCEFEnable CEF when your router has interface processors that do not support dCEF.

To enable CEF, use the following command in global configuration mode:

Enable dCEF when you want your line cards to perform express forwarding so that the route processor (RP) can handle routing protocols or switch packets from legacy interface processors.

Note On the Cisco 12000 series Internet router, dCEF is enabled by default. The command to enable dCEF is not available. Also, the configuration file does not indicate that dCEF is enabled on the router.

To enable or disable dCEF operation, use one of the following commands in global configuration mode as needed:

When you enable CEF or dCEF globally, all interfaces that support CEF are enabled by default. If you want to turn off CEF or dCEF on a particular interface, you can do so.

To disable CEF or dCEF on an interface, use the following command in interface configuration mode:

When you disable CEF or dCEF, Cisco IOS software switches packets received on the interface using the next fastest switching path. In the case of dCEF, the next fastest switching path is CEF on the RP.

If you have disabled CEF or dCEF operation on an interface and want to reenable it, you can do so by using the ip route-cache cef command in interface configuration mode.

Note On the Cisco 12000 series, you must not disable dCEF on an interface.

Command PurposeRouter(config)# ip cef Enables standard CEF operation.

Command PurposeRouter(config)# ip cef distributed Enables dCEF operation.

Router(config)# no ip cef distributed Disables dCEF operation.

Command Purpose

Router(config-if)# no ip route-cache cef Disables CEF operation on the interface.



Configuring Load Balancing for CEFCEF load balancing is based on a combination of source and destination packet information; it allows you to optimize resources by distributing traffic over multiple paths for transferring data to a destination.

You can configure load balancing on a per-destination or per-packet basis. Load balancing decisions are made on the outbound interface and so load balancing must be configured on the outbound interface.

Load distortions may occur across multiple routers when the same load balancing algorithm is used on every router. You can resolve these distortions by selecting a specific load balancing algorithm based on your network environment.

To configure and fine-tune load balancing for CEF, perform the optional tasks described in the following sections:

• Configuring per-Destination Load Balancing (Optional)

• Configuring per-Packet Load Balancing (Optional)

• Selecting a Load Balancing Algorithm (Optional)

Configuring per-Destination Load Balancing

Per-destination load balancing is enabled by default when you enable CEF. To use per-destination load balancing, you do not perform any additional tasks once you enable CEF.

Per-destination load balancing allows the router to use multiple paths to achieve load sharing. Packets for a given source-destination host pair are guaranteed to take the same path, even if multiple paths are available. Traffic destined for different pairs tend to take different paths. Per-destination load balancing is enabled by default when you enable CEF, and is the load balancing method of choice for most situations.

Because per-destination load balancing depends on the statistical distribution of traffic, load sharing becomes more effective as the number of source-destination pairs increase.

You can use per-destination load balancing to ensure that packets for a given host pair arrive in order. All packets for a certain host pair are routed over the same link (or links).

Disabling per-Destination Load Balancing

Typically, you would disable per-destination load balancing when you want to enable per-packet load balancing.

To disable per-destination load balancing, use the following command in interface configuration mode:

Command PurposeRouter(config-if)# no ip load-sharing per-destination

Disables per-destination load balancing.



Configuring per-Packet Load Balancing

Per-packet load balancing allows the router to send successive data packets over paths without regard to individual hosts or user sessions. It uses the round-robin method to determine which path each packet takes to the destination. Per-packet load balancing ensures balancing over multiple links.

Note Per-packet load balancing via CEF is not supported on Engine 2 Gigabit Switch Router (GSR) line cards (LCs).

Path utilization with per-packet load balancing is good for single path destinations, but packets for a given source-destination host pair might take different paths. Per-packet load balancing could introduce reordering of packets. This type of load balancing would be inappropriate for certain types of data traffic (such as voice traffic over IP) that depend on packets arriving at the destination in sequence.

Use per-packet load balancing to help ensure that a path for a single source-destination host pair does not get overloaded. If the bulk of the data passing through parallel links is for a single pair, per-destination load balancing will overload a single link while other links have very little traffic. Enabling per-packet load balancing allows you to use alternate paths to the same busy destination.

To enable per-packet load balancing, use the following command in interface configuration mode:

Note If you want to enable per-packet load balancing to a particular destination, all interfaces that can forward traffic to the destination must be enabled for per-packet load balancing.

Selecting a Load Balancing Algorithm

The router is set to perform universal load sharing by default. In universal load sharing, each router on the network can make a different load sharing decision for each source and destination address pair; thereby, resolving load sharing distortions. For example, the tunnel algorithm is designed to balance the per-packet load when only a few source and destination pairs are involved.

To select a load balancing algorithm, use one of the following commands in global configuration mode:

Command Purpose

Router(config-if)# ip load-sharing per-packet Enables per-packet load balancing.

Command Purpose

Router(config)# ip cef load-sharing algorithm original

Sets the load sharing algorithm to the original based on a source and destination hash.

Router(config)# ip cef load-sharing algorithm tunnel id

Sets the load sharing algorithm for use in tunnel environments or in environments where there are only a few IP source and destination address pairs.

Router(config)# ip cef load-sharing algorithm universal id

Sets the load sharing algorithm to the universal algorithm that uses a source and destination, and ID hash.



Configuring Network Accounting for CEFYou might want to collect statistics to better understand CEF patterns in your network. For example, you might want to collect information such as the number of packets and bytes switched to a destination or the number of packets switched through a destination.

To configure network accounting for CEF, perform the optional tasks described in the following sections:

• Enabling Network Accounting for CEF (Optional)

• Enabling a Backbone Router to Collect Traffic Matrix Statistics (TMS) Data (Optional)

• Verifying Network Accounting Information (Optional)

Enabling Network Accounting for CEF

To collect network accounting information for CEF, use one of the following commands in global configuration mode as needed:

When you enable network accounting for CEF from global configuration mode, accounting information is collected on the RP.

When you enable network accounting for dCEF from global configuration mode, accounting information grouped by IP prefix (recursive or nonrecursive) is not sent to the RP, but is collected on the line card.

To verify the statistics, use the show cef linecard command in privileged EXEC mode.

Enabling a Backbone Router to Collect Traffic Matrix Statistics (TMS) Data

The procedure for enabling a backbone router to collect TMS data includes enabling nonrecursive accounting and setting the interfaces on the router to collect internal or external traffic matrix statistics. The internal and external settings are used only for TMS collection. The interfaces are set to internal by default.

Note Make sure you set the incoming interfaces (not the outgoing ones) to collect internal and external traffic.

You can perform these tasks either through the command-line interface or through the Network Data Analyzer (NDA). The following sections explain each procedure.

Command PurposeRouter(config)# ip cef accounting per-prefix Enables the collection of the number of packets and bytes express

forwarded to a destination IP address (or prefix).

Router(config)# ip cef accounting non-recursive

Enables the collection of the number of packets express forwarded through a destination IP address.



To enable a backbone router to collect TMS data and separate internal and external traffic, use the following commands beginning in global configuration mode:

You can repeat Steps 3 and 4 for each incoming interface that you want to configure for TMS.

Using the NDA for TMS Data Collection

Use the NDA to enable TMS data collection and set the incoming interfaces on the backbone router to collect internal and external traffic. For specific instructions, refer to the Network Data Analyzer Installation and User Guide.

Enabling the NDA for TMS Data Collection

To enable TMS data collection, you must create a TMS collection and specify the following information:

• The name of the collection

• The router from which you want to collect TMS data

• How often and how long to collect TMS data

The window for enabling the collection of TMS data is similar to the one shown in Figure 15.

Command Purpose

Step 1 Router(config)# ip cef Enables CEF on the router.

Step 2 Router(config)# ip cef accounting non-recursive

Enables nonrecursive accounting on the router.

Step 3 Router(config)# interface type number

Specifies the interface on the backbone router that you intend to configure.

Step 4 Router(config-if)# ip cef accounting non-recursive external

or

Router(config-if)# ip cef accounting non-recursive internal

Sets the specified incoming interface so that it can collect traffic entering the backbone router from external sources.

Sets the specified incoming interface so that it can collect internal traffic in the backbone router.



Figure 15 Setting the NDA Traffic Matrix Statistics Control Window

Setting Internal and External Interfaces on the Router

The NDA Traffic Matrix Statistics Control window allows you to set the interfaces on the backbone router to collect internal and external packets and bytes as shown in Figure 16. By default, all interfaces are set to internal. Set the internal and external interfaces and click Apply. When the NDA asks if you want to enable CEF, click Yes.



Figure 16 Setting the NDA Configuration Window

Verifying Network Accounting Information

To view collected accounting information, use the following command in EXEC mode:

Configuring Distributed Tunnel Switching for CEFCEF supports distributed tunnel switching, such as GRE tunnels. Distributed tunnel switching is enabled automatically when you enable CEF or dCEF. You do not perform any additional tasks to enable distributed tunnel switching once you enable CEF or dCEF.

Command PurposeRouter# show ip cef Displays the collected accounting information.



Configuring the Network Services EngineThe Network Services Engine (NSE) or Parallel eXpress Forwarding (PXF) processor is turned on by default. If it is ever disabled, you must enable it to take advantage of IP packet switching and feature acceleration.

Note Before enabling the PXF processor, you must have IP routing and IP CEF switching turned on.

To configure the NSE, perform the tasks described in the following sections. The task in the first section is required; the tasks in the remaining sections are optional:

• Configuring the PXF Processor (Required)

• Verifying the PXF Processor (Optional)

• Troubleshooting the PXF Processor (Optional)

• Monitoring the PXF Processor (Optional)

Configuring the PXF Processor

To enable the PXF processor, use the following command in global configuration mode:

Verifying the PXF Processor

Enter the show pxf accounting command to view all the supported interfaces.

Router# show pxf accounting ?

ATM ATM interface Ethernet IEEE 802.3 FastEthernet FastEthernet IEEE 802.3 Hssi High Speed Serial Interface Null Null interface POS Packet over Sonet Serial Serial summary PXF summary statistics

Command Purpose

Router(config)# [no] ip pxf Enables PXF processing.



Troubleshooting the PXF Processor

Use the workarounds listed in Table 10 if you encounter an error message.

Monitoring the PXF Processor

To monitor PXF processors, use the following commands in privileged EXEC mode:

Table 10 PXF Error Messages

Error Message WorkaroundWARNING:PXF Exception:mac_xid=0x10000*** IHB watchdog timer expired6d16h:%PXF-2-EXCEPTION:pxf exception on pxf tmc.

Enter the show pxf crash EXEC command to obtain more information.

PXF processor hang and error message:WARNING:PXF Exception:mac_xid=0x8*** External Memory Column 3 exception, type = 20

This error message indicates that the PXF processor has been left in HALT state. During bootup, the PXF processor is in error state and cannot be brought up. To work around this problem, reload the router.

PXF processor crash and error message:00:49:37:Fatal pxf interrupt, int_reg=0x80, int_mask=0xFFFF, con-fig=0x1FF400000:49:37:-Traceback= 6055B9CC 60530D10

This message indicates that the PXF processor encountered a serious error and crashed. To work around this problem, reload the router.

Command Purpose

Router# show pxf accounting Displays PXF switching statistics for all interfaces.

Router# show pxf accounting ethernet Displays PXF switching statistics for Ethernet interfaces.

Router# show pxf accounting null Displays PXF switching statistics for NULL interfaces.

Router# show pxf accounting pos Displays PXF switching statistics for packet OC-3 interfaces.

Router# show pxf accounting serial Displays PXF switching statistics for serial interfaces.

Router# show pxf accounting summary Displays a summary of PXF switching statistics.

Router# show pxf crash Displays PXF crash information.

Router# show pxf feature cef Displays PXF routing feature tables for CEF.

Router# show pxf feature nat Displays PXF routing tables for NAT.

Router# show pxf interface Displays a summary of the interfaces in the router and the PXF features and capabilities that are enabled on these interfaces.



Configuring Virtual Profile Switching for CEFCEF supports virtual profile switching. Virtual profile switching is enabled automatically when you enable CEF. You do not perform any additional tasks to enable virtual profile switching once you enable CEF.

Verifying Virtual Profile Interfaces

To monitor and maintain virtual profile interfaces, use the following commands in privileged EXEC mode as needed:

Verifying CEFTo verify CEF-related information, use the following commands in privileged EXEC mode:

Command Purpose

Router# show adjacency detail Displays CEF adjacency table information.

Router# show ip cef Displays entries in the FIB that are unresolved or displays a summary of the FIB.

Router# show ip interfaces virtual-access number Displays network-layer IP information about a specified virtual access interface.

Command Purpose

Router# show cef Displays which packets the line cards dropped or displays which packets were not express forwarded.

Router# show cef interface Displays CEF-related interface information.

Router# show cef linecard Displays CEF-related interface information by line card.

Router# show ip cef adjacency Displays CEF recursive and direct prefixes resolved through an adjacency.

Router# show ip cef events Displays all recorded CEF FIB and adjacency events.

Router# show ip cef exact-route Displays the exact route for a source-destination IP address pair.

Router# show ip cef traffic prefix-length

Displays CEF traffic statistics.



Troubleshooting TipsCEF uses routing information that is retrieved from the Routing Information Base (RIB), Route Processor (RP), and the line card (LC) databases to perform express forwarding. As updates occur to these databases, inconsistencies may result due to the asynchronous nature of the distribution mechanism for these databases.

If you find a database inconsistency, such as an IP prefix missing from a line card or an RP; you can investigate and resolve these instances by referencing the CEF system error messages that occur and by issuing CEF debug and show commands.

For CEF consistency checker system error messages, refer to the System Error Messages for 12.2T in the “New Features in Release 12.2T” area of Cisco.com.

Enabling CEF Consistency Checkers

To enable CEF consistency checkers, use the following command in global configuration mode:

You can enable the following CEF consistency checker types:

• Lc-detect — Active line card checker to detect missing prefixes.

• Scan-lc — Passive scan checker of tables on a line card.

• Scan-rib — Passive scan checker of tables on an RP against the RIB.

• Scan-rp — Passive scan checker of tables on an RP.

Displaying CEF Table Inconsistencies

To display CEF table inconsistency records found by the lc-detect, scan-rp, scan-rib, and scan-lc detection mechanisms, use the following command in privileged EXEC mode:

Clearing CEF Table Inconsistencies

To clear CEF table inconsistencies, use the following commands in privileged EXEC mode:

Command PurposeRouter(config)# ip cef table consistency-check

Enables CEF table consistency checker types and parameters.

Command PurposeRouter# show ip cef inconsistency Displays CEF IP prefix inconsistencies.

Command Purpose

Router# clear ip cef inconsistency Clears CEF inconsistency statistics and records found by the CEF consistency checkers.

Router# clear cef linecard Clears CEF information from linecards.

Configuring Cisco Express ForwardingIP CEF Nonrecursive Accounting Example


IP CEF Nonrecursive Accounting ExampleThe following example shows how to enable routers to collect internal and external packets and bytes that travel through the backbone routers. Figure 17 shows the sample backbone configuration.

Figure 17 Sample Backbone Configuration

Router A ConfigurationRouter(config)# ip cefRouter(config)# ip cef accounting non-recursiveRouter(config)# interface e1/0Router(config-if)# ip cef accounting non-recursive external

Router B Configuration: e1/1Router(config)# ip cefRouter(config)# ip cef accounting non-recursiveRouter(config)# interface e1/1Router(config-if)# ip cef accounting non-recursive external

Router B Configuration: e1/0Router(config)# interface e1/0Router(config-if)# ip cef accounting non-recursive internal

Router C Configuration: e1/1:Router(config)# ip cefRouter(config)# ip cef accounting non-recursiveRouter(config)# interface e1/1Router(config-if)# ip cef accounting non-recursive internal

Router C Configuration: e1/0Router(config)# interface e1/0Router(config-if)# ip cef accounting non-recursive external

Router D ConfigurationRouter(config)# ip cefRouter(config)# ip cef accounting non-recursiveRouter(config)# interface e1/1Router(config-if)# ip cef accounting non-recursive external

Router Ce1/1 e1/0

(internal) (external)

Router Ae1/0

(external)

Router Be1/1 e1/0

(external) (internal)

Router De1/1

(external)

4716

2

NetFlow Switching


NetFlow Overview

Release 12.2April 30, 2001

NetFlow provides network administrators with access to call detail recording information from their data networks. Exported NetFlow data can be used for a variety of purposes, including network management and planning, enterprise accounting and departmental chargebacks, ISP billing, data warehousing, and data mining for marketing purposes. NetFlow also provides a highly efficient mechanism with which to process security access lists without paying as much of a performance penalty as is incurred with other available switching methods.

Procedures for configuring NetFlow are provided in the “Configuring NetFlow” chapter later in this publication.

This chapter describes NetFlow. It contains the following sections:

• Accounting Statistics

• NetFlow Data Format

• NetFlow Aggregation

• NetFlow Policy Routing

Accounting StatisticsNetFlow is a technology that captures as part of its switching function a rich set of traffic statistics. These traffic statistics include user, protocol, port, and type of service (ToS) information that can be used for a wide variety of purposes such as network analysis and planning, accounting, and billing.

NetFlow is supported on IP and IP encapsulated traffic over all interface types and encapsulations except for ISL/VLAN, ATM, and Frame Relay interfaces when more than one input Access Control List is used on the interface, and ATM LANE.

Capturing Traffic DataIn conventional switching at the network layer, each incoming packet is handled on an individual basis with a series of functions to perform access list checks, capture accounting data, and switch the packet. With NetFlow, after a flow has been identified and access list processing of the first packet in the flow has been performed, all subsequent packets are handled on a connection-oriented basis as part of the flow, where access list checks are bypassed, and packet switching and statistics capture are performed in tandem.

NetFlow OverviewNetFlow Data Format


A network flow is identified as a unidirectional stream of packets between a given source and destination—both defined by a network-layer IP address and transport-layer port number. Specifically, a flow is identified as the combination of the following fields:

• Source IP address

• Destination IP address

• Source port number

• Destination port number

• Protocol type

• Type of service

• Input interface

NetFlow CacheNetFlow operates by creating a flow cache that contains the information needed to switch and perform access list checking for all active flows. The NetFlow cache is built by processing the first packet of a flow through the standard switching path. As a result, each flow is associated with an incoming and outgoing interface port number and with a specific security access permission and encryption policy. The cache also includes entries for traffic statistics that are updated in tandem with the switching of subsequent packets. After the NetFlow cache is created, packets identified as belonging to an existing flow can be switched based on the cached information and security access list checks bypassed. Flow information is maintained within the NetFlow cache for all active flows.

NetFlow Data FormatNetFlow exports flow information in UDP datagrams in one of two formats. The version 1 format was the initially released version, and version 5 is a later enhancement to add Border Gateway Protocol (BGP) autonomous system (AS) information and flow sequence numbers. Versions 2 through 4 were not released.

In version 1 and version 5 formats, the datagram consists of a header and one or more flow records. The first field of the header contain the version number of the export datagram. Typically, a receiving application that accepts either format allocates a buffer large enough for the largest possible datagram from either format and uses the version from the header to determine how to interpret the datagram. The second field in the header is the number of records in the datagram and should be used to index through the records.

All fields in either version 1 or version 5 formats are in network byte order. Table 11 and Table 12 describe the data format for version 1, and Table 13 and Table 14 describe the data format for version 5.

We recommend that receiving applications check datagrams to ensure that the datagrams are from a valid NetFlow source. We recommend that you first check the size of the datagram to make sure it is at least long enough to contain the version and count fields. Next we recommend that you verify that the version is valid (1 or 5) and that the number of received bytes is enough for the header and count flow records (using the appropriate version).



Because NetFlow export uses UDP to send export datagrams, it is possible for datagrams to be lost. To determine whether or flow export information is lost, the version 5 header format contains a flow sequence number. The sequence number is equal to the sequence number of the previous datagram plus the number of flows in the previous datagram. After receiving a new datagram, the receiving application can subtract the expected sequence number from the sequence number in the header to get the number of missed flows.

Table 11 lists the bytes for the version 1 header format.

Table 12 lists the byte definitions for version 1 flow record format.

Table 11 Version 1 Header Format

Bytes Content Description

0 to 3 version and count Netflow export format version number and number of flows exported in this packet (1 to 24).

4 to 7 SysUptime Current time (in milliseconds) since router booted.

8 to 11 unix_secs Current seconds since 0000 UTC 1970.

12 to 15 unix_nsecs Residual nanoseconds since 0000 UTC 1970.

Table 12 Version 1 Flow Record Format


0 to 3 srcaddr Source IP address.

4 to 7 dstaddr Destination IP address.

8 to 11 nexthop IP address of the next hop router.

12 to 15 input and output SNMP index of the input and output interface.

16 to 19 dPkts Packets in the flow.

20 to 23 dOctets Total number of Layer 3 bytes in the flow’s packets.

24 to 27 First SysUptime at start of flow.

28 to 31 Last SysUptime at the time the last packet of flow was received.

32 to 35 srcport and dstport TCP/UDP source and destination port number or equivalent.

36 to 39 pad1, prot, and tos Unused (zero) byte, IP protocol (for example, 6 = TCP, 17 = UDP), and IP ToS.

40 to 43 flags, pad2, and pad3 Cumulative OR of TCP flags. Pad 2 and pad 3 are unused (zero) bytes.

44 to 47 reserved Unused (zero) bytes.



Table 13 lists the byte definitions for the version 5 header format.

Table 14 lists the byte definitions for the version 5 flow record format.

Table 13 Version 5 Header Format


0 to 3 version and count Netflow export format version number and number of flows exported in this packet (1 to 30).

4 to 7 SysUptime Current time (in milliseconds) since the router booted

8 to 11 unix_secs Current seconds since 0000 UTC 1970.

12 to 15 unix_nsecs Residual nanoseconds since 0000 UTC 1970.

16 to 19 flow_sequence Sequence counter of total flows seen.

20 to 23 reserved Unused (zero) bytes.

Table 14 Version 5 Flow Record Format


0 to 3 srcaddr Source IP address.

4 to 7 dstaddr Destination IP address.

8 to 11 nexthop IP address of the next hop router.

12 to 15 input and output SNMP index of the input and output interface.

16 to 19 dPkts Packets in the flow.

20 to 23 dOctets Total number of Layer 3 bytes in the flow’s packets.

24 to 27 First SysUptime at start of flow.

28 to 31 Last SysUptime at the time the last packet of flow was received.

32 to 35 srcport and dstport TCP/UDP source and destination port number or equivalent.

36 to 39 pad1, tcp_flags, prot, and tos

Unused (zero) byte, Cumulative OR of TCP flags, IP protocol (for example, 6 = TCP, 17 = UDP), and IP ToS.

40 to 43 src_as and dst_as Autonomous system of the source and destination, either origin or peer.

44 to 47 src_mask, dst_mask, and pad2

Source and destination address prefix mask bits. Pad 2 is unused (zero) bytes.

NetFlow OverviewNetFlow Aggregation


NetFlow AggregationBy maintaining one or more extra flow caches, called aggregation caches, the NetFlow Aggregation feature allows limited aggregation of NetFlow data export streams on a router.

Note To collect NetFlow version 8 data export records, use NetFlow FlowCollector version 3.0. Version 2.0 and earlier versions do not support version 8 data export record formats.

BenefitsThe NetFlow Aggregation feature provides the following benefits:

• Reduced bandwidth requirement—NetFlow aggregation caches reduce the bandwidth required between routers and NetFlow management workstations.

• Reduced NetFlow workstation requirements—NetFlow aggregation caches reduce the number of NetFlow management workstations required.

• Improved router scalability—NetFlow aggregation caches improve the scalability of high-flow-per-second routers, such as the Cisco 7500 series.

Aggregation Cache SchemesThe aggregation cache schemes are described in the following sections:

• Autonomous System Aggregation Scheme

• Destination Prefix Aggregation Scheme

• Prefix Aggregation Scheme

• Protocol Port Aggregation Scheme

• Source Prefix Aggregation Scheme

• Aggregation Scheme Fields and Key Fields

You can configure each aggregation cache with its individual cache size, cache ager timeout parameter, export destination IP address, and export destination UDP port. As data flows expire in the main NetFlow cache, the flows are added to each enabled aggregation cache. Each aggregation cache contains different field combinations that determine which data flows are grouped. The default aggregation cache size is 4096.

Table 15 lists definitions for the data export record terms used in each aggregation scheme.

Table 15 Data Export Record Terms and Definitions

Term Definition

Bytes Number of bytes in the aggregated flows.

Destination BGP autonomous system Peer or origin autonomous system of the destination prefix (IP address.)

Destination interface SNMP index of the output interface.

Destination port Destination UDP or TCP port number.



Destination prefix Destination IP address ANDed with the destination prefix mask.

First System uptime when the first packet was switched.

Flows Number of main cache flows that were aggregated.

Last System uptime when the last packet was switched.

Packets Number of packets in the aggregated flows.

PAD Zero field.

Protocol IP protocol byte.

Source BGP autonomous system Peer or origin autonomous system of the source prefix.

Source interface SNMP index of the input interface.

Source port Source UDP or TCP port number if applicable.

Source prefix Source IP address ANDed with the source prefix mask, or the prefix that the source IP address of the aggregated flows belong to.

Table 15 Data Export Record Terms and Definitions (continued)

Term Definition



Autonomous System Aggregation Scheme

The Autonomous System aggregation scheme provides substantial NetFlow export data volume reduction and generates autonomous system-to-autonomous system traffic flow data. The scheme groups data flows with the same source BGP autonomous system, destination BGP autonomous system, input interface, and output interface. See Figure 18.

The aggregated NetFlow data export records report the following:

• Source and destination BGP autonomous system

• Number of packets summarized by the aggregated record

• Number of flows summarized by the aggregated record

• Number of bytes summarized by the aggregated record

• Output and input interfaces

• Time stamp when the first packet is switched and time stamp when the last packet is switched

Figure 18 Autonomous System Aggregation Data Export Format

Last time stamp

Source AS

Source interface

First time stamp

Bytes

Packets

Flows

Destination interface

Destination AS

2646

2

0

4

8

12

16

20

24

0

4

8

12

16

20

24



Destination Prefix Aggregation Scheme

The Destination Prefix aggregation scheme generates data so that you can examine the destinations of network traffic passing through a NetFlow-enabled device. The scheme groups data flows with the same destination prefix, destination prefix mask, destination BGP autonomous system, and output interface. See Figure 19.


• Destination prefix

• Destination prefix mask

• Destination BGP autonomous system




• Output interface


Figure 19 Destination Prefix Aggregation Data Export Record Format

Destination prefix

PADDestination mask

bits

Destination interface

First time stamp

Last time stamp

Bytes

Packets

Flows0

4

8

12

16

20

24

28 Reserved

Destination AS46

3

0

4

8

12

16

20

24



Prefix Aggregation Scheme

The Prefix aggregation scheme generates data so that you can examine the sources and destinations of network traffic passing through a NetFlow-enabled device. The scheme groups data flows with the same source prefix, destination prefix, source prefix mask, destination prefix mask, source BGP autonomous system, destination BGP autonomous system, input interface, and output interface. See Figure 20.


• Source and destination prefix

• Source and destination prefix mask

• Source and destination BGP autonomous system




• Input and output interface


Figure 20 Prefix Aggregation Data Export Record Format

Source prefix

Destination prefix

Destination maskbits

Source maskbits

Source AS

First time stamp

Last time stamp

Bytes

Packets

Flows

Destination AS

Source interface Destination interface

Reserved

2646

4

0

4

8

12

16

20

24

28

32

36

0

4

8

12

16

20

24

28

32

36



Protocol Port Aggregation Scheme

The Protocol Port aggregation scheme generates data so that you can examine network usage by traffic type. The scheme groups data flows with the same IP protocol, source port number, and destination port number when applicable. See Figure 21.


• Source and destination port numbers

• IP protocol (where 6 = TCP, 17 = UDP, and so on)





Figure 21 Protocol Port Aggregation Data Export Record Format

PADProtocol

Source port

First time stamp

Last time stamp

Bytes

Packets

Flows

Destination port

Reserved

2646

5

0

4

8

12

16

20

24

0

4

8

12

16

20

24



Source Prefix Aggregation Scheme

The Source Prefix aggregation scheme generates data so that you can examine the sources of network traffic passing through a NetFlow-enabled device. The scheme groups data flows with the same source prefix, source prefix mask, source BGP autonomous system, and input interface. See Figure 22.


• Source prefix

• Source prefix mask

• Source BGP autonomous system



• Input interface


Figure 22 Source Prefix Aggregation Data Export Record Format

PADSource maskbits

Source interface

First time stamp

Last time stamp

Source prefix

Bytes

Packets

Flows

Reserved

Source AS26

466

0

4

8

12

16

20

24

28

0

4

8

12

16

20

24

28



Aggregation Scheme Fields and Key Fields

To coordinate flow aggregation on your router, determine the fields from which you want to collect data. Table 16 shows which fields are valid for the different aggregation schemes and which fields are part of the keys. Key fields define a unique flow.

Table 16 Aggregation Scheme Data Fields

Data Fields Aggregation Schemes

Autonomous System

Destination Prefix Prefix

Protocol Port Source Prefix

Source Prefix

Destination Prefix

Protocol *

Type of Service Byte

Source Port *

Destination Port *

Source Interface * * *

Destination Interface * * *

OR’d TCP Flags

Source BGP Autonomous System

* * *

Destination BGP Autonomous System

* * *

Source Prefix Mask * *

Destination Prefix Mask * *

Next Hop IP Adress

Source Encap Bytes

Destination Encap Bytes

Source Prefix * *

Destination Prefix * *

First Timestamp x x x x x

Last Timestamp x x x x x

Flows x x x x x

Packets x x x x x

Bytes x x x x x

* = exported key field

x = exported field



New Version 8 NetFlow Data Export Support

NetFlow exports flow information in UDP datagrams in one of several formats. Version 8, a new data export version, has been added to support data exports from aggregation caches. Version 8 allows for export datagrams to contain a subset of the usual version 5 export data, which is valid for a particular aggregation scheme type.

Figure 23 shows the version 8 header with the version and time stamp information. Table 17 lists definitions for terms used in the version 8 header.

Figure 23 Version 8 Header Format

Setting a NetFlow Minimum Mask

The NetFlow Minimum Prefix Mask for Router Based Aggregation feature allows the user to set a minimum mask size. The IP address that is added to the aggregation cache is ANDed with the maximum of the two masks: user-entered mask and the routing table mask.

Table 17 Terms and Definitions for Version 8 Headers

Term Definition

Version The flow export format version number. In this case, the number is “8.”

Count The number of export records in the datagram.

System uptime The number of milliseconds since the router was last booted.

UNIX seconds The number of seconds since 0000 UTC 1970.

UNIX nanoseconds The number of residual nanoseconds since 0000UTC 1970.

Sequence number Sequence counter of total flows sent for this export stream.

Engine type The type of switching engine. RP = 0 and LC = 1.

Engine ID The slot number of the NetFlow engine.

Aggregation The type of aggregation scheme being used.

Aggregation version The aggregation subformat version number. The current value is “2.”

Engine IDEngine type

Reserved

UNIX seconds

UNIX nanoseconds

Sequence number

System uptime

CountVersion

Aggregation Aggregationversion

2646

7

0

4

8

12

16

20

24

NetFlow OverviewNetFlow Policy Routing


To enable this feature for a particular aggregation cache, configure the desired minimum mask value using the NetFlow aggregation cache commands. The minimum mask value used by the router selects the granularity of the NetFlow data that will be collected as follows:

• For coarse NetFlow collection granularity, select a low minimum mask value.

• For fine NetFlow collection granularity, select a high minimum mask value.

The mask values range from 1 to 32.

Note Setting a NetFlow minimum mask size is not available in Autonomous System aggregation and Protocol Port aggregation.

NetFlow Policy RoutingNetFlow policy routing (NPR) integrates policy routing, which enables traffic engineering and traffic classification, with NetFlow services, which provide billing, capacity planning, and monitoring information on real-time traffic flows. IP policy routing now works with Cisco Express Forwarding (CEF), Distributed CEF (dCEF), and NetFlow.

As quality of service (QoS) and traffic engineering become more popular, so does interest in the ability of policy routing to selectively set IP precedence and type of service (TOS) bits (based on access lists and packet size), thereby routing packets based on predefined policy. It is important that policy routing work well in large, dynamic routing environments. Hence, distributed support allows you to leverage your investment in distributed architecture.

Cisco IOS introduced three technologies for IP Policy Routing. See Table 18.

NPR leverages these technologies. To configure NetFlow policy routing, see the chapter “Configuring NetFlow” in this publication.

BenefitsNetFlow policy routing provides the following benefits:

• NPR takes advantage of the new switching services. CEF, dCEF, and NetFlow can now use policy routing.

• Now that policy routing is integrated into CEF, policy routing can be deployed on a wide scale and on high-speed interfaces.

Table 18 Three Technologies for IP Policy Routing

Technology Description

CEF Looks at a Forwarding Information Base (FIB) table instead of a routing table when switching packets.

dCEF Addresses the scalability and maintenance problems of a demand caching scheme.

NetFlow A Cisco IOS software accounting tool for network planning, accounting, billing and security.

NetFlow OverviewNetFlow Policy Routing


RestrictionsNetFlow policy routing has the following restrictions:

• NPR is only available on Cisco IOS CEF-based platforms.

• Distributed FIB-based policy routing is only available on platforms that support dCEF and images that support dCEF.

• dCEF—The set ip next-hop verify-availability route-map configuration command is not supported in dCEF because dCEF does not support the Cisco Discovery Protocol (CDP) database.


Configuring NetFlow

This chapter describes how to configure NetFlow data accounting on your routing devices.


To identify the hardware platform or software image information associated with a feature, use the Feature Navigator on Cisco.com to search for information about the feature or refer to the software release notes for a specific release. For more information, see the section “Finding Support Information for Platforms and Cisco IOS Software Images” in the chapter “Using Cisco IOS Software.”

What is NetFlow?NetFlow enables you to collect traffic flow statistics on your routing devices. NetFlow is based on identifying packet flows for ingress IP packets. It does not involve any connection-setup protocol either between routers or to any other networking device or end station and does not require any change externally—either to the traffic or packets themselves or to any other networking device. NetFlow is completely transparent to the existing network, including end stations and application software and network devices like LAN switches. Also, NetFlow is performed independently on each internetworking device, it need not be operational on each router in the network. Using NetFlow Data Export (NDE), you can export data to a remote workstation for data collection and further processing. Network planners can selectively invoke NDE on a router or on a per-subinterface basis to gain traffic performance, control, or accounting benefits in specific network locations.

http://lbj.cisco.com/targets/ucdit/cc/td/doc/product/software/ios123/123cgcr/preface/gusing.htm#wp1008791

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Configuring NetFlowNetFlow Configuration Task List


Note NetFlow does consume additional memory and CPU resources; therefore, it is important to understand the resources required on your router before enabling NetFlow.

NetFlow Configuration Task ListTo configure NetFlow, perform the tasks described in the following sections. The task in the first section is required; the remaining tasks are optional.

• Enabling NetFlow (Required)

• Exporting NetFlow Statistics (Optional)

• Customizing the Number of Entries in the NetFlow Cache (Optional)

• Managing NetFlow Statistics (Optional)

• Configuring IP Distributed and NetFlow on VIP Interfaces (Optional)

• Configuring an Aggregation Cache (Optional)

• Configuring a NetFlow Minimum Prefix Mask for Router-Based Aggregation (Optional)

• Configuring NetFlow Policy Routing (Optional)

Enabling NetFlowTo enable NetFlow, first configure the router for IP routing as described in the IP configuration chapters in the Cisco IOS IP Configuration Guide, Volume 2 of 3: Routing Protocols. After you configure IP routing, use the following commands beginning in global configuration mode:

Command Purpose

Step 1 Router(config)# interface type slot/port-adapter/port (Cisco 7500 series routers)

or

Router(config)# interface type slot/port (Cisco 7200 series routers)

Specifies the interface, and enter interface configuration mode.

Step 2 Router(config-if)# ip route-cache flow Enables NetFlow for IP routing.



Exporting NetFlow StatisticsNetFlow information can also be exported to network management applications. To configure the router to export NetFlow statistics maintained in the NetFlow cache to a workstation when a flow expires, use either of the following commands in global configuration mode:

Customizing the Number of Entries in the NetFlow CacheNormally the size of the NetFlow cache will meet your needs. However, you can increase or decrease the number of entries maintained in the cache to meet the needs of your NetFlow traffic rates. The default is 64K flow cache entries. Each cache entry requires about 64 bytes of storage. Assuming a cache with the default number of entries, about 4 MB of DRAM would be required. Each time a new flow is taken from the free flow queue, the number of free flows is checked. If only a few free flows remain, NetFlow attempts to age 30 flows using an accelerated timeout. If only one free flow remains, NetFlow automatically ages 30 flows regardless of their age. The intent is to ensure that free flow entries are always available.

To customize the number of entries in the NetFlow cache, use the following command in global configuration mode:

Command PurposeRouter(config)# ip flow-export ip-address udp-port [version 1]

Configures the router to export NetFlow cache entries to a workstation if you are using receiving software that requires version 1. Version 1 is the default.

Router(config)# ip flow-export ip-address udp-port version 5 [origin-as | peer-as]

Configures the router to export NetFlow cache entries to a workstation if you are using receiving software that accepts version 5. Optionally specify the origin or peer autonomous system. The default is to export neither AS that provides improved performance.

Caution Entering the ip flow-export or no ip flow-export command on the Cisco 12000 Series Internet Routers and specifying any version format other than version 1 (in other words, entering the ip flow-export or no ip flow-export command and specifying either the version 5 or version 9 keyword) causes packet forwarding to stop for a few seconds while NetFlow reloads the route processor and line card CEF tables. To avoid interruption of service to a live network, apply this command during a change window, or include it in the startup-config file to be executed during a router reboot.

Command Purpose

Router(config)# ip flow-cache entries number Changes the number of entries maintained in the NetFlow cache. The number of entries can be from 1024 to 524288. The default is 65536.



Caution We recommend that you not change the NetFlow cache entries. Improper use of this feature could cause network problems. To return to the default NetFlow cache entries, use the no ip flow-cache entries global configuration command.

Managing NetFlow StatisticsYou can display and clear NetFlow statistics. NetFlow statistics consist of IP packet size distribution, IP flow cache information, and flow information such as the protocol, total flow, flows per second, and so on. The resulting information can be used to determine information about your router traffic. To manage NetFlow statistics, use the following commands in privileged EXEC mode as needed:

Configuring IP Distributed and NetFlow on VIP InterfacesOn Cisco 7500 series routers with a Route Switch Processor (RSP) and with Versatile Interface Processor (VIP) controllers, the VIP hardware can be configured to switch packets received by the VIP with no per-packet intervention on the part of the RSP. This process is called distributed switching. Distributed switching decreases the demand on the RSP.

The VIP hardware can also be configured for NetFlow, a high-performance feature that caches information about the flow. NetFlow data can also be exported to network management applications.

Refer to the Cisco Product Catalog for information about VIP port adapters used for distributed switching.

To configure distributed switching on the VIP, first configure the router for IP routing as described in this chapter and the various routing protocol chapters, depending on the protocols you use. After you configure IP routing, use the following commands beginning in global configuration mode:

Command PurposeRouter# show ip cache flow Displays the NetFlow statistics.

Router# clear ip flow stats Clears the NetFlow statistics.

Command Purpose

Step 1 Router(config)# interface type slot/port-adapter/port

Specifies the interface, and enters interface configuration mode.

Step 2 Router(config-if)# ip route-cache distributed Enables VIP distributed switching of IP packets on the interface.

Step 3 Router(config-if)# ip route-cache flow Enables NetFlow.



To export NetFlow cache entries to a workstation when a flow expires, use the following command in global configuration mode:

Configuring an Aggregation CacheTo configure an aggregation cache, you must enter aggregation cache configuration mode, and you must decide which type of aggregation scheme you would like to configure: Autonomous System, Destination Prefix, Prefix, Protocol Prefix, or Source Prefix aggregation cache. Once you define the aggregation scheme, define the operational parameters for that scheme:

Verifying Aggregation Cache Configuration and Data Export

To verify the aggregation cache information, use the following command in EXEC mode:

To confirm data export, use the following command in EXEC mode:

Configuring a NetFlow Minimum Prefix Mask for Router-Based Aggregation

Command Purpose

Router(config)# ip flow-export ip-address udp-port Configures the router to export NetFlow cache entries to a workstation.

Command Purpose

Step 1 Router(config)# ip flow-aggregation cache as Enters aggregation cache configuration mode and enables an aggregation cache scheme (as, destination-prefix, prefix, protocol-port, or source-prefix).

Step 2 Router(config-flow-cache)# cache entries 2046 Specifies the number (in this example, 2046) of cache entries to allocate for the Autonomous System aggregation cache.

Step 3 Router(config-flow-cache)# cache timeout inactive 199

Specifies the number of seconds (in this example, 199) that an inactive entry is allowed to remain in the aggregation cache before it is deleted.

Step 4 Router(config-flow-cache)# cache timeout active 45

Specifies the number of minutes (in this example, 45) that an active entry is active.

Step 5 Router(config-flow-cache)# export destination 10.42.41.1 9991

Enables the data export.

Step 6 Router(config-flow-cache)# enabled Enables aggregation cache creation.

Command Purpose

Router# show ip cache flow aggregation Displays the aggregation cache information.

Command Purpose

Router# show ip flow export Displays the statistics for the data export including the main cache and all other enabled caches.



To configure NetFlow Minimum Prefix Mask for Router-Based Aggregation feature, perform the tasks described in the following sections. Each task is optional.

• Configuring the Minimum Mask of a Prefix Aggregation Scheme (Optional)

• Configuring the Minimum Mask of a Destination-Prefix Aggregation Scheme (Optional)

• Configuring the Minimum Mask of a Source-Prefix Aggregation Scheme (Optional)

Per form the following section to verify your NetFlow aggregation configuration:

• Monitoring and Maintaining Minimum Masks for Aggregation Schemes (Optional)

Configuring the Minimum Mask of a Prefix Aggregation SchemeTo configure the minimum mask of a prefix aggregation scheme, use the following commands beginning in aggregation cache configuration mode:

Configuring the Minimum Mask of a Destination-Prefix Aggregation SchemeTo configure the minimum mask of a destination-prefix aggregation scheme, use the following commands beginning in aggregation cache configuration mode:

Configuring the Minimum Mask of a Source-Prefix Aggregation SchemeTo configure the minimum mask of a source-prefix aggregation scheme, use the following commands beginning in aggregation cache configuration mode:

Command Purpose

Step 1 Router(config)# ip flow-aggregation cache prefix Configures the prefix aggregation cache.

Step 2 Router(config-flow-cache)# mask source minimum value Specifies the minimum value for the source mask.

Step 3 Router(config-flow-cache)# mask destination minimum value Specifies minimum value for the destination mask.

Command Purpose

Step 1 Router(config)# ip flow-aggregation cache destination-prefix Configures the destination aggregation cache.

Step 2 Router(config-flow-cache)# mask destination minimum value Specifies the minimum value for the destination mask.

Command Purpose

Step 1 Router(config)# ip flow-aggregation cache source-prefix Configures the source-prefix aggregation cache.

Step 2 Router(config-flow-cache)# mask source minimum value Specifies the minimum value for the source mask.



Monitoring and Maintaining Minimum Masks for Aggregation SchemesTo view the configured value of the minimum mask, use the following commands for each aggregation scheme in EXEC mode, as needed:

Note If the minimum mask has not been explicitly configured, no minimum mask information is displayed. The default value of the minimum mask is zero. The configurable range for the minimum mask is from 1 to 32. An appropriate value should be chosen by the user depending on the traffic. A higher value of the minimum mask will provide more detailed network addresses, but it may also result in increased number of flows in the aggregation cache.

Configuring NetFlow Policy RoutingAs long as policy routing is configured, NetFlow policy routing (NPR) is enabled by default and cannot be disabled. That is, NPR is the default policy routing mode. No configuration tasks are required to enable policy routing in conjunction with CEF or dCEF. As soon as one of these features is turned on, packets are automatically subject to policy routing in the appropriate switching path.

There is one optional configuration command (set ip next-hop verify-availability route-map configuration command). This command has the following restrictions:

• It can cause some performance degradation.

• CDP must be configured on the interface.

• The direct next hop must be a Cisco device with CDP enabled.

• It is not available in dCEF due to the dependency of the CDP neighbor database.

It is assumed that policy routing itself is already configured.

If the router is policy routing packets to the next hop and the next hop happens to be down, the router will try unsuccessfully to use Address Resolution Protocol (ARP) for the next hop (which is down). This behavior will continue forever.

To prevent this situation, you can configure the router to first verify that the next hops of the route map are CDP neighbors of the router before routing to that next hop.

Command PurposeRouter# show ip cache flow aggregation prefix Displays the configured value of the

minimum mask in the prefix aggregation scheme.

Router# show ip cache flow aggregation destination-prefix Displays the configured value of the minimum mask in the destination-prefix aggregation scheme.

Router# show ip cache flow aggregation source-prefix Displays the configured value of the minimum mask in the source-prefix aggregation scheme.

Configuring NetFlowNetFlow Configuration Examples


This task is optional because some media or encapsulations do not support CDP, or it may not be a Cisco device that is sending the router traffic.

To configure the router to verify that the next hop is a CDP neighbor before the router tries to policy route to it, use the following command in route-map configuration mode:

If the command shown is set and the next hop is not a CDP neighbor, the router looks to the subsequent next hop, if there is one. If there is none, the packets simply are not policy routed.

If the command shown is not set, the packets are either successfully policy routed or remain forever unrouted.

If you want to selectively verify availability of only some next hops, you can configure different route-map entries (under the same route-map name) with different criteria (using access list matching or packet size matching), and use the set ip next-hop verify-availability route-map configuration command selectively.

Monitoring NetFlow Policy Routing

Typically, you would use existing policy routing and NetFlow show EXEC commands to monitor these features. For more information on these show commands, refer to the policy routing and NetFlow documentation.

To display the route map Inter Processor Communication (IPC) message statistics in the RP or VIP, use the following command in EXEC mode:

NetFlow Configuration ExamplesThis section provides the following basic configuration examples:

• NetFlow Configuration Example

• NetFlow Aggregation Configuration Examples

• Setting a NetFlow Minimum Prefix Mask for Router-Based Aggregation Examples

NetFlow Configuration ExampleThe following example shows how to modify the configuration of serial interface 3/0/0 to enable NetFlow and to export the flow statistics for further processing to UDP port 0 on a workstation with the IP address of 1.1.15.1. In this example, existing NetFlow statistics are cleared to ensure accurate information when the show ip cache flow command in privileged EXEC mode is entered to view a summary of the NetFlow statistics.

Command PurposeRouter(config-route-map)# set ip next-hop verify-availability

Causes the router to confirm that the next hops of the route map are CDP neighbors of the router.

Command Purpose

Router# show route-map ipc Displays the route map IPC message statistics in the RP or VIP.



configure terminalinterface serial 3/0/0ip route-cache flowexitip flow-export 1.1.15.1 0 version 5 peer-asexitclear ip flow stats

The following is a sample display of a main cache using the show ip cache flow command:

Router# show ip cache flow

IP packet size distribution (230151 total packets): 1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480 .999 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

512 544 576 1024 1536 2048 2560 3072 3584 4096 4608 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

The preceding output shows the percentage distribution of packets by size range. In this display, 99.9 percent of the packets fall in the size range from 1 to 32 bytes.

IP Flow Switching Cache, 4456448 bytes 65509 active, 27 inactive, 820628747 added 955454490 ager polls, 0 flow alloc failures Exporting flows to 1.1.15.1 (2057) 820563238 flows exported in 34485239 udp datagrams, 0 failed last clearing of statistics 00:00:03

Protocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)-------- Flows /Sec /Flow /Pkt /Sec /Flow /FlowTCP-BGP 71 0.0 1 49 0.0 2.5 15.8UDP-other 17 0.0 1 328 0.0 0.0 15.7ICMP 18966 6.7 10 28 72.9 0.1 22.9Total: 19054 6.7 10 28 72.9 0.1 22.9

SrcIf SrcIPaddress DstIf DstIPaddress Pr TOS Flgs PktsPort Msk AS Port Msk AS NextHop B/Pk ActiveEt1/1 52.52.52.1 Fd4/0 42.42.42.1 01 55 10 3748 0000 /8 50 0000 /8 40 202.120.130.2 28 17.8Et1/2 52.52.52.1 Fd4/0 42.42.42.1 01 CC 10 3568 0000 /8 50 0000 /8 40 202.120.130.2 28 17.8Et1/2 10.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1124 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 11.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1157 0000 /0 0 0000 /8 40 202.120.130.2 28 17.7Et1/2 14.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1149 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 15.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1127 0000 /0 0 0000 /8 40 202.120.130.2 28 17.7Et1/2 12.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1204 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 13.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1159 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 18.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1223 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 19.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1264 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 16.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1170 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 17.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1167 0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 22.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1193



0000 /0 0 0000 /8 40 202.120.130.2 28 17.8Et1/2 23.1.3.2 Fd4/0 42.42.42.1 01 C0 10 1212 0000 /0 0 0000 /8 40 202.120.130.2 28 17.7Et1/1 50.50.50.1 Local 31.31.31.1 06 C0 18 2 00B3 /32 0 2AF8 /32 0 0.0.0.0 49 10.1Et1/0 8.8.8.8 Et0/0* 9.9.9.9 01 00 10 3 0000 /8 302 0800 /8 300 3.3.3.3 100 0.1

Note The very last entry in the “DstIf” field has an asterisk (*) next to the destination interface. The asterisk (*) immediately following the “DstIf” field indicates that the flow being shown is an egress flow.

Table 19 describes the significant fields shown in the flow switching cache lines of the display.

Table 20 describes the significant fields shown in the activity by protocol lines of the display.

Table 19 show ip cache flow Field Descriptions in Flow Switching Cache Display

Field Description

bytes Number of bytes of memory used by the NetFlow cache.

active Number of active flows in the NetFlow cache at the time this command was entered.

inactive Number of flow buffers that are allocated in the NetFlow cache, but were not currently assigned to a specific flow at the time this command was entered.

added Number of flows created since the start of the summary period.

ager polls Number of times the NetFlow code looked at the cache to cause entries to expire (used by Cisco for diagnostics only).

flow alloc failures Number of times the NetFlow code tried to allocate a flow but could not.

Exporting flows IP address and User Datagram Protocol (UDP) port number of the workstation to which flows are exported.

flows exported in udp datagrams

Total number of flows exported and the total number of UDP datagrams used to export the flows to the workstation.

failed Number of flows that could not be exported by the router because of output interface limitations.

last clearing of statistics Standard time output (hh:mm:ss) since the clear ip flow stats privileged EXEC command was executed. This time output changes to hours and days after the time exceeds 24 hours.

Table 20 show ip cache flow Field Descriptions in Activity by Protocol Display

Field Description

Protocol IP protocol and the well-known port number as described in RFC 1340.

Total Flows Number of flows for this protocol since the last time statistics were cleared.

Flows/Sec Average number of flows for this protocol seen per second; equal to total flows/number of seconds for this summary period.



Table 21 describes the significant fields in the NetFlow record lines of the display.

Packets/Flow Average number of packets observed for the flows seen for this protocol. Equal to total packets for this protocol or number of flows for this protocol for this summary period.

Bytes/Pkt Average number of bytes observed for the packets seen for this protocol (total bytes for this protocol or total number of packet for this protocol for this summary period).

Packets/Sec Average number of packets for this protocol per second (total packets for this protocol) or total number of seconds for this summary period.

Active(Sec)/Flow Sum of all the seconds from the first packet to the last packet of an expired flow (for example, TCP FIN, timeout, and so on), in seconds or total flows for this protocol for this summary period.

Idle(Sec)/Flow Sum of all the seconds from the last packet seen in each nonexpired flow for this protocol until the time at which this command was entered, in seconds or total flows for this protocol for this summary period.

Table 20 show ip cache flow Field Descriptions in Activity by Protocol Display (continued)

Field Description

Table 21 show ip cache verbose flow Field Descriptions in NetFlow Record Display

Field Description

SrcIf Interface on which the packet was received.

Port Msk AS Source Border Gateway Protocol (BGP) autonomous system. This is always set to 0 in MPLS flows.

SrcIPaddress IP address of the device that transmitted the packet.

DstIf Interface from which the packet was transmitted. Note The DstIf interface can be reported as “Null” if the packets are any of

the following:

• Blocked by an ACL

• Process-switched

• Multicast traffic

• Locally-generated traffic

• Tunnels (IPIP, GRE, IPSEC, L2TP)

• Web Cache Communication Protocol (WCCP)

• Using a static route to a Null0 interface

• Dropped by Quality of Service (QoS) rules (for example, Committed Access Rate or Policing)

The following rules apply to QoS traffic:

• The DstIf information is correct if the traffic is not dropped by QoS

• The DstIf will be reported as “Null” when the traffic is dropped due to QoS rules.

Port Msk AS Destination BGP autonomous system. This is always set to 0 in MPLS flows.



NetFlow Aggregation Configuration ExamplesThis section provides the following aggregation cache configuration examples:

• Autonomous System Configuration Example

• Destination Prefix Configuration Example

• Prefix Configuration Example

• Protocol Port Configuration Example

• Source Prefix Configuration Example

Autonomous System Configuration Example

The following example shows how to configure an Autonomous System aggregation cache with a cache size of 2046, an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:

Router(config)# ip flow-aggregation cache asRouter(config-flow-cache)# cache entries 2046Router(config-flow-cache)# cache timeout inactive 200Router(config-flow-cache)# cache timeout active 45Router(config-flow-cache)# export destination 10.42.42.1 9992Router(config-flow-cache)# enabled

Destination Prefix Configuration Example

The following example shows how to configure a Destination Prefix aggregation cache with a cache size of 2046, an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:

Router(config)# ip flow-aggregation cache destination-prefixRouter(config-flow-cache)# cache entries 2046Router(config-flow-cache)# cache timeout inactive 200Router(config-flow-cache)# cache timeout active 45Router(config-flow-cache)# export destination 10.42.42.1 9992Router(config-flow-cache)# enabled

DstIPaddress IP address of the destination device.

NextHop Specifies the BGP next-hop address. This is always set to 0 in MPLS flows.

Pr IP protocol well-known port number as described in RFC 1340, displayed in hexadecimal format.

B/Pk Average number of bytes observed for the packets seen for this protocol (total bytes for this protocol or the total number of flows for this protocol for this summary period).

Flgs TCP flags (result of bitwise OR of TCP flags from all packets in the flow).

Active Number of active flows in the NetFlow cache at the time this command was entered.

Pkts Number of packets switched through this flow.

Table 21 show ip cache verbose flow Field Descriptions in NetFlow Record Display (continued)

Field Description



Prefix Configuration Example

The following example shows how to configure a Prefix aggregation cache with a cache size of 2046, an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:

Router(config)# ip flow-aggregation cache prefixRouter(config-flow-cache)# cache entries 2046Router(config-flow-cache)# cache timeout inactive 200Router(config-flow-cache)# cache timeout active 45Router(config-flow-cache)# export destination 10.42.42.1 9992Router(config-flow-cache)# enabled

Protocol Port Configuration Example

The following example shows how to configure a Protocol Port aggregation cache with a cache size of 2046, an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:

Router(config)# ip flow-aggregation cache protocol-portRouter(config-flow-cache)# cache entries 2046Router(config-flow-cache)# cache timeout inactive 200Router(config-flow-cache)# cache timeout active 45Router(config-flow-cache)# export destination 10.42.42.1 9992Router(config-flow-cache)# enabled

Source Prefix Configuration Example

The following example shows how to configure a Source Prefix aggregation cache with a cache size of 2046, an inactive timeout of 200 seconds, a cache active timeout of 45 minutes, an export destination IP address of 10.42.42.1, and a destination port of 9992:

Router(config)# ip flow-aggregation cache source-prefixRouter(config-flow-cache)# cache entries 2046Router(config-flow-cache)# cache timeout inactive 200Router(config-flow-cache)# cache timeout active 45Router(config-flow-cache)# export destination 10.42.42.1 9992Router(config-flow-cache)# enabled

Setting a NetFlow Minimum Prefix Mask for Router-Based Aggregation Examples

This section provides the following NetFlow minimum prefix mask aggregation cache configuration examples:

• Prefix Aggregation Scheme Example

• Destination-Prefix Aggregation Scheme Example

• Source-Prefix Aggregation Scheme Example

Prefix Aggregation Scheme Example

!ip flow-aggregation cache prefixmask source minimum 24



mask destination minimum 28

Destination-Prefix Aggregation Scheme Example

!ip flow-aggregation cache destination-prefixmask destination minimum 32!

Source-Prefix Aggregation Scheme Example

ip flow-aggregation cache source-prefixmask source minimum 30!

NetFlow Policy Routing ExampleThe following example configures CEF and NetFlow. It also configures policy routing to verify that next hop 50.0.0.8 of route map named test is a CDP neighbor before the router tries to policy route to it.

If the first packet is being policy routed via route map test sequence 10, the subsequent packets of the same flow always take the same route map test sequence 10, not route map test sequence 20, because they all match or pass access list 1 check.

ip cefinterface ethernet0/0/1ip route-cache flowip policy route-map test

route-map test permit 10match ip address 1set ip precedence priorityset ip next-hop 50.0.0.8set ip next-hop verify-availability

route-map test permit 20match ip address 101set interface Ethernet0/0/3set ip tos max-throughput

Multiprotocol Label Switching


Multiprotocol Label Switching Overview

This chapter describes the Multiprotocol Label Switching (MPLS) distribution protocol. MPLS is a high-performance packet forwarding technology that integrates the performance and traffic management capabilities of data link layer (Layer 2) switching with the scalability, flexibility, and performance of network-layer (Layer 3) routing. It enables service providers to meet challenges brought about by explosive growth and provides the opportunity for differentiated services without necessitating the sacrifice of existing infrastructure.

The MPLS architecture is remarkable for its flexibility:

• Data can be transferred over any combination of Layer 2 technologies

• Support is offered for all Layer 3 protocols

• Scaling is possible well beyond anything offered in today’s networks.

Specifically, MPLS can efficiently enable the delivery of IP services over an ATM switched network. It supports the creation of different routes between a source and a destination on a purely router-based Internet backbone. Service providers who use MPLS can save money and increase revenue and productivity.

Procedures for configuring MPLS are provided in the “Configuring Multiprotocol Label Switching” chapter later in this publication.

Note Label switching on a router requires that Cisco Express Forwarding (CEF) be enabled on that router. Refer to the CEF feature documentation for configuration information. For more information on enabling CEF, see the “Configuring Cisco Express Forwarding” chapter in this publication.

This chapter describes MPLS. It contains the following sections:

• MPLS/Tag Switching Terminology

• MPLS Commands and Saved Configurations

• MPLS/Tag Switching CLI Command Summary

• Benefits

• Label Switching Functions

• Distribution of Label Bindings

• MPLS and Routing

• MPLS Traffic Engineering

• MPLS Virtual Private Networks

Multiprotocol Label Switching OverviewMPLS/Tag Switching Terminology


• MPLS Quality of Service

• MPLS Label Switch Controller

• MPLS Egress NetFlow Accounting

MPLS/Tag Switching TerminologyBeginning with Cisco IOS Release 12.1, the Tag Switching distribution protocol has been replaced with the MPLS distribution protocol. MPLS supports the following:

• Tag Switching features

• Tag Switching command-line interface (CLI) commands

Table 22 lists tag switching terms (found in earlier releases of this document) and the equivalent MPLS terms used in this document.

MPLS Commands and Saved ConfigurationsDuring the transition period from tag switching to MPLS, if a configuration command has both MPLS and tag switching forms, the tag switching version is written to saved configurations. For example, you can configure MPLS hop-by-hop forwarding for a router POS interface by issuing the following commands:

Router# configure terminalRouter(config)# interface POS3/0

Table 22 Equivalency Table for Tag Switching and MPLS Terms

Old Tag Switching Terminology New MPLS Terminology

Tag Switching Multiprotocol Label Switching (MPLS)

Tag (short for Tag Switching) MPLS

Tag (item or packet) Label

TDP (Tag Distribution Protocol) LDP (Label Distribution Protocol)

Cisco TDP and LDP (MPLS Label Distribution Protocol) are nearly identical in function, but use incompatible message formats and some different procedures. Cisco is changing from TDP to a fully compliant LDP.

Tag Switched Label Switched

TFIB (Tag Forwarding Information Base)

LFIB (Label Forwarding Information Base)

TSR (Tag Switching Router) LSR (Label Switching Router)

TSC (Tag Switch Controller) LSC (Label Switch Controller)

ATM-TSR (ATM Tag Switch Router) ATM-LSR (ATM Label Switch Router, such as the Cisco BPX 8650 switch)

TVC (Tag VC, Tag Virtual Circuit) LVC (Label VC, Label Virtual Circuit)

TSP (Tag Switch Path) LSP (Label Switch Path)

XTag ATM (extended Tag ATM port) XmplsATM (extended MPLS ATM port)

Multiprotocol Label Switching OverviewMPLS/Tag Switching CLI Command Summary


Router(config-if)# mpls ip

In this example, the mpls ip command has a tag switching form (tag-switching ip). After you enter these commands and save this configuration or display the running configuration by means of the show running configuration command, the configuration commands appear as follows:

interface POS3/0tag-switching ip

Saving the tag switching form of commands (that have both tag switching and MPLS forms) allows for backward compatibility. You can use a new router software image to modify and write configurations, and then later use configurations created by the new image with earlier software versions that do not support the MPLS forms of commands

Using the tag switching forms of the commands allows older software that supports tag switching commands, but not new MPLS commands, to successfully interpret interface configurations.

MPLS/Tag Switching CLI Command SummaryTable 23 summarizes general-purpose MPLS commands. Except where otherwise noted, these MPLS commands have been derived from existing tag-switching commands to preserve the familiar syntax of existing commands that formed the basis for implementing new MPLS functionality.

Table 23 Summary of MPLS Commands Described in this Document

CommandCorresponding Tag Switching Command Description

debug mpls adjacency debug tag-switching adjacency Displays changes to label switching entries in the adjacency database.

debug mpls events debug tag-switching events Displays information about significant MPLS events.

debug mpls lfib cef debug tag-switching tfib cef Prints detailed information about label rewrites being created, resolved, and deactivated as CEF routes are added, changed, or removed.

debug mpls lfib enc debug tag-switching tfib enc Prints detailed information about label encapsulations while label rewrites are created or updated and placed into the label forwarding information base (LFIB).

debug mpls lfib lsp debug tag-switching tfib tsp Prints detailed information about label rewrites being created and deleted as TSP tunnels are added or removed.

debug mpls lfib state debug tag-switching tfib state Traces what happens when label switching is enabled or disabled.

debug mpls lfib struct debug tag-switching tfib struct Traces the allocation and freeing of LFIB-related data structures, such as the LFIB itself, label-rewrites, and label-info data.

debug mpls packets debug tag-switching packets Displays labeled packets switched by the host router.

interface atm interface atm Enters interface configuration mode, specifies ATM as the interface type, and enables the creation of a subinterface on the ATM interface.

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Multiprotocol Label Switching OverviewBenefits


BenefitsMPLS provides the following major benefits to service provider networks:

• Scalable support for SVirtual Private Networks (VPNs)—MPLS enables VPN services to be supported in service provider networks, thereby greatly accelerating Internet growth.

The use of MPLS for VPNs provides an attractive alternative to the building of VPNs by means of either ATM or Frame Relay permanent virtual circuits (PVCs) or various forms of tunneling to interconnect routers at customer sites.

Unlike the PVC VPN model, the MPLS VPN model is highly scalable and can accommodate increasing numbers of sites and customers. The MPLS VPN model also supports “any-to-any” communication among VPN sites without requiring a full mesh of PVCs or the backhauling

mpls atm control-vc tag-switching atm control-vc Configures the VPI and VCI to be used for the initial link to the label switching peer device.

mpls atm vpi tag-switching atm vpi Configures the range of values to be used in the VPI field for label VCs.

mpls ip (global configuration) tag-switching ip (global configuration)

Enables MPLS forwarding of IPv4 packets along normally routed paths for the platform.

mpls ip (interface configuration)

tag-switching ip (interface configuration)

Enables MPLS forwarding of IPv4 packets along normally routed paths for a particular interface.

mpls ip default-route tag-switching ip default-route Enables the distribution of labels associated with the IP default route.

mpls ip propagate-ttl tag-switching ip propagate-ttl Sets the time-to-live (TTL) value when an IP packet is encapsulated in MPLS.

mpls ip ttl-expiration pop N/A Forwards packets using the global IP routing table or the original label stack, depending on the number of labels in the packet.

mpls label range tag-switching tag-range downstream

Configures the range of local labels available for use on packet interfaces.

Note The syntax of this command differs slightly from its tag-switching counterpart.

mpls mtu tag-switching mtu Sets the per-interface maximum transmission unit (MTU) for labeled packets.

show mpls forwarding-table show tag-switching forwarding-table

Displays the contents of the label forwarding information base (LFIB).

show mpls interfaces show tag-switching interfaces Displays information about one or more interfaces that have been configured for label switching.

show mpls label range N/A Displays the range of local labels available for use on packet interfaces.

Table 23 Summary of MPLS Commands Described in this Document (continued)

CommandCorresponding Tag Switching Command Description

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Multiprotocol Label Switching OverviewLabel Switching Functions


(suboptimal routing) of traffic across the service provider network. For each MPLS VPN user, the network of the service provider appears to function as a private IP backbone over which the user can reach other sites within the VPN organization, but not the sites of any other VPN organization.

From a user perspective, the MPLS VPN model enables network routing to be dramatically simplified. For example, rather than needing to manage routing over a topologically complex virtual backbone composed of many PVCs, an MPLS VPN user can generally employ the backbone of the service provider as the default route in communicating with all of the other VPN sites.

• Explicit routing capabilities (also called constraint-based routing or traffic engineering)—Explicit routing employs “constraint-based routing,” in which the path for a traffic flow is the shortest path that meets the resource requirements (constraints) of the traffic flow.

In MPLS traffic engineering, factors such as bandwidth requirements, media requirements, and the priority of one traffic flow versus another can be taken into account. These traffic engineering capabilities enable the administrator of a service provider network to perform the following tasks:

– Control traffic flow in the network

– Reduce congestion in the network

– Make best use of network resources

Thus, the network administrator can specify the amount of traffic expected to flow between various points in the network (thereby establishing a traffic matrix), while relying on the routing system to perform the following tasks:

– Calculate the best paths for network traffic

– Set up the explicit paths to carry the traffic

• Support for IP routing on ATM switches (also called IP and ATM integration)—MPLS enables an ATM switch to perform virtually all of the functions of an IP router. This capability of an ATM switch stems from the fact that the MPLS forwarding paradigm (namely, label swapping) is exactly the same as the forwarding paradigm provided by ATM switch hardware.

The key difference between a conventional ATM switch and an ATM label switch is the control software used by the latter to establish its virtual channel identifier (VCI) table entries. An ATM label switch uses IP routing protocols and the TDP to establish VCI table entries.

An ATM label switch can function as a conventional ATM switch. In this dual mode, the ATM switch resources (such as VCI space and bandwidth) are partitioned between the MPLS control plane and the ATM control plane. The MPLS control plane provides IP-based services, while the ATM control plane supports ATM-oriented functions, such as circuit emulation or PVC services.

Label Switching FunctionsIn conventional Layer 3 forwarding mechanisms, as a packet traverses the network, each router extracts all the information relevant to forwarding the packet from the Layer 3 header. This information is then used as an index for a routing table lookup to determine the next hop for the packet.

In the most common case, the only relevant field in the header is the destination address field, but in some cases other header fields might also be relevant. As a result, the header analysis must be done independently at each router through which the packet passes. A complicated table lookup must also be done at each router.

In label switching, the analysis of the Layer 3 header is done only once. The Layer 3 header is then mapped into a fixed length, unstructured value called a label.

Multiprotocol Label Switching OverviewDistribution of Label Bindings


Many different headers can map to the same label, as long as those headers always result in the same choice of next hop. In effect, a label represents a forwarding equivalence class—that is, a set of packets that, however different they may be, are indistinguishable by the forwarding function.

The initial choice of a label need not be based exclusively on the contents of the Layer 3 packet header; for example, forwarding decisions at subsequent hops can also be based on routing policy.

Once a label is assigned, a short label header is added at the front of the Layer 3 packet. This header is carried across the network as part of the packet. At subsequent hops through each MPLS router in the network, labels are swapped and forwarding decisions are made by means of MPLS forwarding table lookup for the label carried in the packet header. Hence, the packet header need not be reevaluated during packet transit through the network. Because the label is of fixed length and unstructured, the MPLS forwarding table lookup process is both straightforward and fast.

Distribution of Label BindingsEach LSR in the network makes an independent, local decision as to which label value to use to represent a forwarding equivalence class. This association is known as a label binding. Each LSR informs its neighbors of the label bindings it has made. This awareness of label bindings by neighboring routers is facilitated by the following protocols:

• TDP—Used to support MPLS forwarding along normally routed paths

• Resource Reservation Protocol (RSVP)—Used to support MPLS traffic engineering

• Border Gateway Protocol (BGP)—Used to support MPLS VPNs

When a labeled packet is being sent from LSR A to the neighboring LSR B, the label value carried by the IP packet is the label value that LSR B assigned to represent the forwarding equivalence class of the packet. Thus, the label value changes as the IP packet traverses the network.

MPLS and RoutingA label represents a forwarding equivalence class, but it does not represent a particular path through the network. In general, the path through the network continues to be chosen by the existing Layer 3 routing algorithms such as OSPF, Enhanced IGRP, and BGP. That is, at each hop when a label is looked up, the next hop chosen is determined by the dynamic routing algorithm.

MPLS Traffic EngineeringMPLS traffic engineering software enables an MPLS backbone to replicate and expand upon the traffic engineering capabilities of Layer 2 ATM and Frame Relay networks. MPLS is an integration of Layer 2 and Layer 3 technologies. By making traditional Layer 2 features available to Layer 3, MPLS enables traffic engineering. Thus, you can offer in a one-tier network what now can be achieved only by overlaying a Layer 3 network on a Layer 2 network.

Traffic engineering is essential for service provider and Internet service provider (ISP) backbones. Such backbones must support a high use of transmission capacity, and the networks must be very resilient so that they can withstand link or node failures.

MPLS traffic engineering provides an integrated approach to traffic engineering. With MPLS, traffic engineering capabilities are integrated into Layer 3, which optimizes the routing of IP traffic, given the constraints imposed by backbone capacity and topology.

Multiprotocol Label Switching OverviewMPLS Traffic Engineering


Why Use MPLS Traffic Engineering?WAN connections are an expensive item in an ISP budget. Traffic engineering enables ISPs to route network traffic to offer the best service to their users in terms of throughput and delay. By making the service provider more efficient, traffic engineering reduces the cost of the network.

Currently, some ISPs base their services on an overlay model. In the overlay model, transmission facilities are managed by Layer 2 switching. The routers see only a fully meshed virtual topology, making most destinations appear one hop away. If you use the explicit Layer 2 transit layer, you can precisely control how traffic uses available bandwidth. However, the overlay model has numerous disadvantages. MPLS traffic engineering achieves the traffic engineering benefits of the overlay model without running a separate network, and without needing a nonscalable, full mesh of router interconnects.

How MPLS Traffic Engineering WorksMPLS traffic engineering automatically establishes and maintains LSPs across the backbone by using RSVP. The path that an LSP uses is determined by the LSP resource requirements and network resources, such as bandwidth.

Available resources are flooded by means of extensions to a link-state-based Interior Gateway Protocol (IGP).

Traffic engineering tunnels are calculated at the LSP head based on a fit between required and available resources (constraint-based routing). The IGP automatically routes the traffic onto these LSPs. Typically, a packet crossing the MPLS traffic engineering backbone travels on a single LSP that connects the ingress point to the egress point.

MPLS traffic engineering is built on the following Cisco IOS mechanisms:

• IP tunnel interfaces—From a Layer 2 standpoint, an MPLS tunnel interface represents the head of an LSP. It is configured with a set of resource requirements, such as bandwidth and media requirements, and priority.

From a Layer 3 standpoint, an LSP tunnel interface is the head-end of a unidirectional virtual link to the tunnel destination.

• MPLS traffic engineering path calculation module—This calculation module operates at the LSP head. The module determines a path to use for an LSP. The path calculation uses a link-state database containing flooded topology and resource information.

• RSVP with traffic engineering extensions—RSVP operates at each LSP hop and is used to signal and maintain LSPs based on the calculated path.

• MPLS traffic engineering link management module—This module operates at each LSP hop, does link call admission on the RSVP signalling messages, and does bookkeeping of topology and resource information to be flooded.

• Link-state IGP (Intermediate System-to-Intermediate System (IS-IS) or OSPF—each with traffic engineering extensions)—These IGPs are used to globally flood topology and resource information from the link management module.

• Enhancements to the SPF calculation used by the link-state IGP (IS-IS or OSPF)—The IGP automatically routes traffic onto the appropriate LSP tunnel based on tunnel destination. Static routes can also be used to direct traffic onto LSP tunnels.

• Label switching forwarding—This forwarding mechanism provides routers with a Layer 2-like ability to direct traffic across multiple hops of the LSP established by RSVP signalling.



One approach to engineering a backbone is to define a mesh of tunnels from every ingress device to every egress device. The MPLS traffic engineering path calculation and signalling modules determine the path taken by the LSPs for these tunnels, subject to resource availability and the dynamic state of the network. The IGP, operating at an ingress device, determines which traffic should go to which egress device, and steers that traffic into the tunnel from ingress to egress.

A flow from an ingress device to an egress device might be so large that it cannot fit over a single link, so it cannot be carried by a single tunnel. In this case, multiple tunnels between a given ingress and egress can be configured, and the flow is load-shared among them.

For more information about MPLS, see the following Cisco documentation:

• Cisco IOS Switching Services Configuration Guide, “Multiprotocol Label Switching” chapter

• Cisco IOS Switching Services Command Reference, “Switching Commands Introduction” chapter

Mapping Traffic into TunnelsThis section describes how traffic is mapped into tunnels; that is, how conventional hop-by-hop link-state routing protocols interact with MPLS traffic engineering capabilities. In particular, this section describes how the shortest path first (SPF) algorithm, sometimes called a Dijkstra algorithm, has been enhanced so that a link-state IGP can automatically forward traffic over tunnels that MPLS traffic engineering establishes.

Link-state protocols, like integrated IS-IS or OSPF, use an SPF algorithm to compute a shortest path tree from the headend node to all nodes in the network. Routing tables are derived from this shortest path tree. The routing tables contain ordered sets of destination and first hop information. If a router does normal hop-by-hop routing, the first hop is over a physical interface attached to the router.

New traffic engineering algorithms calculate explicit routes to one or more nodes in the network. The originating router views these explicit routes as logical interfaces. In the context of this document, these explicit routes are represented by LSPs and referred to as traffic engineering tunnels (TE tunnels).

The following sections describe how link-state IGPs can use these shortcuts, and how they can install routes in the routing table that point to these TE tunnels. These tunnels use explicit routes, and the path taken by a TE tunnel is controlled by the router that is the headend of the tunnel. In the absence of errors, TE tunnels are guaranteed not to loop, but routers must agree on how to use the TE tunnels. Otherwise, traffic might loop through two or more tunnels.

Enhancement to the SPF Computation

During each step of the SPF computation, a router discovers the path to one node in the network, as follows:

• If that node is directly connected to the calculating router, the first hop information is derived from the adjacency database.

• If the node is not directly connected to the calculating router, the node inherits the first hop information from the parents of that node. Each node has one or more parents, and each node is the parent of zero or more downstream nodes.

For traffic engineering purposes, each router maintains a list of all TE tunnels that originate at this head end router. For each of those TE tunnels, the router at the tailend is known to the head end router.



During the SPF computation, the TENT (tentative) list stores paths that are possibly the best paths and the PATH list stores paths that are definitely the best paths. When it is determined that a path is the best possible path, the node is moved from TENT to PATH. PATH is thus the set of nodes for which the best path from the computing router has been found. Each PATH entry consists of ID, path cost, and forwarding direction.

The router must determine the first hop information using one of the following methods:

• Examine the list of tail-end routers directly reachable by a TE tunnel. If there is a TE tunnel to this node, use the TE tunnel as the first hop.

• If there is no TE tunnel and the node is directly connected, use the first hop information from the adjacency database.

• If the node is not directly connected and is not directly reachable by a TE tunnel, copy the first hop information from the parent nodes to the new node.

As a result of this computation, traffic to nodes that are the tail end of TE tunnels flows over the TE tunnels. Traffic to nodes that are downstream of the tail-end nodes also flows over the TE tunnels. If there is more than one TE tunnel to different intermediate nodes on the path to destination node X, traffic flows over the TE tunnel whose tail-end node is closest to node X.

Special Cases and Exceptions

The SPF algorithm finds equal-cost parallel paths to destinations. The enhancement previously described does not change this behavior. Traffic can be forwarded over any of the following:

• One or more native IP paths

• One or more traffic engineering tunnels

• A combination of native IP paths and traffic engineering tunnels

A special situation occurs in the topology shown in Figure 24.

Figure 24 Sample Topology of Parallel Native Paths and Paths over TE Tunnels

Router A Router B Router C

Router D Router E

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If parallel native IP paths and paths over TE tunnels are available, the following implementations allow you to force traffic to flow over TE tunnels only or only over native IP paths. Assume that all links have the same cost and that a TE tunnel is set up from Router A to Router D.

• When the SPF calculation puts Router C on the TENT list, it realizes that Router C is not directly connected. It uses the first hop information from the parent, which is Router B.

• When the SPF calculation on Router A puts Router D on the TENT list, it realizes that Router D is the tail end of a TE tunnel. Thus Router A installs a route to Router D by the TE tunnel, and not by Router B.

• When Router A puts Router E on the TENT list, it realizes that Router E is not directly connected, and that Router E is not the tail end of a TE tunnel. Therefore Router A copies the first hop information from the parents (Router C and Router D) to the first-hop information of Router E.

Traffic to Router E now load balances over the following:

• The native IP path by Router A to Router B to Router C

• The TE tunnel Router A to Router D

Additional Enhancements to SPF Computation Using Configured Tunnel Metrics

When traffic engineering tunnels install an IGP route in a Router Information Base (RIB) as next hops, the distance or metric of the route must be calculated. Normally, you could make the metric the same as the IGP metric over native IP paths as if the TE tunnels did not exist. For example, Router A can reach Router C with the shortest distance of 20. X is a route advertised in IGP by Router C. Route X is installed in the RIB of Router A with the metric of 20. When a TE tunnel from Router A to Router C comes up, by default the route is installed with a metric of 20, but the next hop information for X is changed.

Although the same metric scheme can work well in other situations, for some applications it is useful to change the TE tunnel metric (for instance, when there are equal cost paths through TE tunnel and native IP links). You can adjust TE tunnel metrics to force the traffic to prefer the TE tunnel, to prefer the native IP paths, or to load share among them.

Suppose that multiple TE tunnels go to the same destination or different destinations. TE tunnel metrics can force the traffic to prefer some TE tunnels over others, regardless of IGP distances to those destinations.

Setting metrics on TE tunnels does not affect the basic SPF algorithm. It affects only two questions:

• Is the TE tunnel installed as one of the next hops to the destination routers?

• What is the metric value of the routes being installed into the RIB?

You can modify the metrics for determining the first hop information in one of the following ways:

• If the metric of the TE tunnel to the tail end routers is higher than the metric for the other TE tunnels or native hop-by-hop IGP paths, this tunnel is not installed as the next hop.

• If the metric of the TE tunnel is equal to the metric of either other TE tunnels or native hop-by-hop IGP paths, this tunnel is added to the existing next hops.

• If the metric of the TE tunnel is lower than the metric of other TE tunnels or native hop-by-hop IGP paths, this tunnel replaces them as the only next hop.

In each of these cases, the IGP assigns metrics to routes associated with those tail end routers and their downstream routers.



The SPF computation is loop free because the traffic through the TE tunnels is basically source routed. The result of TE tunnel metric adjustment is the control of traffic load sharing. If there is only one way to reach the destination through a single TE tunnel, then no matter what metric is assigned, the traffic has only one way to go.

You can represent the TE tunnel metric in two different ways: as an absolute (or fixed) metric, or as a relative (or floating) metric.

If you use an absolute metric, the routes assigned with the metric are fixed. This metric is used not only for the routes sourced on the TE tunnel tail end router, but also for each route downstream of this tail end router that uses this TE tunnel as one of its next hops.

For example, if you have TE tunnels to two core routers in a remote point of presence (POP), and one of them has an absolute metric of 1, all traffic going to that POP traverses this low-metric TE tunnel.

If you use a relative metric, the actual assigned metric value of routes is based on the IGP metric. This relative metric can be positive or negative, and is bounded by minimum and maximum allowed metric values. For example, assume the topology shown in Figure 25.

Figure 25 Topology That Has No Traffic Engineering Tunnel

If there is no TE tunnel, Router A installs routes x, y, and z and assigns metrics 20, 30, and 40, respectively. Suppose that Router A has a TE tunnel T1 to Router C. If the relative metric –5 is used on tunnel T1, the routers x, y, and z have the installed metrics of 15, 25, and 35. If an absolute metric of 5 is used on tunnel T1, routes x, y and z have the same metric 5 installed in the RIB for Router A. The assigning of no metric on the TE tunnel is a special case, a relative metric scheme where the metric is 0.

Making the Transition from an IS-IS Network to a New TechnologyIS-IS includes extensions for MPLS traffic engineering and for other purposes. Running MPLS traffic engineering over IS-IS or taking advantage of these other extensions requires transition to an IS-IS network to this new technology. This section describes these extensions and discusses two ways to migrate an existing IS-IS network from the standard ISO 10589 protocol to IS-IS with new extensions.

Note Running MPLS traffic engineering over an existing IS-IS network requires a transition to incorporating extensions to IS-IS. However, running MPLS traffic engineering over OSPF does not require any similar network transition.

Metric = 10 Metric = 10

Subnet xMPLS TE-tunnel T1

Metric = 10 Metric = 10

Router A Router B Router C Router D Router E

Subnet y Subnet z

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New Extensions for the IS-IS Routing Protocol

New extensions for the IS-IS routing protocol serve the following purposes:

• Remove the 6-bit limit on link metrics.

• Allow interarea IP routes.

• Enable IS-IS to carry different kinds of information for traffic engineering. In the future, more extensions might be needed.

To serve these purposes, two new type, length, and value objects (TLVs) have been defined:

• TLV 22 describes links (or rather adjacencies). It serves the same purpose as the IS neighbor option in ISO 10589 (TLV 2).

• TLV 135 describes reachable IP prefixes. It is similar to the IP Neighbor options from RFC 1195 (TLVs 128 and 130).

Note For the purpose of briefness, these two new TLVs, 22 and 135, are referred to as “new-style TLVs.” TLVs 2, 128, and 130 are referred to as “old-style TLVs.”

Both new TLVs have a fixed length part, followed by optional sub-TLVs. The metric space in these new TLVs has been enhanced from 6 bits to 24 or 32 bits. The sub-TLVs allow you to add new properties to links and prefixes. Traffic engineering is the first technology to use this ability to add new properties to a link.

The Problem in Theory

Link-state routing protocols compute loop-free routes. This is guaranteed because all routers calculate their routing tables based on the same information from the link-state database.

There is a problem when some routers look at old-style TLVs and some routers look at new-style TLVs because the routers can base their SPF calculations on different information. This can cause routing loops.

The Problem in Practice

The easiest way to migrate from old-style TLVs to new-style TLVs would be to introduce a “flag day.” A flag day means that you reconfigure all routers during a short period of time, during which service is interrupted. If the implementation of a flag day is not acceptable, a network administrator needs to find a viable solution for modern existing networks.

Network administrators have the following problems related to TLVs:

• They need to run an IS-IS network where some routers are advertising and using the new-style TLVs and, at the same time, other routers are capable only of advertising and using old-style TLVs.

• They need to test new traffic engineering software in existing networks on a limited number of routers. They cannot upgrade all their routers in their production networks or in their test networks before they start testing.

The new extensions allow a network administrator to use old-style TLVs in one area, and new-style TLVs in another area. However, this is not a solution for administrators that need or want to run their network in one single area.

The following sections describe two solutions to the problem of the network administrator.



First Solution for Making the Transition from an IS-IS Network to a New Technology

When you migrate from old-style TLVs to new-style TLVs, you can advertise the same information twice—once in old-style TLVs and once in new-style TLVs. This ensures that all routers can understand what is advertised.

There are three disadvantages to using that approach:

• Size of the LSPs—During the transition, the LSPs grow to about twice their original size. This might be a problem in networks where the link-state database is large. A link-state database might be large for the following reasons:

– There are many routers, and thus LSPs.

– There are many neighbors or IP prefixes per router. A router that advertises substantial information causes the LSPs to be fragmented.

• Unpredictable results—In a large network, this solution can produce unpredictable results. A large network in transition pushes the limits regarding LSP flooding and SPF scaling. During the transition, the following behavior might occur:

– You can expect some extra network instability.

– Traffic engineering extensions might cause LSPs to be reflooded frequently.

• Ambiguity—If a router encounters different information in the old-style TLVs and the new-style TLVs, it may not be clear what the router should do.

These problems can be largely solved easily by using the following:

• All information in old-style and new-style TLVs in an LSP

• The adjacency with the lowest link metric if an adjacency is advertised more than once

The main benefit to advertising the same information twice is that network administrators can use new-style TLVs before all routers in the network can understand them.

Transition Actions During the First Solution

When making the transition from using IS-IS with old-style TLVs to new-style TLVs, you can perform the following actions:

• If all routers run old software, advertise and use only old-style TLVs.

• Upgrade some routers to newer software.

• Configure some routers with new software to advertise both old-style and new-style TLVs. They accept both styles of TLVs. Configure other routers (with old software) to continue advertising and using only old-style TLVs.

• Test traffic engineering in parts of your network; however, new-style TLVs cannot be used yet.

• If the whole network needs to migrate, upgrade and configure all remaining routers to advertise and accept both styles of TLVs.

• Configure all routers to advertise and accept only new-style TLVs.

• Configure metrics larger than 63.

For more information about how to perform these actions, see the section “TLV Configuration Commands.”



Second Solution for Making the Transition from an IS-IS Network to a New Technology

Routers advertise only one style of TLVs at the same time, but can understand both types of TLVs during migration. There are two main benefits to this approach:

• LSPs stay approximately the same size during migration.

• There is no ambiguity when the same information is advertised twice inside one LSP.

This method is useful when you move the whole network (or a whole area) to use wider metrics (that is, you want a router running IS-IS to generate and accept only new-style TLVs). For more information, see the metric-style wide router configuration command.

The disadvantage is that all routers must understand the new-style TLVs before any router can start advertising new-style TLVs. It does not help the second problem, where network administrators want to use the new-style TLVs for traffic engineering, while some routers are capable of understanding only old-style TLVs.

Transition Actions During the Second Solution

If you use the second solution, you can perform the following actions:

• If all routers run old software, advertise and use only old-style TLVs.

• Upgrade all routers to newer software.

• Configure all routers one-by-one to advertise old-style TLVs, but to accept both styles of TLVs.

• Configure all routers one-by-one to advertise new-style TLVs, but to accept both styles of TLVs.

• Configure all routers one-by-one to advertise and to accept only new-style TLVs.

• Configure metrics larger than 63.

TLV Configuration CommandsCisco IOS software has a new router isis CLI command called metric-style. Once you are in the router IS-IS command mode, you have the option to choose the following:

• Metric-style narrow—Enables the router to generate and accept only old-style TLVs

• Metric-style transition—Enables the router to generate and accept both old-style and new-style TLVs

• Metric-style wide—Enables the router to generate and accept only new-style TLVs

You can use either of two transition schemes when you are using the metric-style commands:

• Narrow to transition to wide

• Narrow to narrow transition to wide transition to wide

Implementation in Cisco IOS SoftwareCisco IOS software implements both transition solutions of moving your IS-IS network to a new technology. Network administrators can choose the solution that suits them. For test networks, the first solution is ideal (see the section “First Solution for Making the Transition from an IS-IS Network to a New Technology”). For a real transition, both solutions can be used. The first solution requires fewer

Multiprotocol Label Switching OverviewMPLS Virtual Private Networks


steps and less configuration. Only the largest networks that do not want to double their link-state database during transition need to use the second solution (see the “Second Solution for Making the Transition from an IS-IS Network to a New Technology”).

MPLS Virtual Private NetworksUsing MPLS VPNs in a Cisco IOS network provide the capability to deploy and administer scalable Layer 3 VPN backbone services including applications, data hosting network commerce, and telephony services to business customers. A VPN is a secure IP-based network that shares resources on one or more physical networks. A VPN contains geographically dispersed sites that can communicate securely over a shared backbone.

A one-to-one relationship does not necessarily exist between customer sites and VPNs; a given site can be a member of multiple VPNs. However, a site can associate with only one VPN routing and forwarding instance (VRF). Each VPN is associated with one or more VPN VRFs. A VRF includes routing and forwarding tables and rules that define the VPN membership of customer devices attached to CE routers. A VRF consists of the following:

• IP routing table

• CEF table

• Set of interfaces that use the CEF forwarding table

• Set of rules and routing protocol parameters to control the information in the routing tables

VPN routing information is stored in the IP routing table and the CEF table for each VRF. A separate set of routing and CEF tables is maintained for each VRF. These tables prevent information from being forwarded outside a VPN and also prevent packets that are outside a VPN from being forwarded to a router within the VPN.

The following sections provide more information on MPLS VPNs:

• Benefits

• VPN Operation

• Distribution of VPN Routing Information

• BGP Distribution of VPN Routing Information

• MPLS Forwarding

• MPLS VPN Cable Interfaces

• Interautonomous Systems for MPLS VPNs

• HSRP Support for MPLS VPNS

BenefitsMPLS VPNs allow service providers to deploy scalable VPNs and build the foundation to deliver value-added services, including the following:

• Connectionless service—A significant technical advantage of MPLS VPNs is that they are connectionless. The Internet owes its success to its basic technology, TCP/IP. TCP/IP is built on packet-based, connectionless network paradigm. This means that no prior action is necessary to establish communication between hosts, making it easy for two parties to communicate. To establish privacy in a connectionless IP environment, current VPN solutions impose a connection-oriented,



point-to-point overlay on the network. Even if it runs over a connectionless network, a VPN cannot take advantage of the ease of connectivity and multiple services available in connectionless networks. When you create a connectionless VPN, you do not need tunnels and encryption for network privacy, thus eliminating substantial complexity.

• Centralized service—Building VPNs in Layer 3 allows delivery of targeted services to a group of users represented by a VPN. A VPN must give service providers more than a mechanism for privately connecting users to intranet services. It must also provide a way to flexibly deliver value-added services to targeted customers. Scalability is critical, because customers want to use services privately in their intranets and extranets. Because MPLS VPNs are seen as private intranets, you may use IP services such as the following:

– Multicast

– Quality of service (QoS)

– Telephony support within a VPN

– Centralized services including content and web hosting to a VPN

You can customize several combinations of specialized services for individual customers. For example, a service that combines IP multicast with a low-latency service class enables videoconferencing within an intranet.

• Scalability—If you create a VPN using connection-oriented, point-to-point overlays, Frame Relay, or ATM virtual connections, the VPN’s key deficiency of the VPN is scalability. Specifically, connection-oriented VPNs without fully meshed connections between customer sites are not optimal. MPLS-based VPNs instead use the peer model and Layer 3 connectionless architecture to leverage a highly scalable VPN solution. The peer model requires a customer site to only peer with one provider edge (PE) router as opposed to all other CPE or CE routers that are members of the VPN. The connectionless architecture allows the creation of VPNs in Layer 3, eliminating the need for tunnels or virtual connections.

The following are scalability issues of MPLS VPNs due to the partitioning of VPN routes between PE routers and the further partitioning of VPN and IGP routes between PE routers and provider (P) routers in a core network:

– PE routers must maintain VPN routes for those VPNs that are members.

– P routers do not maintain any VPN routes.

This increases the scalability of the provider’s core and ensures that no one device is a scalability bottleneck.

• Security—MPLS VPNs offer the same level of security as connection-oriented VPNs. Packets from one VPN do not inadvertently go to another VPN. Security is provided

– At the edge of a provider network, ensuring that packets received from a customer are placed on the correct VPN.

– At the backbone, ensuring that VPN traffic is kept separate. Malicious spoofing (an attempt to gain access to a PE router) is nearly impossible because the packets received from customers are IP packets. These IP packets must be received on a particular interface or subinterface to be uniquely identified with a VPN label.

• Easy to create—To take full advantage of VPNs, it must be easy for you to create new VPNs and user communities. Because MPLS VPNs are connectionless, no specific point-to-point connection maps or topologies are required. You can add sites to intranets and extranets and form closed user groups. When you manage VPNs in this manner, it enables membership of any given site in multiple VPNs, maximizing flexibility in building intranets and extranets.



• Flexible addressing—To make a VPN service more accessible, customers of a service provider can design their own addressing plan, independent of addressing plans for other service provider customers. Many customers use private address spaces and do not want to invest the time and expense of converting to public IP addresses to enable intranet connectivity. MPLS VPNs allow customers to continue to use their present address spaces without Network Address Translation (NAT) by providing a public and private view of the address. A NAT is required only if two VPNs with overlapping address spaces want to communicate. This enables customers to use their own unregistered private addresses, and to communicate freely across a public IP network.

• Integrated Quality of Service (QoS) support—QoS is an important requirement for many IP VPN customers. It provides the ability to address two fundamental VPN requirements:

– Predictable performance and policy implementation

– Support for multiple levels of service in an MPLS VPN

Network traffic is classified and labeled at the edge of the network before traffic is aggregated according to policies defined by subscribers and implemented by the provider and transported across the provider core. Traffic at the edge and core of the network can then be differentiated into different classes by drop probability or delay.

• Straightforward migration—For service providers to quickly deploy VPN services, use a straightforward migration path. MPLS VPNs are unique because you can build them over multiple network architectures, including IP, ATM, Frame Relay, and hybrid networks.

Migration for the end customer is simplified because there is no requirement to support MPLS on the CE router and no modifications are required to a intranet belonging to a customer.

Figure 26 shows an example of a VPN with a service provider (P) backbone network, service provider edge routers (PE), and customer edge routers (CE).

Figure 26 VPNs with a Service Provider Backbone

A VPN contains customer devices attached to the CE routers. These customer devices use VPNs to exchange information between devices. Only the PE routers are aware of the VPNs.

CE

PE

PE

CE

PE CE

CE

P

Service providerbackbone

VPN 1

VPN 1

VPN 2

Site 1 Site 1

Site 2

Site 2

P

P

P

1726

5



Figure 27 shows five customer sites communicating within three VPNs. The VPNs can communicate with the following sites:

• VPN1—Sites 2 and 4

• VPN2—Sites 1, 3, and 4

• VPN3—Sites 1,3, and 5

Figure 27 Customer Sites within VPNs

Increased BGP Functionality

The following is a list of increased BGP functionality:

• Configuring BGP hub and spoke connections—Configuring PE routers in a hub and spoke configuration allows a CE router to readvertise all prefixes containing duplicate autonomous system numbers (ASNs) to neighboring PE routers. Using duplicate ASNs in a hub and spoke configuration provides faster convergence of routing information within geographically dispersed locations.

• Configuring faster convergence for BGP VRF routes—Configuring scanning intervals of BGP routers decreases import processing time of VPNv4 routing information, thereby providing faster convergence of routing information. Routing tables are updated with routing information about VPNv4 routes learned from PE routers or route reflectors.

• Limiting VPN VRFs—Limiting the number of routes in a VRF prevents a PE router from importing too many routes, thus diminishing the performance of a router. This enhancement can also be used to enforce the maximum number of members that can join a VPN from a particular site. A threshold is set in the VRF routing table to limit the number of VRF routes imported.

• Reusing ASNs in an MPLS VPN environment—Configuring a PE router to reuse an existing ASN allows customers to configure BGP routes with the same ASNs in multiple geographically dispersed sites, providing better scalability between sites.

• Distributing BGP OSPF routing information—Setting a separate router ID for each interface or subinterface on a PE router attached to multiple CE routers within a VPN provides increased flexibility through OSPF when routers exchange routing information between sites.

Table 24 lists the MPLS VPN features and the associated BGP commands.

Site 2

VPN1VPN2

VPN3

Site 4

Site 5

1726

6

Site 3

Site 1



VPN OperationEach VPN is associated with one or more VRFs. A VRF defines the VPN membership of a customer site attached to a PE router. A VRF consists of an IP routing table, a derived CEF table, a set of interfaces that use the forwarding table, and a set of rules and routing protocol parameters that control the information that is included into the routing table.

A one-to-one relationship does not necessarily exist between customer sites and VPNs. A given site can be a member of multiple VPNs, as shown in Figure 27. However, a site can only associate with one (and only one) VRF. A customer’s site VRF contains all the routes available to the site from the VPNs of which it is a member.

Packet forwarding information is stored in the IP routing table and the CEF table for each VRF. A separate set of routing and CEF tables is maintained for each VRF. These tables prevent information from being forwarded outside a VPN, and also prevent packets that are outside a VPN from being forwarded to a router within the VPN.

Table 24 MPLS VPN Features and the Associated BGP Commands

Name of Cisco IOS Feature Command Description

Configuring Faster Convergence for BGP VRF Routes

bgp scan-time import Configures scanning intervals of BGP routers to decrease import processing time of routing information.

Limiting VRF Routes maximum routes Limits the number of routes in a VRF to prevent a PE router from importing too many routes.

Configuring BGP Hub and Spoke Connections

neighbor allowas-in Configures PE routers to allow CE routers to readvertise all prefixes that contain duplicate ASNs to neighboring PE routers.

Reusing ASNs in an MPLS VPN Environment

neighbor as-override Configures a PE router to reuse the same ASN on all sites within an MPLS VPN by overriding private ASNs.

Distributing BGP OSPF Routing Information

set ospf router-id Sets a separate router ID for each interface or subinterface on the PE router for each directly attached CE router.



Distribution of VPN Routing InformationThe distribution of VPN routing information is controlled through the use of VPN route target communities, implemented by BGP extended communities. Distribution of VPN routing information works as follows:

• When a VPN route learned from a CE router is injected into BGP, a list of VPN route target extended community attributes is associated with it. Typically the list of route target community extended values is set from an export list of route targets associated with the VRF from which the route was learned.

• An import list of route target extended communities is associated with each VRF. The import list defines route target extended community attributes that a route must have in order for the route to be imported into the VRF. For example, if the import list for a particular VRF includes route target extended communities A, B, and C, then any VPN route that carries any of those route target extended communities—A, B, or C—is imported into the VRF.

BGP Distribution of VPN Routing InformationA PE router can learn an IP prefix from a CE router by static configuration, through a BGP session with the CE router, or through the Routing Information Protocol (RIP) exchange with the CE router. The IP prefix is a member of the IPv4 address family. After it learns the IP prefix, the PE converts it into a VPN-IPv4 prefix by combining it with an 8-byte route distinguisher (RD). The generated prefix is a member of the VPN-IPv4 address family. It uniquely identifies the customer address, even if the customer site is using globally nonunique (unregistered private) IP addresses.

The RD used to generate the VPN-IPv4 prefix is specified by a configuration command associated with the VRF on the PE router.

BGP distributes reachability information for VPN-IPv4 prefixes for each VPN. BGP communication takes place at two levels: within IP domains, known as autonomous systems (Interior BGP or IBGP) and between autonomous systems (Exterior BGP or EBGP). PE-PE or PE-RR (route reflector) sessions are IBGP sessions, and PE-CE sessions are EBGP sessions.

BGP propagates reachability information for VPN-IPv4 prefixes among PE routers by means of the BGP multiprotocol extensions, which define support for address families other than IPv4. It does this in a way that ensures that the routes for a given VPN are learned only by other members of that VPN, enabling members of the VPN to communicate.

MPLS Forwarding Based on routing information stored in the VRF IP routing table and VRF CEF table, packets are forwarded to their destination using MPLS.

A PE router binds a label to each customer prefix learned from a CE router and includes the label in the network-layer reachability information (NLRI) for the prefix that it advertises to other PE routers. When a PE router forwards a packet received from a CE router across the provider network, it labels the packet with the label learned from the destination PE router. When the destination PE router receives the labeled packet, it pops the label and uses it to direct the packet to the correct CE router. Label forwarding across the provider backbone, is based on either dynamic label switching or traffic engineered paths. A customer data packet carries two levels of labels when traversing the backbone:

• The top label directs the packet to the correct PE router.

• The second label indicates how that PE router should forward the packet to the CE router.



MPLS VPN Cable InterfacesUsing MPLS VPN technology, service providers can create scalable and efficient private networks using a shared hybrid fiber coaxial (HFC) network and IP infrastructure.

The cable MPLS VPN network consists of the following:

• The multiple service operator (MSO) or cable company that owns the physical infrastructure and builds VPNs for the ISPs to move traffic over the cable and IP backbone.

• ISPs that use the HFC network and IP infrastructure to supply Internet service to cable customers.

Each ISP moves traffic to and from the PC of a subscriber, through the physical network infrastructure of the MSO, to the network of the ISP. MPLS VPNs, created in Layer 3, provide privacy and security by constraining the distribution of the routes of a VPN only to the routers that belong to its network. Thus, each VPN of the ISP is insulated from other ISPs that use the same MSO infrastructure.

An MPLS VPN assigns a unique VRF instance to each VPN. A VRF instance consists of an IP routing table, a derived forwarding table, a set of interfaces that use the forwarding table, and a set of rules and routing protocols that determine the contents of the forwarding table.

Each PE router maintains one or more VRF tables. It looks up a IP destination address of a packet in the appropriate VRF table, only if the packet arrived directly through an interface associated with that table.

MPLS VPNs use a combination of BGP and IP address resolution to ensure security. Refer to the “Configuring Multiprotocol Label Switching” chapter later in this publication.

Figure 28 shows a cable MPLS VPN network. The routers in the network are as follows:

• Provider (P) router—Routers in the core of the provider network. P routers run MPLS switching, and do not attach VPN labels (MPLS label in each route assigned by the PE router) to routed packets. VPN labels are used to direct data packets to the correct egress router.

• PE router—Router that attaches the VPN label to incoming packets based on the interface or subinterface on which they are received. A PE router attaches directly to a CE router. In the MPLS VPN approach, each Cisco uBR7200 series router acts as a PE router.

• Customer (C) router—Router in the ISP or enterprise network.

• Customer Edge (CE) router—Edge router on the network of the ISP that connects to the PE router on the network of the MSO. A CE router must interface with a PE router.

The MPLS network has a unique VPN that exclusively manages the MSOs devices called the management VPN. It contains servers and devices that other VPNs can access. The management VPN connects the Cisco uBR7200 series router to a PE router, which connects to management servers such as Cisco Network Registrar (CNR) and Time of Day (ToD) servers. A PE router connects to management servers and is a part of the management VPN. Regardless of the ISP they belong to, the management servers serve the Dynamic Host Configuration Protocol (DHCP), DNS (Domain Name System), and ToD requests coming from PCs or cable modems.



Figure 28 MPLS VPN Network

Cable VPN configuration involves the following:

• MSO domain that requires a direct peering link to each enterprise network (ISP), provisioning servers for residential and commercial subscribers, and dynamic DNS for commercial users. The MSO manages cable interface IP addressing, Data-over-Cable Service Interface Specifications (DOCSIS) provisioning, CM host names, routing modifications, privilege levels, and usernames and passwords.

• ISP or enterprise domain that includes the DHCP server for subscriber or telecommuter host devices, enterprise gateway within the MSO address space, and static routes back to the telecommuter subnets.

Note We recommend that the MSO assign all addresses to the end-user devices and gateway interfaces. The MSO can also use split management to let the ISP configure tunnels and security.

In an MPLS VPN configuration, the MSO must configure the following:

• CMTS (Cisco uBR7200 series routers)

• P routers

• PE routers

• CE routers

• One VPN per ISP DOCSIS server for all cable modem customers. The MSO must attach DOCSIS servers to the management VPN, and make them visible.

The MSO must configure Cisco uBR7200 series routers that serve the ISP, and remote PE routers connecting to the ISP, as PE routers in the VPN.

CE

CE

ISP-AVPN

ISP-Acustomer

ISP-BcustomerISP-B

VPNPE

PE

MSO

PE

Management router

3563

8

HFC cable network

VPN

MGMT

VPN B

VP

N A

Providercore

Management subnet

Cisco uBR 7246



The MSO must determine the primary IP address range, which is the range of the MSO for all cable modems belonging to the ISP subscribers.

The ISP must determine the secondary IP address range, which is the range of the ISP for its subscriber PCs.

To reduce security breaches and differentiate DHCP requests from cable modems in VPNs or under specific ISP management, MSOs can use the cable helper-address cable interface command in Cisco IOS software. The MSO can specify the host IP address to be accessible only in the VPN of the ISP. This lets the ISP use its DHCP server to allocate IP addresses. Cable modem IP addresses must be accessible from the management VPN.

The MPLS VPN approach of creating VPNs for individual ISPs or customers requires subinterfaces to be configured on the cable interface or the cable interface bundle. Each ISP requires one subinterface. The subinterfaces are tied to the VRF tables for their respective ISPs. The first subinterface must be created on the cable interface bound to the management VPN.

To route a reply from the CNR back to the cable modem, the PE router that connects to the CNR must import the routes of the ISP VPN into the management VPN. Similarly, to forward management requests (such as DHCP renewal to CNR) to the cable modems, the ISP VPN must export and import the appropriate management VPN routes.

Cisco uBR7200 series software supports the definition of logical network-layer interfaces over a physical cable interface or a bundle of cable interfaces. You can create subinterfaces on either a physical cable interface or a bundle of cable interfaces. Subinterfaces let service providers share one IP subnet across multiple cable interfaces grouped into a cable interface bundle.

You can group all of the cable interfaces on a Cisco uBR7200 series router into a single bundle so that only one subnet is required for each router. When you group cable interfaces, no separate IP subnet or each individual cable interface is required. This grouping avoids performance, memory, and security problems in using a bridging solution to manage subnets, especially for a large number of subscribers.

Subinterfaces allow traffic to be differentiated on a single physical interface, and assigned to multiple VPNs. You can configure multiple subinterfaces, and associate an MPLS VPN with each subinterface. You can split a single physical interface (the cable plant) into multiple subinterfaces, where each subinterface is associated with a specific VPN. Each ISP requires access on a physical interface and is given its own subinterface. Create a management subinterface to support cable modem initialization from an ISP.

Using each subinterface associated with a specific VPN (and therefore, ISP), subscribers connect to a logical subinterface, which reflects the ISP that provides their subscribed services. When properly configured, subscriber traffic enters the appropriate subinterface and VPN.

The CMTS MSO administrator can define subinterfaces on a cable physical interface and assign Layer 3 configurations to each subinterface, or bundle a group of physical interfaces, define subinterfaces on the bundle master, and give each subinterface a Layer 3 configuration.

Benefits

MPLS VPNs with cable interfaces provide the following benefits:

• MPLS VPNs give cable MSOs and ISPs a manageable way of supporting multiple access to a cable plant. Service providers can create scalable and efficient VPNs across the core of their networks. MPLS VPNs provide systems support scalability in cable transport infrastructure and management.

• Each ISP can support Internet access services from a PC of a subscriber through a physical cable plant of a MSO to their networks.



• MPLS VPNs allow MSOs to deliver value-added services through an ISP, and thus, deliver connectivity to a wider set of potential customers. MSOs can partner with ISPs to deliver multiple services from multiple ISPs and add value within the own network of a MSO using VPN technology.

• Subscribers can select combinations of services from various service providers.

• The Cisco IOS MPLS VPN cable feature sets build on CMTS DOCSIS 1.0 and DOCSIS 1.0 extensions to ensure that services are reliably and optimally delivered over the cable plant. MPLS VPN provides systems support domain selection, authentication per subscriber, selection of Quality of Service (QoS), policy-based routing (PBR), and the ability to reach behind the cable modem to subscriber end devices for QoS and billing while preventing session spoofing.

• MPLS VPN technology ensures both secure access across the shared cable infrastructure and service integrity.

• Cable interface bundling eliminates the need for an IP subnet on each cable interface. Instead, an IP subnet is only required for each cable interface bundle. All cable interfaces in a Cisco uBR7200 series router can be added to a single bundle.

Interautonomous Systems for MPLS VPNsThe interautonomous system for MPLS VPNs feature allows an MPLS VPN to span service providers and autonomous systems.

As VPNs grow, their requirements expand. In some cases, VPNs need to reside on different autonomous systems in different geographic areas. (An autonomous system is a single network or group of networks that is controlled by a common system administration group and that uses a single, clearly defined routing protocol.) Also, some VPNs need to extend across multiple service providers (overlapping VPNs). Regardless of the complexity and location of the VPNs, the connection between autonomous systems must be seamless to the customer.

The interautonomous systems for MPLS VPNs feature provides seamless integration of autonomous systems and service providers. Separate autonomous systems from different service providers can communicate by exchanging IPv4 network layer reachability information (NLRI) in the form of VPN-IPv4 addresses. The border edge routers of autonomous systems use the EBGP to exchange that information. Then, an IGP distributes the network layer information for VPN-IPv4 prefixes throughout each VPN and each autonomous system. Routing information uses the following protocols:

• Within an autonomous system, routing information is shared using an IGP.

• Between autonomous systems, routing information is shared using an EBGP. An EBGP allows a service provider to set up an interdomain routing system that guarantees the loop-free exchange of routing information between separate autonomous systems.

An MPLS VPN with interautonomous system support allows a service provider to provide to customers scalable Layer 3 VPN services, such as web hosting, application hosting, interactive learning, electronic commerce, and telephony service. A VPN service provider supplies a secure, IP-based network that shares resources on one or more physical networks.

The primary function of an EBGP is to exchange network reachability information between autonomous systems, including information about the list of autonomous system routes. The autonomous systems use EGBP border edge routers to distribute the routes, which include label switching information. Each border edge router rewrites the next hop and MPLS labels.



Interautonomous system configurations supported in an MPLS VPN can include the following:

• Interprovider VPN—MPLS VPNs that include two or more autonomous systems, connected by separate border edge routers. The autonomous systems exchange routes using EBGP. No IGP or routing information is exchanged between the autonomous systems.

• BGP confederations—MPLS VPNs that divide a single autonomous system into multiple subautonomous systems, and classify them as a single, designated confederation. The network recognizes the confederation as a single autonomous system. The peers in the different autonomous systems communicate over EBGP sessions; however, they can exchange route information as if they were IBGP peers.

Benefits of interautonomous Systems for MPLS VPNs are as follows:

• Allows a VPN to cross more than one service provider backbone—The interautonomous systems for MPLS VPNs feature allows service providers, running separate autonomous systems, to jointly offer MPLS VPN services to the same end customer. A VPN can begin at one customer site and traverse different VPN service provider backbones before arriving at another site of the same customer. Previous MPLS VPNs could only traverse a single BGP autonomous system service provider backbone. The interautonomous system feature allows multiple autonomous systems to form a continuous (and seamless) network between customer sites of a service provider.

• Allows a VPN to exist in different areas—The interautonomous systems for MPLS VPNs feature allows a service provider to create a VPN in different geographic areas. Having all VPN traffic flow through one point (between the areas) allows for better rate control of network traffic between the areas.

• Allows confederations to optimize IBGP meshing—The interautonomous systems for MPLS VPNs feature can make IBGP meshing in an autonomous system more organized and manageable. You can divide an autonomous system into multiple, separate subautonomous systems and then classify them into a single confederation (even though the entire VPN backbone appears as a single autonomous system). This capability allows a service provider to offer MPLS VPNs across the confederation because it supports the exchange of labeled VPN-IPv4 NLRI between the subautonomous systems that form the confederation.

Routing Between Autonomous Systems

Figure 29 illustrates one MPLS VPN consisting of two separate autonomous systems. Each autonomous system operates under different administrative control and runs a different IGP. Service providers exchange routing information through EBGP border edge routers (ASBR1 and ASBR2).



Figure 29 EBGP Connection Between Two Autonomous Systems

This configuration uses the following process to transmit information:

Step 1 The provider edge router (PE-1) assigns a label for a route before distributing that route. The PE router uses the multiprotocol extensions of a BGP to send label mapping information. The PE router distributes the route as an VPN-IPv4 address. The address label and the VPN identifier are encoded as part of the NLRI.

Step 2 The two route reflectors (RR-1 and RR-2) reflect VPN-IPv4 internal routes within the autonomous system. The border edge routers of autonomous systems (ASBR1 and ASBR2) advertise the VPN-IPv4 external routes.

Step 3 The EBGP border edge router (ASBR1) redistributes the route to the next autonomous system (ASBR2). ASBR1 specifies its own address as the value of the EBGP next hop attribute and assigns a new label. The address ensures the following:

• That the next hop router is always reachable in the service provider (P) backbone network.

• That the label assigned by the distributing router is properly interpreted. (The label associated with a route must be assigned by the corresponding next hop router.)

Step 4 The EBGP border edge router (ASBR2) redistributes the route in one of the following ways, depending on its configuration:

• If the IBGP neighbors are configured with the neighbor next-hop-self router configuration command, ASBR2 changes the next hop address of updates received from the EBGP peer, then forwards it.

• If the IBGP neighbors are not configured with the neighbor next-hop-self router configuration command, the next hop address does not get changed. ASBR2 must propagate a host route for the EBGP peer through the IGP. To propagate the EBGP VPN-IPv4 neighbor host route, use the redistribute connected subnets command. The EBGP VPN-IPv4 neighbor host route is automatically installed in the routing table when the neighbor comes up. This is essential to establish the label-switched path between PE routers in different autonomous systems.

CE-1 CE-2

CE-3 CE-4

CE-5

PE-1 PE-2 PE-3

RR-1 RR-2

ASBR1 ASBR2

Core of Prouters

Service Provider 1 Service Provider 2

EBGP VPNv4routes with label

distribution

4387

7

Core of Prouters

VPN1

VPN1



Exchanging VPN Routing Information

Autonomous systems exchange VPN routing information (routes and labels) to establish connections. To control connections between autonomous systems, the PE routers and EBGP border edge routers maintain an LFIB. The LFIB manages the labels and routes that the PE routers and EBGP border edge routers receive during the exchange of VPN information.

Figure 30 illustrates the exchange of VPN route and label information between autonomous systems. The autonomous systems use the following guidelines to exchange VPN routing information:

• Routing information includes:

– The destination network (N)

– The next hop field associated with the distributing router

– A local MPLS label (L)

• An RD1: route distinguisher (the route target value) is part of a destination network address to make the VPN-IPv4 route globally unique in the VPN service provider environment.

• When a router redistributes the route, it reassigns the label value and sets the next hop field to the address of the distributing router (next-hop-self). Each VPN-IPv4 NRLI includes an MPLS label. When a router changes the next hop field for a route, it changes the label field to a value that is significant to the next hop destination router.

Figure 30 Exchanging Routes and Labels Between Autonomous Systems in an Interprovider VPN

Network

Figure 31 illustrates the exchange of VPN route and label information between autonomous systems. The difference between Figure 30 and Figure 31 is that ASBR2 is configured with the redistribute connected router configuration command, which propagates the host routes to all PEs. The redistribute connected router configuration command is necessary because ASBR2 is not configured to change the next hop address.

PE-3

CE-1 CE-2 CE-3 CE-4 CE-5

PE-1 PE-2

RR-1 RR-2

ASBR1 ASBR2

Core of P routers

Core of Prouters

Network = RD1:N Next hop = PE-1Label = L1

Network = RD1:N Next hop = ASBR2 Label = L3

Network = RD1:N Next hop = PE-1 Label = L1

Network = RD1:N Next hop = ASBR2

Label = L3

Network = RD1:NNext hop = ASBR1

Label = L2Network = N Next hop = CE-2 Network = N

Next hop = PE-3

43

87

8


VPN1 VPN1



Figure 31 Exchanging Routes and Labels Between Autonomous Systems in an Interprovider VPN

Network

Packet Forwarding

Figure 32 illustrates how packets are forwarded between autonomous systems in an interprovider network using the following packet forwarding method.

Packets are forwarded to their destination by means of MPLS. Packets use the routing information stored in the LFIB of each PE router and EBGP border edge router.

The service provider VPN backbone uses dynamic label switching to forward labels.

Each autonomous system uses standard multilevel labeling to forward packets between the edges of the autonomous system routers (for example, from CE-5 to PE-3). Between autonomous systems, only a single level of labeling is used, corresponding to the advertised route.

A data packet carries two levels of labels when traversing the VPN backbone:

• The first label (IGP route label) directs the packet to the correct PE router or EBGP border edge router. (For example, the IGP label of ASBR2 points to the ASBR2 border edge router.)

• The second label (VPN route label) directs the packet to the appropriate PE router or EBGP border edge router.

PE-3

CE-1 CE-2

CE-3 CE-4

CE-5

PE-1 PE-2

RR-1 RR-2

ASBR1 ASBR2

Core of P routers

Core of Prouters

Network = RD1:N Next hop = PE-1Label = L1

Network = RD1:NNext hop = ASBR1 Label = L2

Network = RD1:N Next hop = PE-1 Label = L1

Network = RD1:N Next hop = ASBR1

Label = L2

Network = RD1:NNext hop = ASBR1

Label = L2

Network = N Next hop = CE-2 Network = N

Next hop = PE-3

4829

9


VPN1

VPN1



Figure 32 Forwarding Packets Between Autonomous Systems in an Interprovider VPN Network

Figure 33 illustrates the same packet forwarding method, except the EBGP router (ASBR1) forwards the packet without reassigning it a new label.

Figure 33 Forwarding Packets Between Autonomous Systems in an Interprovider VPN Network

CE-1 CE-2

CE-3 CE-4

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Network = NVPN label = L1 Network = RD1:N

VPN label = L2

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Network = NIGP label = ASBR2

VPN label = L3

VPN 1

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Service Provider 2

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Network = NVPN label = L1 Network = RD1:N

VPN label = L2

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VPN label = L2

Network = NNetwork = N

Network = RD1:NIGP label = PE1VPN label = L1

Network = NIGP label = ASBR1

VPN label = L2

VPN 1

VPN 1

Service Provider 1

Service Provider 2



Routing Between Subautonomous Systems in a Confederation

A VPN can span service providers running in separate autonomous systems or between multiple subautonomous systems that have been grouped together to form a confederation.

A confederation reduces the total number of peer devices in an autonomous system. A confederation divides an autonomous system into subautonomous systems and assigns a confederation identifier to the autonomous systems.

In a confederation, each subautonomous system is fully meshed with other subautonomous systems. The subautonomous systems communicate using an IGP, such as OSPF or IS-IS. Each subautonomous system also has an EBGP connection to the other subautonomous systems. The confederation EBGP (CEBGP) border edge routers forward next-hop-self addresses between the specified subautonomous systems. The next-hop-self address forces the BGP to use a specified address as the next hop rather than letting the protocol choose the next hop.

You can configure a confederation with separate subautonomous systems in two ways:

• You can configure a router to forward next-hop-self addresses between only the CEBGP border edge routers (both directions). The subautonomous systems (IBGP peers) at the subautonomous system border do not forward the next-hop-self address. Each subautonomous system runs as a single IGP domain. However, the CEBGP border edge router addresses are known in the IGP domains.

• You can configure a router to forward next-hop-self addresses between the CEBGP border edge routers (both directions) and within the IBGP peers at the subautonomous system border. Each subautonomous system runs as a single IGP domain but also forwards next-hop-self addresses between the PE routers in the domain. The CEBGP border edge router addresses are known in the IGP domains.

Note Figure 30 and Figure 31 illustrate how two autonomous systems exchange routes and forward packets. Subautonomous systems in a confederation use a similar method of exchanging routes and forwarding packets.

Figure 34 illustrates a typical MPLS VPN confederation configuration. The following behavior occurs in this confederation configuration:

• The two CEBGP border edge routers exchange VPN-IPv4 addresses with labels between the two subautonomous systems.

• The distributing router changes the next hop addresses and labels and uses a next-hop-self address.

• IGP-1 and IGP-2 know the addresses of CEBGP-1 and CEBGP-2.

Multiprotocol Label Switching OverviewMPLS Quality of Service


Figure 34 EBGP Connection Between Two Subautonomous Systems in a Confederation

The following behavior occurs in this confederation configuration:

• CEBGP border edge routers function as neighboring peers between the subautonomous systems. The subautonomous systems use EBGP to exchange route information.

• Each CEBGP border edge router (CEBGP-1 and CEBGP-2) assigns a label for the route before distributing the route to the next subautonomous system. The CEBGP border edge router distributes the route as an VPN-IPv4 address by using the multiprotocol extensions of BGP. The label and the VPN identifier are encoded as part of the NLRI.

• Each PE and CEBGP border edge router assigns its own label to each VPN-IPv4 address prefix before redistributing the routes. The CEBGP border edge routers exchange VPN-IPv4 addresses with the labels. The next-hop-self address is included in the label (as the value of the EBGP next hop attribute). Within the subautonomous systems, the CEBGP border edge router address is distributed throughout the IBGP neighbors and the two CEBGP border edge routers are known to both confederations.

HSRP Support for MPLS VPNSHot Standby Router Protocol (HSRP) can now provide transparent “first-hop IP routing” redundancy for workstations or routers connected to interfaces within MPLS VPNs. For more information on enabling HSRP or configuring HSRP group attributes, refer to the “Configuring IP Services” chapter in the Cisco IOS IP Configuration Guide.

MPLS Quality of ServiceThe quality of service (QoS) feature for MPLS enables network administrators to provide differentiated types of service across an MPLS network. Differentiated service satisfies a range of requirements by supplying for each packet transmitted the particular kind of service specified for that packet by its QoS. Service can be specified in different ways, for example, using the IP precedence bit settings in IP packets.

CE-1 CE-2

CE-3 CE-4

CE-5

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CEGBP-1 CEBGP-2

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eBGP intraconfederationfor VPNv4 routes with labeldistribution


VPN 1

VPN 1



In supplying differentiated service, MPLS QoS offers packet classification, congestion avoidance, and congestion management. Table 25 lists these functions and their descriptions.

Note MPLS QoS lets you duplicate Cisco IOS IP QoS (Layer 3) features as closely as possible in MPLS devices, including label edge routers (LERs), LSRs, and ATM-LSRs. MPLS QoS functions map nearly one-for-one to IP QoS functions on all interface types.

For more information on configuration of the QoS functions (CAR, WRED, and CBWFQ), refer to the Cisco IOS Quality of Service Solutions Configuration Guide.

For complete command syntax information for CAR, WRED, and WFQ, refer to the Cisco IOS Quality of Service Solutions Command Reference.

Specifying the QoS in the IP Precedence FieldWhen you send IP packets from one site to another, the IP Precedence field (the first three bits of the DSCP field in the header of an IP packet) specifies the QoS. Based on the IP precedence marking, the packet is given the desired treatment such as the latency or the percent of bandwidth allowed for that quality of service. If the service provider network is an MPLS network, then the IP precedence bits are copied into the MPLS EXP field at the edge of the network. However, the service provider might want to set a QoS for a MPLS packet to a different value determined by the service offering.

This feature allows the service provider to set the MPLS experimental field instead of overwriting the value in the IP precedence field belonging to a customer. The IP header remains available for the customer’s use; the QoS of an IP packet is not changed as the packet travels through the MPLS network.

Table 25 QoS Services and Features

Service QoS Function Description

Packet classification

Committed access rate (CAR). Packets are classified at the edge of the network before labels are assigned.

Classifies packets according to input or output transmission rates. Allows you to set the MPLS experimental bits or the IP Precedence or DSCP bits (whichever is appropriate).

Congestion avoidance

Weighted Random Early Detection (WRED). Packet classes are differentiated based on drop probability.

Monitors network traffic to prevent congestion by dropping packets based on the IP Precedence or DSCP bits or the MPLS experimental field.

Congestion management

Class-based weighted fair queueing (CBWFQ). Packet classes are differentiated based on bandwidth and bounded delay.

An automated scheduling system that uses a queueing algorithm to ensure bandwidth allocation to different classes of network traffic.



Figure 35 shows an MPLS network that connects two sites of a IP network belonging to a customer.

Figure 35 MPLS Network Connecting Two Sites of a IP Network Belonging to a Customer

Note The network is bidirectional, but for the purpose of this document the packets move left to right.

In Figure 35, the symbols have the following meanings displayed in Table 26:

Note Notice that PE1 and PE2 are at the boundaries between the MPLS network and the IP network.

In Figure 35, the following behavior occurs:

• Packets arrive as IP packets at PE1, the provider edge router (also known as the ingress label switching router).

• PE1 sends the packets as MPLS packets.

• Within the service provider network, there is no IP Precedence field for the queueing mechanism to look at because the packets are MPLS packets. The packets remain MPLS packets until they arrive at PE2, the provider edge router.

• PE2 removes the label from each packet and forwards the packets as IP packets.

CE1

4186

7

PE1 P1 P2 PE2 CE2

IPnetwork

MPLSnetwork

IPnetwork

MPLSnetwork

Host A Host B

Owned byservice provider

Table 26 Device Symbols

Symbol Meaning

CE1 Customer equipment 1

PE1 Service provider edge router (ingress LSR)

P1 Service provider router within the core of the network of the service provider

P2 Service provider router within the core of the network of the service provider

PE2 Service provider edge router (egress LSR)

CE2 Customer equipment 2

Multiprotocol Label Switching OverviewMPLS Label Switch Controller


This MPLS QoS enhancement allows service providers to classify packets according to their type, input interface, and other factors by setting (marking) each packet within the MPLS experimental field without changing the IP Precedence or DSCP field. For example, service providers can classify packets with or without considering the rate of the packets that PE1 receives. If the rate is a consideration, the service provider marks in-rate packets differently from out-of-rate packets.

Note The MPLS experimental bits allow you to specify the QoS for an MPLS packet. The IP Precedence/DSCP bits allow you to specify the QoS for an IP packet.

MPLS Label Switch ControllerThe MPLS LSC, combined with slave ATM switch, supports scalable integration of IP services over an ATM network. The MPLS LSC enables the slave ATM switch to do the following:

• Participate in an MPLS network

• Directly peer with IP routers

• Support the IP features in Cisco IOS software

The MPLS LSC supports highly scalable integration of MPLS (IP+ATM) services by using a direct peer relationship between the ATM switch and MPLS routers. This direct peer relationship removes the limitation on the number of IP edge routers (typical of traditional IP-over-ATM networks), allowing service providers to meet growing demands for IP services. The MPLS LSC also supports direct and rapid implementation of advanced IP services over ATM networks using ATM switches.

MPLS combines the performance and VC capabilities of Layer 2 (data link layer) switching with the scalability of Layer 3 (network layer) routing capabilities. This combination enables service providers to deliver solutions for managing growth, providing differentiated services, and leveraging existing networking infrastructures.

The MPLS LSC architecture provides the following flexibility:

• Run applications over any combination of Layer 2 technologies

• Support any Layer 3 protocol while scaling the network to meet future needs

By deploying the MPLS LSC across large enterprise networks or wide area networks, you can achieve the following benefits:

• Save money by using existing ATM and routing infrastructures

• Grow revenue using MPLS-enabled services

• Increase productivity through enhanced network scalability and performance

MPLS LSC Functional DescriptionThe MPLS LSC is an LSR that is configured to control the operation of a separate ATM switch. Together, the MPLS LSC and the controlled ATM switch function as a single ATM MPLS router (ATM-LSR).



Figure 36 shows the functional relationship between the MPLS LSC and the ATM switch that it controls.

Figure 36 MPLS Label Switch Controller and Controlled ATM Switch

The following routers can function as an MPLS LSC:

• Cisco 7200 series router

• Cisco 6400 Universal Access Concentrator (UAC)

The following ATM switches can function with the Cisco 7200 series router as the controlled ATM switch:

• Cisco BPX 8600, 8650 (which includes a Cisco 7204 router), and 8680

• Cisco IGX 8410, 8420, and 8430

Note QoS is not an available feature with the IGX series ATM switches.

The MPLS LSC controls the ATM switch by means of the VSI, which runs over an ATM link connecting the two devices.

The dotted line in Figure 36 represents the logical boundaries of the external interfaces of the MPLS LSC and the controlled ATM switch, as discovered by the IP routing topology. The controlled ATM switch provides one or more XTagATM interfaces at this external boundary. The MPLS LSC can incorporate other label controlled or nonlabel controlled router interfaces.

MPLS LSC benefits are as follows:

• IP-ATM integration—Enables ATM switches to directly support advanced IP services and protocols, thereby reducing operational costs and bandwidth requirements, while at the same time decreasing time-to-market for new services.

• Explicit routing—Provides Layer 2 VCs to gigabit router backbones and integrated IP+ATM environments, including support for explicit routing and provisioning of IP VPN services.

• SVPNs—Supports IP-based VPNs on either a Frame Relay or ATM backbone, an integrated IP-ATM backbone, or a gigabit router backbone.

Label switch controller

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Other label controlled or nonlabeled controlledrouter interfaces

LC-ATM interfaceControlled ATM switch

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Using Controlled ATM Switch Ports as Router InterfacesIn the LSC, the XTagATM ports on the controlled ATM switch are used as a Cisco IOS interface type called extended Label ATM (XTagATM). To associate these XTagATM interfaces with particular physical interfaces on the controlled ATM switch, use the extended-port interface configuration command.

Figure 37 shows a typical MPLS LSC configuration that controls three ATM ports on a Cisco BPX switch: ports 6.1, 6.2, and 12.2. These corresponding XTagATM interfaces were created on the MPLS LSC and associated with the corresponding ATM ports on the Cisco BPX switch by means of the extended-port command.

Figure 37 Typical MPLS LSC and BPX Configuration

Figure 37 shows the following:

• An additional port on the Cisco BPX switch (port 12.1) acts as the switch control port

• An ATM interface (ATM1/0) on the MPLS LSC acts as the master control port

Using the MPLS LSC as a Label Edge Device

Note Using the MPLS LSC as a label edge device is not recommended. Using the MPLS LSC as a label edge device introduces unnecessary complexity to the configuration. Refer to the tag-switching atm disable-headend-vc command in the Cisco IOS Switching Services Command Reference to disable edge LSR functionality on the LSC.

Label Switch Controller(7200 series)

XTagATM61

extended-port a1/0BPX 6.1

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The MPLS LSC can perform as label edge device for the following purposes:

• Function simultaneously as a controller for an ATM switch and as a label edge device. Traffic can be forwarded between a router interface and an interface on the controlled switch, and between two XTagATM interfaces on the controlled switch.

• Perform label imposition and disposition and serve as the headend or tailend of a label-switched path tunnel.

However, when the MPLS LSC acts as a label edge device, it is limited by the following factors:

• Label space for LSC-terminated VCs is limited by the number of VCs supported on the control link.

• Packets are process switched between the LSC edge and an XTagATM interface.

• Throughput depends on the following factors:

– The slave switch VSI partition configuration of the maximum cells per second for the master control port interface and the XTagATM interface.

– SAR limitations of the ATM Lite (PA-A1) and ATM Deluxe (PA-A3) and process switching.

– CPU utilization for the LSC and edge LSR functionality.

Creating Virtual TrunksVirtual trunks provide connectivity for Cisco WAN MPLS switches through an ATM cloud, as shown in Figure 38. Because several virtual trunks can be configured across a given private or public physical trunk, virtual trunks provide a cost-effective means of connecting across an entire ATM network.

The ATM equipment in the cloud must support virtual path switching and transmission of ATM cells based solely on the VPI in the ATM cell header. The VPI is provided by the ATM cloud administrator (that is, by the service provider).

Typical ATM Hybrid Network with Virtual Trunks

Figure 38 shows three Cisco WAN MPLS switching networks, each connected to an ATM network by a physical line. The ATM network links all three of these subnetworks to every other subnetwork with a fully meshed network of virtual trunks. In this example, each physical interface is configured with two virtual trunks.



Figure 38 Typical ATM Hybrid Network Using Virtual Trunks

Benefits of virtual trunks are as follows:

• Reduced costs—By sharing the resources of a single physical trunk among a number of virtual (logical) trunks, each of the virtual trunks provided by the public carrier needs to be assigned only as much bandwidth as needed for that interface, rather than the full T3, E3, OC-3, or OC-12 bandwidth of an entire physical trunk.

• Migration of MPLS services into existing networks—VSI virtual trunks allow MPLS services to be carried over part of a network that does not support MPLS services. The part of the network that does not support such services may be a public ATM network, for example, that consists of switches that are not MPLS-enabled.

Virtual Trunk Configuration

A virtual trunk number (slot number.port number.trunk number) differentiates the virtual trunks found within a physical trunk port. In Figure 39, three virtual trunks (4.1.1, 4.1.2, and 4.1.3) are configured on a physical trunk that connects to the port 4.1 interface of a BXM switch.

Physicalinterface

Virtualtrunk

3396

2

ATM

MPLS MPLS

MPLS



Figure 39 Virtual Trunks Configured on a Physical Trunk

These virtual trunks are mapped to the XTagATM interfaces on the LSC. On the XTagATM interface, you configure the respective VPI value using the tag-switching atm vp-tunnel vpi interface command. This VPI should match the VPI in the ATM network. The LVCs are generated inside this Virtual Path (VP), and this VP carries the LVCs and their traffic across the network.

Virtual Trunk Bandwidth

The total bandwidth of all the virtual trunks on one port cannot exceed the maximum bandwidth of the port. Trunk loading (units of load) is maintained per virtual trunk, but the cumulative loading of all virtual trunks on a port is restricted by the transmit and receive rates for the port.

Virtual Trunk Features

The maximum number of virtual trunks that can be configured per card equals the number of virtual interfaces on the BPX or IGX switch. The following lists virtual interface support for BXM and UXM:

• The BXM supports 32 virtual interfaces; hence, it supports up to 32 virtual trunks. Accordingly, you can have interfaces ranging from XTagATM411 to XtagATM4131 on the same physical interface.

• The UXM supports 16 virtual interfaces. You can have interfaces ranging from XTagATM411 to XTagATM 4116.

Using LSC RedundancyThe following sections explain how LSC redundancy works:

• LSC Redundancy Architecture

• General Redundancy Operational Modes

• How LSC Redundancy Differs from Router and Switch Redundancy

• How the LSC, ATM Switch, and VSI Work Together

• Implementing LSC Redundancy

• Reducing the Number of LVCs for LSC Redundancy

4.1.1 (virtual trunk)

4.1.2 (virtual trunk)

4.1.3 (virtual trunk)...

4.1.31 (virtual trunk)Physical trunk(slot4 port 1) 33

963



LSC Redundancy Architecture

LSC redundancy allows you to create a highly reliable IP network, one whose reliability is nearly equivalent to that provided by Hot Standby routing. Instead of using Hot Standby routing processes to create redundancy, this method uses a combination of LSCs, the VSI, and IP routing paths with the same cost path for hot redundancy, or different costs for warm redundancy. The VSI allows multiple control planes (MPLS, Private Network-Network Interface (PNNI), and voice) to control the same switch. Each control plane controls a different partition of the switch.

In the LSC redundancy model, two independent LSCs control the different partitions of the switch. Thus, two separate MPLS control planes set up connections on different partitions of the same switch. This is where LSC redundancy differs from Hot Standby redundancy: the LSCs do not need copies of the other internal state to create redundancy; the LSCs control the partitions of the switch independently.

A single IP network consists of switches with one LSC (or a Hot Standby pair of LSCs) and MPLS edge LSRs.

If you change that network configuration by assigning two LSCs per switch, you form two separate MPLS control planes for the network. You logically create two independent parallel IP subnetworks linked at the edge.

If the two LSCs on each switch are assigned identical shares of switch resources and links, the two subnetworks are identical. You have two identical parallel IP subnetworks on virtually the same equipment, which would otherwise support only one network.

For example, Figure 40 shows a network of switches that each have two LSCs. MPLS edge LSRs are located at the edge of the network, to form a single IP network. The LSCs on each switch have identical shares of switch resources and links, which makes the networks identical. In other words, there are two identical parallel IP subnetworks.

Figure 40 LSC Redundancy Model

LSC-1

ATM-LSR-1

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Edge LSR

Physical LSC redundant network

Logical equivalent

Edge LSR

Edge LSR Edge LSR

3514

9

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Part of the redundancy model includes edge LSRs, which link the two networks at the edge.

If the network uses OSPF or a similar IP routing protocol with an equal cost on each path, then there are at least two equally viable paths from every edge LSR to every other edge LSR. The OSPF equal-cost multipath distributes traffic evenly on both paths. Therefore, MPLS sets up two identical sets of connections for the two MPLS control planes. IP traffic travels equally across the two sets of connections.

Note The LSC redundancy model works with any routing protocol. For example, you can use OSPF or IS-IS. Also, you can use both the TDP and the LDP.

With the LSC redundancy model, if one LSC on a switch fails, IP traffic uses the other path, without needing to establish new links. LSC redundancy does not require the network to set up new connections when a controller fails. Because the connections to the other paths have already been established, the interruption to the traffic flow is negligible. The LSC redundancy model is as reliable as networks that use Hot Standby controllers. LSC redundancy requires hardware like that used by Hot Standby controllers. However, the controllers act independently, rather than in Hot Standby mode. For LSC redundancy to work, the hardware must have connection capacity for doubled-up connections.

If an LSC fails and LSC redundancy is not present, IP traffic halts until other switches break their present connections and reroute traffic around the failed controller. The stopped IP traffic results in undesirable unreliability.

General Redundancy Operational Modes

The LSC redundancy model allows you to use the following four operational models. Most other redundancy models cannot accommodate all of these redundancy models.

• Transparent Mode—The primary and secondary redundant systems have the same copies of the image and startup configurations. When one system fails, the other takes over, and the operations are identical. However, this mode risks software failures, because both systems use the same algorithms. A software problem on the primary system is likely to affect the secondary system as well.

• Upgrade mode—You can upgrade the image or configuration of the redundant system, without rebooting the entire system. You can use this mode to change the resources between different partitions of the slave ATM switch.

• Nontransparent mode—The primary and secondary systems have different images or configurations. This mode is more reliable than transparent mode, which loads the same software on both controllers. In nontransparent mode, the use of different images and configurations reduces the risk of both systems encountering the same problem.

• Experimental mode—You load an experimental version of the image or configuration on the secondary system. You can use experimental mode when you want to test the new images in a real environment.

How LSC Redundancy Differs from Router and Switch Redundancy

In traditional IP router networks, network managers ensure reliability by creating multiple paths through the network from every source to every destination. If a device or link on one path fails, IP traffic uses an alternate path to reach its destination.



Router Redundancy

Because routers need not establish a VC to transfer data, they are inherently connectionless. When a router discovers a failed device or link, it requires approximately less than 1 second to reroute traffic from one path to another.

Routers can incorporate a warm or Hot Standby routing process to increase reliability. The routing processes share information about the routes to direct different streams of IP traffic. They need not keep or share connection information. Routers can also include redundant switch fabrics, backplanes, power supplies, and other components to decrease the chances of node failures.

ATM, Frame Relay, and Circuit Switch Redundancy

ATM, Frame Relay, and circuit switch networks transfer data by establishing circuits or VCs. To ensure the transfer of data in switches, network managers incorporate redundant switch components. If any component fails, a spare component takes over. Switches can have redundant line cards, power supplies, fans, backplanes, switch fabrics, line cards, and control cards. The following describes these redundant components:

• The redundant backplanes include all the hardware to operate two backplanes and to switch to the backup backplane if one fails.

• Redundant line cards protect against failed links. If a link to a line card fails, the redundant line card takes over. To create redundant line cards, you must program the same connection information into both line cards. This ensures that the circuits or VCs are not disrupted when the new line card takes over.

• The redundant switch fabric must also have the same connection information as the active switch fabric.

A software application usually monitors the state of the switches and their components. If a problem arises, the software sets an alarm to bring attention to the faulty component.

The redundant switch hardware and software are required, because switches take some time to reroute traffic when a failure occurs. Switches can have connection routing software, such as Cisco automatic connection routing, PNNI, or MPLS. However, rerouting the connections in a switch takes much more time than rerouting traffic in a router network. Rerouting connections in a switch requires calculating routes and reprogramming some hardware for each connection. In router networks, large aggregates of traffic can be rerouted simultaneously, with little or no hardware programming. Therefore, router networks can reroute traffic more quickly and easily than connection oriented networks. Router networks rely on rerouting techniques to ensure reliability. Connection-oriented networks use rerouting only as a last resort.

General Hot/Warm Standby Redundancy in Switches

Network managers can install redundant copies of the connection routing software for ATM and Frame Relay switches on a redundant pair of control processors.

With Hot Standby redundancy, the active process sends its state to the spare process to keep the spare process up to date in case it needs to take over. The active process sends the state information to the spare process or writes the state to a disk, where both processes can access the information. In either case, the state information is shared between controllers. Because the state of the network routing tables changes frequently, the software must perform much work to maintain consistent routing states between redundant pairs of controllers.

With Warm Standby redundancy, the state information is not shared between the active and spare processes. If a failure occurs, the spare process resets all of the connections and reestablishes them. Reliability decreases when the spare resets the connections. The chance of losing data increases.



LSC Redundancy

Connecting two independent LSCs to each switch by the VSI creates two identical subnetworks. Multipath IP routing uses both subnetworks equally. Thus, both subnetworks have identical connections. If a controller in one subnetwork fails, the multipath IP routing diverts traffic to the other path. Because the connections already exist in the alternate path, the reroute time is very fast. The LSC redundancy model matches the reliability of networks with Hot Standby controllers, without the difficulty of implementing Hot Standby redundancy.

One benefit of implementing the LSC redundancy model is that you eliminate the single point of failure between the LSC and the ATM switch it controls. If one LSC fails, the other LSC takes over and routes the data on the other path. The following sections explain the other benefits of LSC redundancy.

LSC Redundancy Does Not Use Shared States or Databases

In the LSC redundancy model, the LSCs do not share states or databases, which increases reliability. Sometimes, when states and databases are shared, an error in the state or database information can cause both controllers to fail simultaneously.

Also, new software features and enhancements do not affect LSC redundancy. Because the LSCs do not share states or database information, you need not worry about ensuring redundancy during every step of the update.

LSC Redundancy Allows Different Software Versions

The LSCs work independently and there is no interaction between the controllers. They do not share the state or database of the controller, as other redundancy models require. Therefore, you can run different versions of the Cisco IOS software on the LSCs, which provides the following advantages:

• You can test the features of the latest version of software without risking reliability. You can run the latest version of the Cisco IOS software on one LSC and an older version of the Cisco IOS software on a different LSC. If the LSC running the new Cisco IOS software fails, the LSC running the older software takes over.

• Running different versions of the Cisco IOS software reduces the chance of having both controllers fail. If you run the same version of the Cisco IOS software on both controllers and that version contains a problem, it could cause both controllers to fail. Running different versions on the controllers eliminates the possibility of each controller failing because of the same problem.

Note Using different Cisco IOS software version on different LSCs is recommended only as a temporary measure. Different versions of Cisco IOS software in a network could be incompatible, although it is unlikely. For best results, run the same version of Cisco IOS software on all devices.

LSC Redundancy Allows Different Hardware

You can use different models of routers in this LSC redundancy model. For example, one LSC can be a Cisco 7200 series router, and the other LSC can be a Cisco 7500 series router. Using different hardware in the redundancy model reduces the chance that a hardware fault would interrupt network traffic.

LSC Redundancy Allows You to Switch from Hot to Warm Redundancy Immediately

You can implement hot or warm redundancy and switch from one model to the other. Hot redundancy can use redundant physical interfaces, slave ATM switches with Y redundancy, and redundant LSCs to enable parallel paths and near-instant failover. If your resources are limited, you can implement warm



redundancy, which uses only redundant LSCs. When one controller fails, the backup controller requires some reroute time. As your network grows, you can switch from hot to warm redundancy and back, without bringing down the entire network.

Other redundancy models require complex hardware and software configurations, which are difficult to alter when you change the network configuration. You must manually change the connection routing software from Hot Standby mode to Warm Standby mode.

LSC Redundancy Provides an Easy Migration from Standalone LSCs to Redundant LSCs

You can migrate from a standalone LSC to a redundant LSC and back again without affecting network operations. Because the LSCs work independently, you can add a redundant LSC without interrupting the other LSC.

LSC Redundancy Allows Configuration Changes in a Live Network

The hot LSC redundancy model provides two parallel, independent networks. Therefore, you can disable one LSC without affecting the other LSC. This feature has the following benefits:

• LSC redundancy model facilitates configuration changes and updates. After you finish with configuration changes or image upgrades to the LSC, you can add it back to the network and resume the LSC redundancy model.

• The redundancy model protects the network during partitioning of the ATM switch. You can disable one path and perform partitioning on that path. While you are performing the partitioning, data uses the other path. The network is safe from the effects of the partitioning, which include breaking or establishing LVC connections.

LSC Redundancy Provides Fast Reroute in IP+ATM Networks

The hot LSC redundancy model offers redundant paths for every destination. Therefore, reroute recovery is very fast. Other rerouting processes in IP+ATM networks require many steps and take longer to reroute.

In normal IP+ATM networks, the reroute process consists of the following steps:

• Detecting the failure

• Converging the Layer 2 routing protocols

• Completing label distribution for all destinations

• Establishing new connections for all destinations

After this reroute process, the new path is ready to transfer data. Rerouting data using this process takes time.

The hot LSC redundancy method allows you to quickly reroute data in IP+ATM networks without using the normal reroute process. When you incorporate hot LSC redundancy, you create parallel paths. Every destination has at least one alternative path. If a device or link along the path fails, the data uses the other path to reach its destination. The hot LSC redundancy model provides the fastest reroute recovery time for IP+ATM networks.



How the LSC, ATM Switch, and VSI Work Together

In an LSC implementation, the LSC and slave ATM switch have the following characteristics:

• The LSC runs all of the control protocols.

• The ATM switch forwards the data.

• Each physical interface on the slave ATM switch maps to an XTagATM interface on the LSC. Each XTagATM interface has a dedicated LDP session with a corresponding interface on the edge. The XTagATM interfaces are mapped in the routing topology, and the ATM switch behaves as a router.

• The LSC can also function as an edge LSR. The data for the edge LSR passes through the control interface of the router.

If a component on the LSC fails, the IP switching function of the ATM switch is disabled. The standalone LSC is the single point of failure.

The VSI implementation includes the following characteristics:

• The VSI allows multiple, independent control planes to control a switch. The VSI ensures that the control processes (Signaling System 7 (SS7), MPLS, PNNI, and so on) can act independently of each other by using a VSI slave process to control the resources of the switch and apportion them to the correct control planes.

• In MPLS, each physical interface on the slave ATM switch maps to an XTagATM interface on the LSC through the VSI. In other words, physical interfaces are mapped to their respective logical interfaces.

• The routing protocol on the LSC generates route tables entries. The master sends connection requests and connection release requests to the slave.

• The slave sends the configured bandwidth parameters for the ATM switch interface to the master in the VSI messages. The master includes the bandwidth information in the link-state topology. You can override these bandwidth values by manually configuring the bandwidth on the XTagATM interfaces.

Implementing LSC Redundancy

To make an LSC redundant, you can partition the resources of the slave ATM switch, implement a parallel VSI model, assign redundant LSCs to each switch, and create redundant LSRs. The following sections explain these steps.



Partitioning the Resources of the ATM Switch

In the LSC redundancy model, two LSCs control different partitions of the ATM switch. When you partition the ATM switch for LSC redundancy, use the following guidelines:

• Make the MPLS partitions identical. If you create two partitions, make sure both partitions have the same amount of resources. (You can have two MPLS VSI partitions per switch.) Use the cnfrsrc router configuration command to configure the partitions.

• If the partitions are on the same switch card, perform the following steps:

– Create different control VCs for each partition. For example, there can be only one (0, 32) control VC on the XTagATM interface. To map two XTagATM interfaces on the same ATM switch interface, use a different control VC for the second LSC. Use the tag-switching atm control-vc interface command.

– Create the LVC on the XTagATM interfaces using nonintersecting VPI ranges. Use the tag-switching atm vpi interface command.

• Specify the bandwidth information on the XTagATM interfaces. Normally, this information is read from the slave ATM switch. When you specify the bandwidth on the XTagATM interface, the value you enter takes precedence over the switch-configured interface bandwidth.

• Configure the logical channel number (LCN) ranges for each partition according to the expected number of connections.

See the documentation on the Cisco BPX 8600 series or Cisco IGX 8400 series switches for more information about configuring the slave ATM switch.

Implementing the Parallel VSI Model

The parallel VSI model means that the physical interfaces on the ATM switch are shared by more than one LSC. For instance, LSC1 in Table 26 maps VSI slave interfaces 1 to N to the ATM switch physical interfaces 1 to N. LSC2 maps VSI slave interfaces to the ATM switch’s physical interfaces 1 to N. LSC1 and LSC2 share the same physical interfaces on the ATM switch. With this mapping, you achieve fully meshed independent masters.

Figure 41 shows four ATM physical interfaces mapped as four XTagATM interfaces at LSC1 and LSC2. Each LSC is not aware that the other LSC is mapped to the same interfaces. Both LSCs are active all the time. The ATM switch runs the same VSI protocol on both partitions.

Figure 41 XTagATM Interfaces

XtagATMinterfaces

Controlport

Controlport

4846

8

LSC 1

ATM Switch

VSI 1 VSI 2

LSC 2



Adding Interface Redundancy

To ensure reliability throughout the LSC redundant network, you can also implement:

• Redundant interfaces between the edge LSR and the ATM-LSR. Most edge LSRs are collocated with the LSCs. Creating redundant interfaces between the edge LSRs and the ATM LSRs reduces the chance of a disruption in network traffic by providing parallel paths.

• Redundant virtual trunks and VP tunnels between slave ATM switches. To ensure hot redundancy between the ATM switches, you can create redundant virtual trunks and VP tunnels. See Figure 42.

Figure 42 Interface Redundancy

Implementing Hot or Warm LSC Redundancy

Virtually any configuration of switches and LSCs that provides hot redundancy can also provide warm redundancy. You can also switch from warm to hot redundancy with little or no change to the links, switch configurations, or partitions.

Hot and warm redundancy differ in the following ways:

• Hot redundancy uses both paths to route traffic. You set up both paths using equal-cost multipath routing, so that traffic is load balanced between the two paths. As a result, hot redundancy uses twice the number of MPLS label VCs as warm redundancy.

• Warm redundancy uses only one path at a time. You set up the paths so that one path has a higher cost than the other. Traffic only uses one path and the other path is a backup path.

The following sections explain the two redundancy models in detail.

Implementing Hot LSC Redundancy

Hot redundancy provides near-instant failover to the other path when an LSC fails. When you set up hot redundancy, both LSCs are active and have the same routing costs on both paths. To ensure that the routing costs are the same, run the same routing protocols on the redundant LSCs.

In hot redundancy, the LSCs run parallel and independent LDPs. At the edge LSRs, when the LDP has multiple routes for the same destination, it requests multiple labels. It also requests multiple labels when it needs to support QoS. When one LSC fails, the labels distributed by that LSC are removed.

3515

0

ATMnetworks

LSC LSC LSC

Edge LSR Edge LSRATM switch ATM switch

LSC LSC

Edge LSR

ATM switchPhysical interface

Virtual trunk

Virtual Trunk/VP Tunnel

Virtual trunk/VP tunnel

LSC



To achieve hot redundancy, you can implement the following redundant components:

• Redundant physical interfaces between the edge LSR and the ATM-LSR to ensure reliability in case one physical interface fails.

• Redundant interfaces or redundant VP tunnels between the ATM switches.

• Slave ATM switches, such as the BPX 8650, can have redundant control cards and switch fabrics. If redundant switch fabrics are used and the primary switch fails, the other switch fabric takes over.

• Redundant LSCs.

• The same routing protocol running on both LSCs. (You can have different tag or label distribution protocols.)

Figure 43 shows one example of how hot LSC redundancy can be implemented.

Figure 43 Hot LSC Redundancy

Implementing Warm LSC Redundancy

To achieve warm redundancy, you need only redundant LSCs. You need not run the same routing protocols or distribution protocols on the LSCs.

Note You can use different routing protocols on parallel LSCs. However, you do not get near-instant failover. The failover time includes the time it takes to reroute the traffic, plus the LDP bind request time. If the primary routing protocol fails, the secondary routing protocol finds new routes and creates new LVCs. An advantage to using different routing protocols is that the ATM switch uses fewer resources and offers more robust redundancy.

LSC-1

ATM-LSR-1

ATM switch

Edge LSR


Logical equivalent

Edge LSR

Edge LSR Edge LSR35

149

ATM switch

LSC-2

ATM-LSR-2

ATM-LSR-3

ATM-LSR-4

LSC-3 LSC-4



If you run the same routing protocols, specify a higher cost for the interfaces on the backup LSC to allow the data to use only the lower-cost path and also saves resources on the ATM switch (the edge LSR requests LVCs only through the lower-cost LSC). When the primary LSC fails, the edge LSR uses the backup LSC and creates new paths to the destination. Creating new paths requires reroute time and LDP negotiation time.

Figure 44 shows one example of how warm LSC redundancy can be implemented.

Figure 44 Warm LSC Redundancy

Reducing the Number of LVCs for LSC Redundancy

By default, an LSC includes edge LSR functionality, which means that the LSC can act as a label edge device. To achieve the edge LSR functionality, the LSC creates an LSP for each destination in the route table.

With LSC redundancy, if 400 destinations exist in the network, each redundant LSC adds 400 headend VCs. In hot redundancy mode, 800 headend VCs are created for the LSCs. If the LSCs are not edge LSRs, then 800 LVCs are wasted.

The number of LVCs increases as the number of redundant LSCs increases. In the case of a VC-merged system, the number of LVCs can be low. However, in non-VC-merged system, the number of LVCs can be high. To reduce the number of LVCs, disable the edge LSR functionality in the LSC. Enter the tag-switching atm disable headend-vc interface command to disable the edge LSR functionality on the LSC and prevent the creation of headend VCs.

LSC-1

ATM-LSR-1

ATM switch

Virtual trunk/VP tunnel 4






Edge LSR

Note: Tunnels are virtual interfaces.Physical interfaces are marked by thin lines.


Logical equivalent

Edge LSR

Edge LSR Edge LSR

3515

2

ATM switch

LSC-2

ATM-LSR-2

ATM-LSR-3

ATM-LSR-4

LSC-3 LSC-4



Note As an alternative to the tag-switching atm disable headend-vc interface command, you can issue the tag-switching request-tags for interface command with an access list to save LVC space.

For more information on reducing the number of LVCs, see the “Reducing the Number of Label Switch Paths Created in an MPLS Network” section.

Implementation Considerations

The following sections explain items that need to be considered when implementing hot or warm LSC redundancy in a network.

Hot LSC Redundancy Considerations

The following list explains the items you need to consider when implementing hot LSC redundancy:

• LSC hot redundancy needs parallel paths. Specifically, there must be the capacity for at least two end-to-end parallel paths traveling from each source to each destination. Each path is controlled by one of a pair of redundant LSCs.

• LSPs for the destinations are initiated from the edge LSR. The edge LSR initiates multiple paths for a destination only if it has parallel paths to its next hop. Therefore, it is important to have parallel paths from the edge LSR. You can achieve parallel paths by having two physical links from the edge LSR or by having two separate VP tunnels on one link.

• Hot redundancy protection extends from the edge LSR only as far as parallel paths are present. So, it is best if parallel paths are present throughout the entire network.

• Hot redundancy increases the number of VCs used in the network. Each physical link with two VSI partitions has twice the number of VCs used than would otherwise be the case. Various techniques can be used to alleviate VC usage. The use of unnumbered links (“ip unnumbered” in the Cisco IOS link configuration) reduces the number of routes in the routing table and hence the number of VCs required. On the LSCs, you can use the tag-switching atm disable headend-vc interface command to disable edge LSR functionality on the LSC and also reduce the number of VCs used. The tag-switching request-tags for interface command with an access list also restricts the creation of LVCs.

Warm LSC Redundancy Considerations

The following list explains the items you need to consider when implementing warm LSC redundancy:

• LSC warm redundancy needs a single active path between the source and destination. However, there is also a requirement for end-to-end parallel paths, as in the hot redundancy case. Only one path has an active LSP for the destination. In the event of the failure, the other path is established, with some delay due to rerouting.

• The number of VCs in the network does not change with the warm redundancy.

• Hot LSC redundancy achieves failure recovery with little loss of traffic. However, hot redundancy doubles the VC requirements in the network. Warm LSC redundancy requires the same number of VCs as a similar network without LSC redundancy. However, traffic loss due to a failure is greater; traffic may be lost for a period of seconds during rerouting.



Note The precise traffic loss depends on the type of failure. If the failure is in an LSC, the LSPs controlled by that LSC typically remain connected for some time. Traffic can still flow successfully on the “failed” path until the edge LSRs switch all traffic to the alternate path (which might occur tens of seconds later, depending on routing protocol configuration). The only traffic loss might occur in the edge LSR when traffic changes to the new path, which typically takes a few milliseconds or less.

Reducing the Number of Label Switch Paths Created in an MPLS NetworkYou can use two methods to reduce the number of LSPs created in an MPLS network:

• Disable LSPs from being created from a edge LSR or LSC to a destination IP address. Use the tag-switching request-tags for interface command. Specify the destination IP addresses that you want to disable from creating LSPs. This command allows you to permit creation of some LSPs, while preventing the creation of others.

• Disable the LSC from acting as an edge LSR by using the tag-switching atm disable headend-vc interface command. This command removes all LSPs that originate at the MPLS LSC and disables the LSC from acting as an edge LSR.

Using an Access List to Disable Creation of LSPs to Destination IP Addresses

You can prevent LSPs from being created between edge LSRs and LSCs to prevent the unnecessary use of LVC resources in a slave ATM switch. Use the tag-switching request-tags for interface command with an access list to disable the creation of the LSPs.

Some LSPs are often unnecessary between some edge LSRs in an MPLS network. Every time a new destination is created, LSPs are created from all edge LSRs in the MPLS network to the new destination. You can create an access list at an edge LSR or LSC to restrict the destinations for which a downstream-on-demand request is issued.

For example, Figure 45 is an MPLS ATM network that consists of the following elements:

• The PE routers in the VPN require LSPs to communicate with each other.

• All the PE routers are in network 1 (198.x.x.x).

• All the IGP IP addresses are in network 2 (192.x.x.x).

• If numbered interfaces are required (for network management or other purposes), they are placed in network 2 (192.x.x.x).

Use tag-switching request-tags for interface commands to accomplish the following tasks:

• Allow the PE routers in network 1 to create LSPs and communicate with each other.

• Prevent LSPs from being created in network 2.

Performing these tasks reduces the number of LSPs in the MPLS ATM cloud, which reduces the VC usage in the cloud.



Figure 45 Sample MPLS ATM Network

Note When using access lists to prevent the creation of headend LVCs or LSPs, do not disable the LSC from acting as an edge LSR with the tag-switching disable headend-vc interface command, which prevents all LSPs from being established.

CE routerCE router

CE routerCE routerPE router

192.168.x.xPE router

192.168.x.x

PE router192.168.x.x

PE router192.168.x.x

MPLS ATMNetwork

IGP172.16.x.x

4692

8



The following examples of the tag-switching request tags-for interface command use Figure 46 as a basis. The examples show different ways to disable the creation of LSPs from the LSC to the edge LSR, and from the edge LSRs to the LSC.

Figure 46 Sample Configuration

Using a Numbered Access List

The following examples use a numbered access list to restrict creation of LSPs.

Preventing LSPs from the LSC to the Edge LSRs

The following example prevents LSPs from being established from the LSC to all 198.x.x.x destinations. However, transit LSPs are allowed between 198.x.x.x destinations. Add the following commands to the LSC configuration:

tag-switching request-tags for 1access-list 1 deny 198.0.0.0 0.255.255.255access-list 1 permit any

Preventing LSPs from the Edge LSRs to the LSC

The following example prevents headend LVCs from being established from edge LSR 1 and edge LSR 2 to the LSC (192.x.x.x). However, transit LSPs are allowed between 198.x.x.x destinations. Add the following commands to the edge LSR 1 and 2 configurations:


Using a Named Access List

The following examples use a named access list to perform the same tasks as in the previous examples:

tag-switching request-tags for nolervcsip access-list standard nolervcsdeny 198.0.0.0 0.255.255.255permit any

tag-switching request-tags for nolervcsip access-list standard nolervcsdeny 192.0.0.0 0.255.255.255permit any

LSC172.16.53.1

Edge LSR 1192.168.0.1

ATM switch Edge LSR 2192.168.0.2

4556

6



Specifying Exact Match IP Addresses with an Access List

The following examples use exact IP addresses to perform the same tasks as in the previous examples:

tag-switching request-tags for 1access-list 1 deny 198.5.0.1 0.0.0.0access-list 1 deny 198.5.0.2 0.0.0.0access-list 1 permit any


Instead of configuring an access list on the LSC, you can issue the tag-switching atm disable-headend-vc interface command to disable the creation of LSPs. This command works only with LSCs.

Disabling the LSC from Acting as an Edge LSR

To remove all LSPs from the MPLS LSC and disable its ability to function as an edge LSR, you can use either of the following interface commands:

• tag-switching atm disable-headend-vc

• tag-switching request-tags for

Disabling the LSC from acting as an edge LSR causes the LSC to stop initiating LSPs to any destination. Therefore, the number of LVCs used in the network is reduced. The LSC can still terminate tailend LVCs, if required.

With downstream on demand, LVCs are depleted with the addition of each new node. These commands save resources by disabling the LSC from setting up unwanted LSPs. The absence of those LSPs allows traffic to follow the same path as control traffic.

The following example uses the tag-switching atm disable-headend-vc interface command to disable the LSC from functioning as an edge LSR. The following line is added to the LSC configuration:

tag-switching atm disable-headend vc

The following example uses the tag-switching request-tags for interface command to disable the LSC from functioning as an edge LSR. The following lines are added to the LSC configuration:

tag-switching request-tags for dedicatedlscip access-list standard dedicatedlscdeny any

Note For a Cisco 6400 UAC with an NRP configured to function as an LSC, disable the LSC from acting as an edge LSR. An NRP LSC should only support label switch paths through the controlled ATM switch under VSI control.

Using the Cisco 6400 Universal Access Concentrator as an MPLS LSCYou can configure the Cisco 6400 UAC to operate as an MPLS LSC in an MPLS network. The hardware that supports MPLS LSC functionality on the Cisco 6400 UAC is described in the following sections.



Note If you configure a Cisco 6400 UAC with a node resource processor (NRP) to function as an LSC, disable MPLS edge LSR functionality. Refer to the tag-switching atm disable-headend-vc command in the Cisco IOS Switching Services Command Reference for information on disabling MPLS edge LSR functionality. An NRP LSC should support transit label switch paths only through the controlled ATM switch under VSI control.

Cisco 6400 UAC Architectural Overview

A Cisco 6400 UAC can operate as an MPLS LSC if it incorporates the following components:

• Node switch processor (NSP)—The NSP incorporates an ATM switch fabric, enabling the Cisco 6400 UAC to function as ATM-LSR in a network. The NSP manages all the external ATM interfaces for the Cisco 6400 UAC.

• NRP—The NRP enables a Cisco 6400 UAC to function as an LSC. When you use the NRP as an LSC, however, you must not configure the NRP to perform other functions.

The NRP contains internal ATM interfaces that enable it to be connected to the NSP. However, the NRP cannot access the external ATM interfaces of the Cisco 6400 UAC. Only the NSP can access the external ATM interfaces.

Note A Cisco 6400 UAC chassis can accommodate multiple NRPs, including one dedicated to MPLS LSC functions. You cannot use an additional NRP as an MPLS LSC. However, you can use additional NRPs to run MPLS and perform other networking services.

• ATM port adapter—The Cisco 6400 UAC uses an ATM port adapter to provide external connectivity for the NSP.



Figure 47 shows the components that you can configure to enable the Cisco 6400 UAC to function as an MPLS LSC.

Figure 47 Cisco 6400 UAC Configured as an MPLS LSC

Configuring Permanent Virtual Circuits and Permanent Virtual Paths

The NRP controls the slave ATM switch through the VSI protocol. The VSI protocol operates over a PVC that you configure. The PVC is dedicated to the VCs that the VSI control channel uses.

For the NRP to control an ATM switch through the VSI, cross-connect the control VCs from the ATM switch through the NSP to the NRP. The ATM switch (BPX) uses defined control VCs for each BXM slot of the BPX chassis, enabling the LSC to control external XTagATM interfaces through the VSI.

Table 27 defines the PVCs that must be configured on the NSP interface connected to the BPX VSI shelf. These PVCs are cross-connected via the NSP to the NRP VSI master control port, which is running the VSI protocol.

For an NRP that is installed in slot 3 of a Cisco 6400 UAC chassis, the master control port would be ATM3/0/0 on the NSP. As shown in Figure 37, the BPX switch control interface is 12.1, and the NSP ATM port connected to this interface is the ATM interface that is cross-connected to ATM3/0/0. Because

NSP

Edge

LSR

Additional NRPs cansupport MPLS andIP Layer 3 services

Cisco 6400 UAC chassis

ATM port adapterprovides externalATM connectivityfor NSP

NSP supports ATMswitching functionsfor Cisco 6400 UAC

NRP supports LSC functions forCisco 6400 UAC

NRP1

3078

7

NRP2

LSC

.

.

x

PVP(n)

PVP(n+3)

PVP(n+3)

PVP(n)

.

.

x

x PVPPVP

Legend: x = switch fabric



Figure 37 shows that the BXM slaves in BPX slots 6 and 12 are configured as external XTagATM ports, the PVCs that must be cross-connected through the NSP are 0/45 for slot 6 and 0/51 for slot 12, respectively, as outlined in Table 27.

Figure 48 shows the functional relationships among the Cisco 6400 UAC hardware components and the permanent virtual paths (PVPs) that you can configure to support MPLS LSC functionality.

Figure 48 Cisco 6400 UAC PVP Configuration for MPLS LSC Functions

Table 27 VSI Interface Control PVCs for BPX VSI Slave Slots

BPX VSI Slave Slot VSI Interface Control VC

1 0/40

2 0/41

3 0/42

4 0/43

5 0/44

6 0/45

7 0/46

8 0/47

9 0/48

10 0/49

11 0/50

12 0/51

13 0/52

14 0/53

Slave ATM switch NSP NRP

I/F = xtag2VC = 2/83mapped to0/32

I/F = xtag1VC = 2/35mapped to0/32

PVP for VSIcontrol channel

VSI interface

VC = 2/83

VC = 2/35

VP = n fromNSP to

slave ATM switchPVPs for

LSC functionsVP = n fromNSP to NRP

VC = 0/32 VC = 0/32

Cisco 6400 UAC

6.1 12.2

2975

2



All other MPLS LSC functions, such as routing, terminating LVCs, and LDP control VCs (default 0/32), can be accomplished by means of a separate, manually configured PVP (see the upper shaded area in Figure 48). The value of “n” for this manually configured PVP must be the same among all the associated devices (the NRP, the NSP, and the slave ATM switch). Because the NSP uses VP = 0 for ATM Forum signalling and the BPX uses VP = 1 for autoroute, the value of “n” for this PVP for MPLS LSC functions must be greater than or equal to 2, while not exceeding an upper bound.

Note that some edge LSRs have ATM interfaces with limited VC space per virtual path (VP). For these interface types, you define several VPs. For example, the Cisco ATM Port Adapter (PA-A1) and the AIP interface are limited to VC range 33 through 1018. To use the full capacity of the ATM interface, configure four consecutive VPs. Make sure the VPs are within the configured range of the BPX.

For internodal BPX connections, we suggest that you configure VPs 2 through 15; for edge LSRs, we suggest that you configure VPs 2 through 5. (Refer to the BPX cnfrsrc command in the Cisco BPX 8600 Series documentation for examples of how to configure BPX service nodes.)

Control VC Setup for MPLS LSC Functions

After you connect the NRP, the NSP, and the slave ATM switch by means of manually configured PVPs (as shown in Figure 48), the NRP can control the slave ATM switch as though it is directly connected to the NRP. The NRP discovers the interfaces of the slave ATM switch and establishes the default control VC to be used in creating MPLS VCs.

The slave ATM switch shown in Figure 48 incorporates two external ATM interfaces (labeled xtag1 and xtag2) that are known to the NRP as XTagATM61 and XTagATM122, respectively. On interface 6.1 of the slave ATM switch, VC = 0/32 is connected to VC 2/35 by the VSI protocol. On the NRP, VC 2/35 is terminated on interface XTagATM61 and mapped to VC 0/32, also by means of the VSI protocol. This mapping enables the LDP to discover MPLS LSC neighbors by means of the default control VC 0/32 on the physical interface. On interface 12.2 of the slave ATM switch, VC 0/32 is connected to VC 2/83 by the VSI protocol. On the NRP, VC 2/83 is terminated on interface XTagATM122 and mapped to VC 0/32.

Note that the selection of these VCs is dependent on the availability of VC space. Hence it is not predictable which physical VC will be mapped to the external default control VC 0/32 on the XTagATM interface. The control VC will be shown as a PVC on the LSC, as opposed to an LVC, when you enter the Cisco IOS show xtagatm vc EXEC command.



Configuring the Cisco 6400 UAC to Perform Basic MPLS LSC Operations

Figure 49 shows a Cisco 6400 UAC containing a single NRP that has been configured to perform basic MPLS LSC operations.

Figure 49 Typical Cisco 6400 UAC Configuration to Support MPLS LSC Functions

Note If the NRP incurs a fault that causes it to malfunction (in a single NRP configuration), the LVCs and routing paths pertaining to MPLS LSC functions are lost.

Note The loopback addresses must be configured with a 32-bit mask and be included in the relevant IGP or BGP routing protocol, as shown in the following example:ip address 192.103.210.5 255.255.255.255

Defining the MPLS Control and IP Routing Paths

In the MPLS LSC topology shown in Figure 49, the devices labeled LSR1 and LSR2 are external to the Cisco 6400 UAC. These devices, with loopback addresses as their respective LDP identifiers, are connected to two separate interfaces labeled 6.1 and 12.2 on the slave ATM switch. Both LSR1 and LSR2 learn about the routes of each other from the NRP by means of the data path represented as the thick dashed line in Figure 49. Subsequently, LVCs are established by means of LDP operations to create the data paths between LSR1 and LSR2 through the ATM slave switch.

Both LSR1 and LSR2 learn of the loopback address of the NRP and create a data path (LVCs) from each other that terminates in the NRP. These LVCs, called tailend LVCs, are not shown in Figure 49.

Slave ATM switch NSP NRP

6.1 12.2

Cisco 6400 UAC

LSR1 LSR2

Io = 2.2.2.2 Io = 3.3.3.3

LDP and routing pathsbetween LSR1 and LSR2Data path between

LSR1 and LSR2 fortheir respective

networks

Loopback = 1.1.1.1

2975

3

Multiprotocol Label Switching OverviewMPLS Egress NetFlow Accounting


Disabling Edge LVCs

By default, the NRP requests LVCs for the next hop devices (the LSRs shown in Figure 49). The headend LVCs enable the LSC to operate as an edge LSR. Because the NRP is dedicated to the slave ATM switch by default, the headend LVCs are not required.

Note If a Cisco 6400 UAC with an NRP is configured to function as an LSC, disable the edge LSR functionality. An NRP LSC should support transit LSPs only through the controlled ATM switch under VSI control. Refer to the tag-switching atm disable-headend-vc interface command in the Cisco IOS Switching Services Command Reference to disable edge LSR functionality.

The tag-switching atm disable-headend-vc command disables the default behavior of the NRP in setting up headend switch LVCs, thereby saving VC space.

Supporting ATM Forum ProtocolsYou can connect the MPLS LSC to a network that is running ATM Forum protocols while the MPLS LSC simultaneously performs its functions. However, you must connect the ATM Forum network through a separate ATM interface (that is, not through the master control port).

MPLS Egress NetFlow AccountingMPLS egress NetFlow accounting allows you to capture IP flow information for packets undergoing MPLS label disposition; that is, packets that arrive on a router as MPLS and are sent as IP.

Previous to the MPLS Egress NetFlow Accounting feature, you captured NetFlow data only for flows that arrived on the packet in IP format. When an edge router performed MPLS label imposition (received an IP packet and sent it as an MPLS packet), NetFlow data was captured when the packet entered the network. Inside the network, the packet was switched based only on MPLS information, and thus NetFlow information was not captured until after the last label was removed.

One common application of the MPLS egress NetFlow accounting feature allows you to capture the MPLS VPN IP flows that are traveling from one site of a VPN to another site of the same VPN through the service provider backbone.

Previous to the MPLS Egress NetFlow Accounting feature, you captured flows only for IP packets on the ingress interface of a router. You could not capture flows for MPLS encapsulated frames, which were switched through CEF from the input port. Therefore, in an MPLS VPN environment you captured flow information as packets were received from a CE router and forwarded to the backbone. However, you could not capture flow information as packets were sent to a CE router because those packets were received as MPLS frames.

The MPLS egress NetFlow accounting feature lets you capture the flows on the outgoing interfaces.

Figure 50 shows a sample topology. To capture the flow of traffic going to Site 2 of VPN 1 from any remote VPN 1 sites, you enable MPLS egress NetFlow accounting on link PE2-CE5 of provider edge router PE2. The flows are stored in a global flow cache maintained by the router. You can use the show ip cache flow EXEC command or other aggregation flow commands to view the egress flow data.

Multiprotocol Label Switching OverviewMPLS Egress NetFlow Accounting


Figure 50 Provider and Customer Networks with MPLS Egress NetFlow Accounting

The PE routers export the captured flows to the configured collector devices in the provider network. The NetFlow Analyzer or the VPN solution center (VPN-SC) application collects this information and computes and displays site-to-site VPN traffic statistics.

Benefits to MPLS Egress NetFlow Accounting are as follows:

• Enhanced network monitoring for complete billing solution—You can now capture flows on the egress and ingress router interfaces to provide complete end-to-end usage information on network traffic. The accounting server uses the collected data for various levels of aggregation for accounting reports and API accounting information, thus providing a complete billing solution.

• More accurate accounting statistics—NetFlow data statistics now account for all the packets that are dropped in the core of the service provider network, thus providing more accurate traffic statistics and patterns.

4294

9

PE3

PE2

CE2

CE5

C

CE4

PE4

P

CE3

CE1

P

PE1Collector 1

Collector 2

VPN-SC Backbone

Site 1VPN 1

Site 2VPN 2

Site 3VPN 1

Site 2VPN 1

Site 1VPN 2

CE6

Site 4VPN 1


Configuring Multiprotocol Label Switching

This chapter describes how to configure your network to perform Multiprotocol Label Switching (MPLS).

This chapter contains the following sections:

• Configuring MPLS Levels of Control

• Configuring a Router for MPLS Forwarding

• Configuring MPLS Traffic Engineering

• Configuring MPLS Traffic Engineering Paths

• Configuring MPLS Virtual Private Networks

• Configuring MPLS QoS Backbone Support

• Configuring MPLS QoS

• Configuring the MPLS Label Switch Controller

• Configuring MPLS Egress NetFlow Accounting

• Verifying Configuration of MPLS Forwarding

For configuration examples on MPLS, see the “MPLS Configuration Examples” section.



Configuring MPLS Levels of ControlThis section describes three sample cases where MPLS is configured on Cisco 7500 and 7200 series routers. These cases show the levels of control possible in selecting how MPLS is deployed in a network.

Configuring Multiprotocol Label SwitchingConfiguring MPLS Levels of Control


Table 28 lists the cases, including the steps to perform MPLS and their corresponding Cisco IOS CLI commands.

For more information about the Cisco IOS CLI commands, see the chapter “MPLS Commands” in the Cisco IOS Switching Services Command Reference.

Figure 51 shows a router-only MPLS network with Ethernet interfaces. The following sections outline the procedures for configuring MPLS and displaying MPLS information in a network based on the topology shown in Figure 51.

Note Ethernet interfaces are shown in Figure 51, but any of the interfaces that are supported could be used instead. ATM interfaces operating as TC-ATM interfaces are the exception to this statement.

Figure 51 A Router-Only MPLS Network with Ethernet Interfaces

Table 28 MPLS—Levels of Control

Levels of Control Examples Description

Case 1—Enable MPLS Incrementally in a Network The steps necessary for incrementally deploying MPLS through a network, assuming that packets to all destination prefixes should be label switched.

Case 2—Route Labeled Packets to Network A Only The mechanism by which MPLS can be restricted, such that packets are label switched to only a subset of destinations.

Case 3—Limit Label Distribution on an MPLS Network

The mechanisms for further controlling the distribution of labels within a network.

Network A

Network B

S59

18

R1

R2 R5 R8

R4 R 7

e0/1

e0/1

e0/1

e0/1

e0/2

e0/2

e0/2

e0/2

e0/1

e0/1

e0/1 e0/2

R6R3

e0/4 e0/3

e0/1

e0/4

e0/2e0/2

e0/2 e0/3



Case 1—Enable MPLS Incrementally in a NetworkIn the first case, assume that you want to deploy MPLS incrementally throughout a network of routers, but that you do not want to restrict which destination prefixes are label switched. For a description of the commands listed in these cases, see the chapter “MPLS Commands” in the Cisco IOS Switching Services Command Reference.

To enable MPLS incrementally in a network, use the following commands beginning in router configuration mode (see Figure 51):

After you perform these steps, R1 applies labels to packets that are forwarded through Ethernet interface e0/1, with a next hop to R3.

You can enable MPLS throughout the rest of the network by repeating steps 1 and 2 as appropriate on other routers until all routers and interfaces are enabled for MPLS. See the example in the “Enabling MPLS Incrementally in a Network Example” section.

Command Purpose

Step 1 At R1:Router# configuration terminalRouter(config)# ip cef distributedRouter(config)# tag-switching advertise-tagsRouter(config)# interface e0/1Router(config-if)# tag-switching ipRouter(config-if)# exitAt R3:Router# configuration terminalRouter(config)# ip cef distributedRouter(config)# tag-switching advertise-tagsRouter(config)# interface e0/1Router(config-if)# tag-switching ip

Enables MPLS between R1 and R3.

In order to configure distributed VIP MPLS, you must configure dCEF switching. Enter the ip cef distributed global configuration command on all routers.

Step 2 At R3:Router(config)# interface e0/2Router(config-if)# tag-switching ipRouter(config-if)# exitAt R4:Router# configuration terminalRouter(config)# ip cef distributedRouter(config)# tag-switching advertise-tagsRouter(config)# interface e0/2Router(config-if)# tag-switching ipRouter(config-if)# exit

Enables MPLS between R3 and R4.



Case 2—Route Labeled Packets to Network A OnlyIn the second case, assume that you want to enable MPLS for a subset of destination prefixes. This option might be used to test MPLS across a large network. In this case, you would configure the system so that only a small number of destinations is label switched (for example, internal test networks) without the majority of traffic being affected.

To enable MPLS for a subset of destination prefixes, use the following commands at each router in the network in router configuration mode (see Figure 51):

Case 3—Limit Label Distribution on an MPLS NetworkThe third case demonstrates the full control available to you in determining the destination prefixes and paths for which MPLS is enabled.

Configure the routers so that packets addressed to network A are labeled, all other packets are unlabeled, and only links R1-R3, R3-R4, R4-R6, and R6-R7 carry labeled packets addressed to network A. For example, suppose the normally routed path for packets arriving at R1 addressed to network A or network B is R1, R3, R5, R6, R7. A packet addressed to network A would flow labeled on links R1-R3 and R6-R7, and unlabeled on links R3-R5 and R5-R6. A packet addressed to network B would follow the same path, but would be unlabeled on all links.

Assume that at the outset the routers are configured so that packets addressed to network A are labeled and all other packets are unlabeled (as at the completion of Case 2).

Use the tag-switching advertise-tags command and access lists to limit label distribution. Specifically, you need to configure routers R2, R5, and R8 to distribute no labels to other routers. This ensures that no other routers send labeled packets to any of those three. You also need to configure routers R1, R3, R4, R6, and R7 to distribute labels only for network A and to distribute them only to the appropriate adjacent router; that is, R3 distributes its label for network A only to R1, R4 only to R3, and so on.

To limit label distribution on a MPLS network, use the following commands in router configuration mode:

Command Purpose

Step 1 Router(config)# access-list 1 permit A Limits label distribution by using an access list.

(Enter the actual network address and netmask in place of permit A. For example,

access-list 1 permit 192.5.34. 0 0.0.0.255.)

Step 2 Router(config)# tag-switching advertise-tags for 1 Instructs the router to advertise for network A only to all adjacent label switch routers.

Any labels for other destination networks that the router may have distributed before this step are withdrawn.

Command Purpose

Step 1 Router(config)# no tag-switching advertise-tags Configures R2 to distribute no labels.

Step 2 Router(config)# no tag-switching advertise-tags Configures R5 to distribute no labels.

Configuring Multiprotocol Label SwitchingConfiguring a Router for MPLS Forwarding


Configuring a Router for MPLS ForwardingMPLS forwarding on routers requires that CEF be enabled. To enable CEF on a router, enter the following commands:

Router# configure terminalRouter(config)# ip cef [distributed]

Note For best MPLS forwarding performance, use the distributed option on routers that support this option.

For more information on the CEF commands, refer to the Cisco IOS Switching Services Command Reference.

Step 3 Router(config)# no tag-switching advertise-tags Configures R8 to distribute no labels

Step 4 Router(config)# access-list 2 permit R1Router(config)# no tag-switching advertise-tags for 1Router(config)# tag-switching advertise-tags for 1 to 2Router(config)# exit

Configures R3 by defining an access list and by instructing the router to distribute labels for the networks permitted by access list 1 (created as part of case 2) to the routers permitted by access list 2.

The access list 2 permit R1 command permits R1 and denies all other routers.

(Enter the actual network address and netmask in place of permit R1. For example, access-list 1 permit 192.5.34.0 0.0.0.255.)

Step 5 Router(config)# access-list 1 permit ARouter(config)# access-list 2 permit R1Router(config)# tag-switching advertise-tags for 1 to 2Router(config)# exit

Configures R3.



Configures R4.



Configures R6.



Configures R7.


Command Purpose

Configuring Multiprotocol Label SwitchingConfiguring MPLS Traffic Engineering


Configuring MPLS Traffic EngineeringPerform the following tasks before you enable MPLS traffic engineering:

• Turn on MPLS tunnels

• Turn on CEF

• Turn on IS-IS or OSPF

To configure MPLS traffic engineering, perform the tasks described in the following sections:

• Configuring a Device to Support Tunnels

• Configuring an Interface to Support RSVP-Based Tunnel Signalling and IGP Flooding

• Configuring IS-IS for MPLS Traffic Engineering

• Configuring OSPF for MPLS Traffic Engineering

• Configuring an MPLS Traffic Engineering Tunnel

Configuring a Device to Support TunnelsTo configure a device to support tunnels, use the following commands in global configuration mode:

Command Purpose

Step 1 Router(config)# ip cef Enables standard CEF operation.

For information about CEF configuration and the command syntax, see the Cisco IOS Switching Services Command Reference.

Step 2 Router(config)# mpls traffic-eng tunnels Enables the MPLS traffic engineering tunnel feature on a device.



Configuring an Interface to Support RSVP-Based Tunnel Signalling and IGP Flooding

To configure an interface to support RSVP-based tunnel signalling and IGP flooding, use the following commands in interface configuration mode:

Note You must enable the tunnel feature on interfaces that you want to support MPLS traffic engineering.

Configuring IS-IS for MPLS Traffic EngineeringTo configure IS-IS for MPLS traffic engineering, perform the steps described below. For a description of the IS-IS commands (excluding the IS-IS traffic engineering commands), see the Cisco IOS IP and IP Routing Command Reference.

Command Purpose

Step 1 Router(config-if)# mpls traffic-eng tunnels Enables MPLS traffic engineering tunnels on an interface.

Step 2 Router(config-if)# ip rsvp bandwidth bandwidth Enables RSVP for IP on an interface and specifies the amount of bandwidth that will be reserved.

For a description of the ip rsvp interface command syntax, see the Cisco IOS Quality of Service Solutions Command Reference.

Command Purpose

Step 1 Router(config)# router isis Enables IS-IS routing and specifies an IS-IS process for IP. This command places the router in router configuration mode.

Step 2 Router(config-router)# mpls traffic-eng level-1

Turns on MPLS traffic engineering for IS-IS level 1.

Step 3 Router(config-router)# mpls traffic-eng router-id loopback0

Specifies that the traffic engineering router identifier for the node is the IP address associated with interface loopback0.

Step 4 Router(config-router)# metric-style wide

Configures a router to generate and accept only new-style TLVs.



Configuring OSPF for MPLS Traffic EngineeringTo configure OSPF for MPLS traffic engineering, use the following commands beginning in global configuration mode. For a description of the OSPF commands (excluding the OSPF traffic engineering commands), see the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols.

Configuring an MPLS Traffic Engineering TunnelTo configure an MPLS traffic engineering tunnel, use the following commands in interface configuration mode. This tunnel has two path setup options: a preferred explicit path and a backup dynamic path.

Command Purpose

Step 1 Router(config)# router ospf process-id Configures an OSPF routing process for IP and places the router in configuration mode.

The process-id argument is an internally used identification parameter for an OSPF routing process. It is locally assigned and can be any positive integer. Assign a unique value for each OSPF routing process.

Step 2 Router(config-router)# mpls traffic-engarea 0

Turns on MPLS traffic engineering for OSPF area 0.

Step 3 Router(config-router)# mpls traffic-engrouter-id loopback0

Specifies that the traffic engineering router identifier for the node is the IP address associated with interface loopback0.

Command Purpose

Step 1 Router(config)# interface tunnel Configures an interface type and enters interface configuration mode.

Step 2 Router(config)# ip unnumbered loopback0 Gives the tunnel interface an IP address.

An MPLS traffic engineering tunnel interface should be unnumbered because it represents a unidirectional link.

Step 3 Router(config-if)# tunnel destination A.B.C.D

Specifies the destination for a tunnel.

Step 4 Router(config-if)# tunnel mode mpls traffic-eng

Sets the tunnel encapsulation mode to MPLS traffic engineering.

Step 5 Router(config-if)# tunnel mpls traffic-eng bandwidth bandwidth

Configures the bandwidth for the MPLS traffic engineering tunnel.

Step 6 Router(config-if)# tunnel mpls traffic-engpath-option number {dynamic | explicit {name path-name | path-number}} [lockdown]

Configures the tunnel to use a named IP explicit path or a path dynamically calculated from the traffic engineering topology database. A dynamic path is used if an explicit path is unavailable.

Configuring Multiprotocol Label SwitchingConfiguring MPLS Traffic Engineering Paths


Configuring MPLS Traffic Engineering PathsTo configure an MPLS traffic engineering tunnel that an IGP can use, use the following commands in interface configuration mode:

Configuring MPLS Virtual Private NetworksTo configure and verify VPNs, perform the tasks described in the following sections:

• Defining VPNs

• Configuring BGP Routing Sessions

• Configuring PE to PE Routing Sessions

• Configuring BGP PE to CE Routing Sessions

• Configuring RIP PE to CE Routing Sessions

• Configuring Static Route PE to CE Routing Sessions

• Configuring MPLS VPNs with Cable Interfaces

• Configuring Interautonomous Systems for MPLS VPNs

• Verifying VPN Operation

Defining VPNsTo define VPN routing instances, use the following commands beginning in router configuration mode on the PE router:

Command Purpose

Step 1 Router(config-if)# interface tunnel1 Configures an interface type and enters interface configuration mode.

Step 2 Router(config-if)# tunnel mpls traffic-eng autoroute announce

Causes the IGP to use the tunnel in its enhanced SPF calculation.

Command Purpose

Step 1 Router(config)# ip vrf vrf-name Enters VRF configuration mode and defines the VPN routing instance by assigning a VRF name.

Step 2 Router(config-vrf)# rd route-distinguisher Creates routing and forwarding tables.

Step 3 Router(config-vrf)# route-target {import | export | both} route-target-ext-community

Creates a list of import or export route target communities for the specified VRF.

Step 4 Router(config-vrf)# import map route-map (Optional) Associates the specified route map with the VRF.

Step 5 Router(config-vrf)# export map route-map (Optional) Associates the specified export route map with the VRF.

Step 6 Router(config-if)# ip vrf forwarding vrf-name Associates a VRF with an interface or subinterface.

Configuring Multiprotocol Label SwitchingConfiguring MPLS Virtual Private Networks


Configuring BGP Routing SessionsTo configure BGP routing sessions in a provider network, use the following commands beginning in router configuration mode on the PE router:

Configuring PE to PE Routing SessionsTo configure PE to PE routing sessions in a provider network, use the following commands beginning in router configuration mode on the PE router:

Command Purpose

Step 1 Router(config)# router bgp autonomous-system Configures the BGP routing process with the autonomous system number passed along to other BGP routers.

Step 2 Router(config-router)# neighbor {ip-address | peer-group-name} remote-as number

Specifies a neighbor’s IP address or BGP peer group identifying it to the local autonomous system.

Step 3 Router(config-router)# neighbor ip-address activate Activates the advertisement of the IPv4 address family.

Command Purpose

Step 1 Router(config-router)# address-family vpnv4 [unicast | multicast]

Defines IBGP parameters for VPNv4 NLRI exchange.

Step 2 Router(config-router-af)# neighbor address remote-as as-number

Defines an IBGP session to exchange VPNv4 NLRIs.

Step 3 Router(config-router-af)# neighbor address activate Activates the advertisement of the IPv4 address family.



Configuring BGP PE to CE Routing SessionsTo configure BGP PE to CE routing sessions, use the following commands beginning in router configuration mode on the PE router:

Configuring RIP PE to CE Routing SessionsTo configure RIP PE to CE routing sessions, use the following commands beginning in router configuration mode on the PE router:

Command Purpose

Step 1 Router(config-router)# address-family ipv4 [unicast] vrf vrf-name

Defines EBGP parameters for PE to CE routing sessions.

Note The default is Off for autosummary and synchronization in the VRF address-family submode.

Step 2 Router(config-router-af)# neighbor address remote-as as-number

Defines an EBGP session between PE and CE routers.

Step 3 Router(config-router-af)# neighbor address activate Activates the advertisement of the IPv4 address family.

Command Purpose

Step 1 Router(config)# router rip Enables RIP.

Step 2 Router(config-router-af)# address-family ipv4 [unicast] vrf vrf-name

Defines RIP parameters for PE to CE routing sessions.

Note The default is Off for auto-summary and synchronization in the VRF address-family submode.

Step 3 Router(config-router-af)# network prefix Enables RIP on the PE to CE link.



Configuring Static Route PE to CE Routing SessionsTo configure static route PE to CE routing sessions, use the following commands in router configuration mode on the PE router:

Configuring MPLS VPNs with Cable InterfacesBefore configuring IP-based VPNs on Cisco uBR7200 series, perform the following tasks:

• Ensure that your network supports reliable broadband data transmission. Your network area must be swept, balanced, and certified based on National Television Standards Committee (NTSC) or appropriate international cable plant recommendations. Ensure that your network area meets all DOCSIS or European Data-over-Cable Service Interface Specifications (EuroDOCSIS) downstream and upstream RF requirements.

• Ensure that your Cisco uBR7200 series universal broadband router is installed following instructions in the Cisco uBR7200 Series Universal Broadband Router Hardware Installation Guide and the Regulatory Compliance and Safety Information for the Cisco uBR7200 Series Universal Broadband Router.

• Ensure that your Cisco uBR7200 series universal broadband router is configured for basic operations following instructions in the Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide. The chassis must contain at least one port adapter to provide backbone connectivity and one Cisco cable modem card to serve as the RF cable TV interface.

Command Purpose

Step 1 Router(config)# ip route vrf vrf-name Defines static route parameters for every PE to CE session.

Step 2 Router(config-router)# address-family ipv4 [unicast] vrf vrf-name

Defines static route parameters for every BGP PE to CE routing session.

Note The default is Off for auto-summary and synchronization in the VRF address-family submode.

Step 3 Router(config-router-af)# redistribute static Redistributes VRF static routes into the VRF BGP table.

Step 4 Router(config-router-af)# redistribute connected Redistributes directly connected networks into the VRF BGP table.



To configure MPLS VPNs with cable interfaces, perform the tasks described in the following sections. The first two sections are required tasks; the remaining tasks are optional:

• Creating VRFs for Each VPN (Required)

• Defining Subinterfaces on a Physical Cable Interface and Assigning VRFs (Required)

• Configuring Cable Interface Bundles (Optional)

• Configuring Subinterfaces and MPLS VPNs on a Bundle Master (Optional)

• Configuring MPLS in the P Routers in the Provider Core (Optional)

• Verifying the MPLS VPN Configuration (Optional)

Restrictions

The following restrictions apply to configuring MPLS VPNs with cable interfaces:

• Each subinterface on the CMTS requires an address range from the ISP and from the MSO. These two ranges must not overlap and must be extensible to support an increased number of subscribers for scalability. Cisco IOS Release 12.1(2)EC and 12.1(2)T do not support overlapping addresses for the MPLS VPN subinterface.

Note This document does not address allocation and management of MSO and ISP IP addresses. See Configuring Multiprotocol Label Switching for this information.

• Cisco IOS Release 12.1(2) T supports the cable source-verify dhcp cable interface command, but Cisco IOS Release 12.1(2)EC does not support it. The cable source-verify dhcp cable interface command enables Dynamic Host Control Protocol (DHCP) servers to verify IP addresses of upstream traffic, and prevent MSO users from using unauthorized, spoofed, or stolen IP addresses.

• When using only MPLS VPNs, create subinterfaces on the bundle master, assign them an IP address, and provide VRF configuration for each ISP. When you create subinterfaces and configure only MPLS VPNs, the cable interface bundling feature is independent of the MPLS VPN.

• When using cable interface bundling, perform the following tasks:

– Define one of the interfaces in the bundle as the bundle master interface.

– Specify all generic IP networking information (such as IP address, routing protocols, and switching modes) on the bundle master interface. Do not specify generic IP networking information on bundle slave interfaces. If you attempt to add an interface to a bundle as a nonmaster interface and an IP address is assigned to this interface, the command will fail. You must remove the IP address configuration before you can add the interface to a bundle.

– An interface that has a subinterfaces defined over it is not allowed to be a part of the bundle.

– Specify generic (not downstream or upstream related) cable interface configurations, such as source-verify or ARP handling, on the master interface. Do not specify generic configuration on nonmaster interfaces.

– If you configure an interface as a part of a bundle and it is not the master interface, all generic cable configuration for this interface is removed. The master interface configuration will then apply to all interfaces in the bundle.



• Cable interface bundling is only supported on cable interfaces. Cisco IOS software provides cable interfaces with Cisco uBR-MC11, Cisco uBR-MC12, Cisco uBR-MC14, and Cisco uBR-MC16 cable modem cards.

• Interface bundles can only be configured using the command-line interface (including the CLI-based HTML configuration).

Creating VRFs for Each VPN

To create VRFs for each VPN, use the following commands beginning in router configuration mode:

Note Because only the CMTS has logical subinterfaces, assignments of VRFs on the other PE devices will be to specific physical interfaces.

Command Purpose

Step 1 Router(config)# ip vrf mgmt-vpn Enters VRF configuration mode and maps a VRF table to the VPN (specified by mgmt-vpn argument). The management VPN is the first VPN configured.

Step 2 Router(config-vrf)# rd mgmt-rd Creates a routing and forwarding table by assigning a RD to the management VPN.

Step 3 Router(config-vrf)# route-target {export| import| both} mgmt-rd

Exports or imports all routes for the RD of the management VPN. This determines which routes will be shared within VRFs.

Step 4 Router(config-vrf)# route-target import isp1-vpn-rd Imports all routes for the VPNs (isp1-vpn argument) route distinguisher.

Step 5 Router(config-vrf)# route-target import isp2-vpn-rd Imports all routes for the VPNs (isp2-vpn argument) RD.

Step 6 Router(config-vrf)# ip vrf isp1-vpn Creates a routing and forwarding table by assigning a RD to isp1-vpn argument) .

Step 7 Router(config-vrf)# rd mgmt-rd Creates a routing and forwarding table by assigning a RD (mgmt-rd argument) to the management VPN (mgmt-vpn argument) .

Step 8 Router(config-vrf)# route-target export isp1-vpn-rd Exports all routes for the VPNs (isp1-vpn argument) RD.


Step 10 Router(config-vrf)# route-target import mgmt-vpn-rd Exports all routes for the VPNs (mgmt-vpn argument) RD.

Step 11 Router(config-vrf)# ip vrf isp2-vpn Creates a routing and forwarding table by assigning a RD to isp2-vpn argument) .

Step 12 Router(config-vrf)# route-target export isp2-vpn-rd Exports all routes for the VPNs (isp2-vpn argument) RD.


Step 14 Router(config-vrf)# route-target import mgmt-vpn-rd Imports all routes for the VPNs (mgmt-vpn argument) RD.



Defining Subinterfaces on a Physical Cable Interface and Assigning VRFs

To create a logical cable subinterface, use the following commands beginning in global configuration mode. Create one subinterface for each VPN (one per ISP). The first subinterface created must be configured as part of the management VPN (with the lowest subinterface number). Create VRFs using the procedure described in the “Creating VRFs for Each VPN” section and apply them to the subinterface.

Command Purpose

Step 1 Router# configure terminal Enters configuration mode.

Step 2 Router(config)# interface cable slot/port Enters cable interface configuration mode.

slot = slot number in chassis (slot numbers begin with a 0).

port = port number on cable modem card slot (port numbers begin with a 0).

Step 3 Router(config-if)# interface cable slot/port.n Defines the first (management) subinterface with the lowest subinterface number. Valid range for n is from 1 to 255.

Step 4 Router(config-subif)# description string Identifies the subinterface as the management subinterface.

Step 5 Router(config-subif)# ip vrf forwarding mgmt-vpn Assigns the subinterface to the management VPN (the MPLS VPN used by the MSO to supply service to customers).

Step 6 Router(config-subif)# ip address ipaddress mask Assigns the subinterface an IP address and a subnet mask.

Step 7 Router(config-subif)# cable helper-address ip-address cable-modem

Forwards DHCP requests from cable modems to the IP address listed.

Step 8 Router(config-subif)# cable helper-address ip-address host

Forwards DHCP requests from hosts to the IP address listed.

Step 9 Router(config-if)# interface cable slot/port.n Defines an additional subinterface for the ISP (such as isp1). Valid range for n is 1 to 255.

Step 10 Router(config-subif)# description string Identifies the subinterface (such as subinterface for the isp1-vpn argument).

Step 11 Router(config-subif)# ip vrf forwarding isp1-vpn Assigns the subinterface to isp1-vpn VPN.






Step 15 Router(config-if)# interface cable slot/port.n Defines an additional subinterface for the ISP (such as isp2). Valid range for n is 1 to 255.

Step 16 Router(config-subif)# description string Identifies the subinterface (such as subinterface for the isp2-vpn argument) .

Step 17 Router(config-subif)# ip vrf forwarding isp2-vpn Assigns the subinterface to isp2-vpn VPN.



Configuring Cable Interface Bundles

To assign a cable interface to a bundle, use the following commands beginning in global configuration mode:






Step 21 Router(config)# copy running-config startup-config Returns to configuration mode, and stores the configuration or changes to your startup configuration in NVRAM.

Note Use this command to save the configuration settings that you created in the Cisco uBR7200 series universal broadband router using the configuration mode, the setup facility, and AutoInstall. If you fail to do this, your configuration will be lost the next time you reload the router.

Step 22 Router(config)# exit Returns to configuration mode.

Command Purpose

Command Purpose

Step 1 Router(config)# interface cable slot/port Enters the cable interface configuration mode.

slot = slot number in chassis (slot numbers begin with 0).

port = port number on cable modem card slot (port numbers begin with 0).

IP addresses are not assigned to this interface. They are assigned to the logical subinterfaces created within this interface.

Step 2 Router(config-if)# cable bundle bundle-number master Defines the interface as the bundle’s master interface. Valid range for bundle-number argument is from 1 to 255.



Configuring Subinterfaces and MPLS VPNs on a Bundle Master

To configure subinterfaces on a bundle master and assign each subinterface a Layer 3 configuration, configure cable interface bundles using the procedure described in the “Configuring Cable Interface Bundles” section.

Define subinterfaces on the bundle master interface and assign a Layer 3 configuration to each subinterface using the procedure described in the “Defining Subinterfaces on a Physical Cable Interface and Assigning VRFs” section. Create one subinterface for each customer VPN (one per ISP).

Configuring MPLS in the P Routers in the Provider Core

To configure MPLS in the P routers in the provider core, use the following commands beginning in router configuration mode:

Step 3 Router(config)# interface cable slot/port Enters the cable interface configuration mode for another cable interface.

slot = slot number in chassis (slot numbers begin with 0).

port = port number on cable modem card slot (port numbers begin with 0).

IP addresses are not assigned to this interface. They are assigned to the logical subinterfaces created within this interface.

Step 4 Router(config-if)# cable bundle bundle-number Adds the interface to the bundle specified by bundle-number. Valid range for the bundle-number argument is from 1 to 255.

Command Purpose

Command Purpose

Step 1 Router(config)# ip cef Enables CEF operation.

Step 2 Router(config)# interface FastEthernet slot/port Enters FastEthernet interface configuration mode.

Step 3 Router(config-if)# ip address ip-address mask Defines the primary IP address range for the interface.

Step 4 Router(config-if)# mpls ip Enables the interface to be forwarded to an MPLS packet.

Step 5 Router(config-if)# mpls label-protocol ldp Enables Label Distribution Protocol (LDP) on the interface.



Verifying the MPLS VPN Configuration

To verify MPLS VPN operations on PE routers, use the following EXEC commands:

Configuring Interautonomous Systems for MPLS VPNsBefore you configure EBGP routing between autonomous systems or subautonomous systems in an MPLS VPN, ensure that you have properly configured all MPLS VPN routing instances and sessions. The configuration tasks outlined in this section build from those configuration tasks.

Perform the following tasks before you enable configure EBGP routing between autonomous systems or subautonomous systems in an MPLS VPN:

• Define VPN routing instances

• Configure BGP routing sessions in the service provider (P) network

• Configure PE to PE routing sessions in the service provider (P) network

• Configure BGP PE to CE routing sessions

Step 6 Router(config)# copy running-config startup-config Stores the configuration or changes to your startup configuration in NVRAM.

Note Use this command to save the configuration settings that you created in the Cisco uBR7200 series universal broadband router using the configuration mode, the setup facility, and AutoInstall. If you fail to do this, your configuration will be lost the next time you reload the router.

Step 7 Router(config)# exit Returns to the configuration mode.

Command Purpose

Command Purpose

Step 1 Router# show ip vrf Displays the set of VRFs and interfaces.

Step 2 Router# show ip route vrf Displays the IP routing table for a VRF.

Step 3 Router# show ip protocols vrf Displays the routing protocol information for a VRF.

Step 4 Router(config)# show cable bundle n forwarding-table Displays the forwarding table for the specified interface.



To configure the exchange of VPN-IPv4 addresses between two or more autonomous systems or subautonomous systems in a confederation, perform the tasks described in the following sections. The tasks in the following sections are described as required or optional:

• Configuring EBGP Routing for the Exchange of VPN Routes Between Autonomous Systems (Required)

• Configuring EBGP Routing for the Exchange of VPN Routes Between Subautonomous Systems in a Confederation (Required)

• Displaying VPN-IPv4 LFIB Entries (Optional)

Configuring EBGP Routing for the Exchange of VPN Routes Between Autonomous Systems

To configure an EBGP border edge router in an autonomous system to exchange VPN routes with another autonomous system, use the following commands beginning in global configuration mode:

Note Enter the redistribute connected subnets command in the IGP configuration portion of the router to propagates host routes for VPN-IPv4 EBGP neighbors to other routers and provider edge routers. Alternatively, you can specify the next-hop-self address when you configure IBGP neighbors.

Configuring EBGP Routing for the Exchange of VPN Routes Between Subautonomous Systems in a Confederation

In this confederation, subautonomous system IGP domains must know the addresses of CEBGP-1 and CEBGP-2. If you do not specify a next-hop-self address as part of the router configuration, ensure that the addresses of all PE routers in the subautonomous system are distributed throughout the network, not just the addresses of CEBGP-1 and CEBGP-2.

Command Purpose

Step 1 Router(config)# router bgp autonomous-system Creates an EBGP routing process and assigns it an AS number. The autonomous system number is passed along to identify the router to EBGP routers in another autonomous system.

Step 2 Router(config)# no bgp default route-target filter

Disables BGP route-target filtering. All received BGP VPN-IPv4 routes are accepted by the router.

Step 3 Router(config-router)# address-family vpnv4[unicast]

Configures a routing session to carry VPN-IPv4 addresses across the VPN backbone. Each address has been made globally unique by the addition of an 8-byte RD. Unicast is optional; use it if you need to specify a unicast prefix.

Step 4 Router(config-router-af)# neighbor peer-group-name remote-as autonomous-system

Enters the address-family submode and specifies a neighboring EBGP peer group. This EBGP peer group is identified to the specified autonomous system.

Step 5 Router(config-router-af)# neighbor peer-group-name activate

Activates the advertisement of the VPN-IPv4 address family to a neighboring EBGP router.

Step 6 Router(config-router-af)# exit-address-family Exits from the address-family submode of the global configuration mode.



Note To ensure that the host routes for VPN-IPv4 EBGP neighbors are propagated (by means of the IGP) to the other routers and provider edge routers, specify the redistribute connected router configuration command in the IGP configuration portion of the CEBGP router. If you are using OSPF, make sure that the OSPF process is not enabled on the CEBGP interface where the “redistribute connected” subnet exists.

To configure EBGP border edge router in a confederation to exchange VPN routes with another subautonomous system, use the following commands beginning in global configuration mode:

Command Purpose

Step 1 Router(config)# router bgp subautonomous-system Creates an EBGP routing process and assigns it an autonomous system number. The subautonomous system number is passed along to identify the router to EBGP routers in other subautonomous systems.

Step 2 Router(config)# bgp confederation identifier autonomous-system

Defines an EBGP confederation by specifying a confederation identifier associated with each subautonomous system. The subautonomous systems appear as a single autonomous system.

Step 3 Router(config)# bgp confederation peers subautonomous-systems

Specifies the subautonomous systems that belong to the confederation (identifying neighbors from other subautonomous systems within the confederation as special EBGP peers).

Step 4 Router(config)# no bgp default route-target filter

Disables BGP route-target community filtering. All received BGP VPN-IPv4 routes are accepted by the router.

Step 5 Router(config-router)# address-family vpnv4[unicast]

Configures a routing session to carry VPN-IPv4 addresses across the VPN backbone. Each address has been made globally unique by the addition of an 8-byte RD. Unicast is optional; use it if you need to specify a unicast prefix.

Step 6 Router(config-router-af)# neighbor peer-group-name remote-as autonomous-system

Enters the address-family submode and specifies a neighboring EBGP peer group. This EBGP peer group is identified to the specified subautonomous system.

Step 7 Router(config-router-af)# neighbor peer-group-name next-hop-self

Advertises the router as the next hop for the specified neighbor. If you specify a next-hop-self address as part of the router configuration, you need not use the redistribute connected router configuration command

Step 8 Router(config-router-af)# neighbor peer-group-name activate

Activates the advertisement of the VPN-IPv4 address family to a neighboring PE router in the specified subautonomous system.

Step 9 Router(config-router-af)# exit-address-family Exits from the address-family submode of the global configuration mode.



Displaying VPN-IPv4 LFIB Entries

To display the VPN-IPv4 Label Forwarding Information Base (LFIB) entries at the border edge routers in the autonomous systems, use the following EXEC commands:

The following is an example of how the VPN-IPv4 LFIB entries appear when you use the show tag-switching forwarding-table privileged EXEC command:

Router# show tag-switching forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop tag tag or VC or Tunnel Id switched interface 33 33 10.120.4.0/24 0 Hs0/0 point2point 35 27 100:12:10.200.0.1/32 \ 0 Hs0/0 point2point

Note In this example, the Prefix field appears as a VPN-IPv4 RD, plus the prefix. If the value is longer than the Prefix column (as illustrated in the last line of the example), the output automatically wraps onto the next line in the forwarding table to preserve column alignment.

Verifying VPN OperationTo verify VPN operation by displaying routing information on the PE routers, use the following show commands, as needed:

Command Purpose

Step 1 Router# show ip bgp vpnv4 all [tags] Displays information about all VPN-IPv4 labels.

Step 2 Router# show tag-switching forwarding-table Displays the contents of the LFIB (such as VPN-IPv4 prefix or length and BGP next hop destination for the route).

Command Purpose

Router# show ip vrf Displays the set of defined VRFs and interfaces.

Router# show ip vrf [{brief | detail | interfaces}] vrf-name Displays information about defined VRFs and associated interfaces.

Router# show ip route vrf vrf-name Displays the IP routing table for a VRF.

Router# show ip protocols vrf vrf-name Displays the routing protocol information for a VRF.

Router# show ip cef vrf vrf-name Displays the CEF forwarding table associated with a VRF.

Router# show ip interface interface-number Displays the VRF table associated with an interface.

Router# show ip bgp vpnv4 all [tags] Displays information about all BGP VPN-IPv4 prefixes.

Router# show tag-switching forwarding vrf vrf-name [prefix mask/length][detail]

Displays label forwarding entries that correspond to VRF routes advertised by this router.

Configuring Multiprotocol Label SwitchingConfiguring MPLS QoS Backbone Support


Configuring MPLS QoS Backbone SupportSeveral different methods exist for supporting QoS across an MPLS backbone, the choice depending on whether the core has label switch routers (LSRs) or ATM-LSRs. In each case, however, the QoS building blocks are the same: CAR, WRED, and WFQ.

Three configurations are described in this section:

• LSRs used at the core of the network backbone

• ATM-LSRs used at the core of the network backbone

• ATM switches without the MPLS feature enabled

LSRs LSRs at the core of the MPLS backbone are usually either Cisco 7200 and Cisco 7500 series routers running MPLS software. Packets are processed as follows:

1. IP packets enter into the edge of the MPLS network.

2. The edge LSRs invoke CAR to classify the IP packets and possibly set IP precedence. Alternatively, IP packets can be received with their IP precedence already set.

3. For each packet, the router performs a lookup on the IP address to determine the next hop LSR.

4. The appropriate label is placed on the packet with the IP Precedence bits copied into every label entry in the MPLS header.

5. The labeled packet is then forwarded to the appropriate output interface for processing.

6. The packets are differentiated by class. This is done according to drop probability (WRED) or according to bandwidth and delay (WFQ). In either case, LSRs enforce the defined differentiation by continuing to employ WRED or WFQ on each hop.

ATM-LSRs ATM-LSRs at the core implement the multiple label virtual circuit model (LVC). In the multiple LVC model, one label is assigned for each service class for each destination. The operation of the edge LSR is the same as that described previously for the LSR case, except that the output is an ATM interface. WRED is used to define service classes and determine discard policy during congestion.

In the multiple LVC model, however, class-based WFQ (CBWFQ) is used to define the amount of bandwidth available to each service class. Packets are scheduled by class during congestion. The ATM-LSRs participate in the differentiation of classes with WFQ and intelligently drop packets when congestion occurs. The mechanism for this discard activity is weighted early packet discard (WEPD).

Configuring Multiprotocol Label SwitchingConfiguring MPLS QoS Backbone Support


ATM Switches When the core network uses ATM switches and the edge of the network uses MPLS-enabled edge LSRs, the edge LSRs are interconnected through a mesh of ATM Forum PVCs (CBR, VBR, or UBR) over the ATM core switches. The edge LSRs invoke WFQ on a per-VC basis to provide differentiation based on the delay of each MPLS QoS multiplexed onto the ATM Forum PVC. Optionally, WRED can also be used on a per-VC basis to manage drop priority between classes when congestion occurs on the edge LSR.

Table 29 lists the MPLS QoS features supported on packet interfaces.

Table 30 lists the MPLS QoS features supported on ATM interfaces.

Table 29 MPLS QoS Features Supported on Packet Interfaces

MPLS QoS Packet Feature Cisco 7500 Series

Cisco 7200 Series

Cisco 4000 Series

Cisco 3600 Series

Cisco 2600 Series

Per-interface WRED X X X X Untested

Per-interface, per-flow WFQ

X X X X Untested

Per-interface, per-class WFQ

X X X X Untested

Table 30 MPLS QoS Features Supported on ATM Interfaces

MPLS QoS ATM Forum PVCs Feature

Cisco 7500 Series

Cisco 7200 Series

Cisco 4000Series

Cisco 3600 Series

Cisco 2600 Series

Per-VC WRED X1

1. This feature is only available on the PA-A3.

X1 — — —

Per-VC WRED andper VC, per-class WFQ

— X1 — — —

MPLS QoS Multi-VC or LBR Feature

Per-interface WRED X2

2. This feature is only available on the PA-A1.

X2 — — —

Per-interface, per-class WFQ

X2 X2 — — —

Configuring Multiprotocol Label SwitchingConfiguring MPLS QoS


Table 31 lists the MPLS QoS features supported on ATM switches.

Configuring MPLS QoSPerform the following tasks before you enable MPLS traffic engineering:

• Turn on MPLS tunnels

• Turn on CEF

To configure MPLS QoS, perform the tasks described in the following sections. The first five sections are described as required; the remaining tasks are optional:

• Configuring QoS (Required)

• Setting the MPLS Experimental Field Value (Required)

• Using the Modular QoS CLI to Configure the Ingress Label Switching Router (Required)

• Using CAR to Configure the Ingress Label Switching Router (Required)

• Configuring the Output IP QoS of the Packet (Required)

• Configuring PVC Mode in a Non-MPLS-Enabled Core (Optional)

• Configuring Multi-VC Mode in a MPLS-Enabled Core (Optional)

• Configuring Multi-VCs Using the Cos-Map Function (Optional)

• Configuring DWFQ and Changing Queue Weights on an Outgoing Interface (Optional)

• Verifying QoS Operation (Optional)

Configuring QoSTo configure QoS, you can configure one or more of the following features (in addition, of course, to other items not described in this document):

• CAR

• WRED

• WFQ

Table 31 MPLS QoS Features Supported on ATM Switches

MPLS QoS ATM Forum PVCs Feature

BPX 8650 Series

MGX 8800 Series

LightStream 1010 ATM Switch1

Catalyst 8540 MSR1

1. This switch can be used for the core only.

MPLS QoS ATM Forum PVCs

X X X X

MPLS QoS Multi-VC or LBR—per-class WFQ

X — — —



Setting the MPLS Experimental Field ValueSetting the MPLS experimental field value satisfies the requirement of service providers that do not want the value of the IP Precedence field modified within IP packets transported through their networks.

By choosing different values for the MPLS experimental field, you can mark packets based on their characteristics, such as rate or type, so that packets have the priority that they require during periods of congestion.

Figure 52 shows a MPLS network of a service provider that connects two sites of a network belonging to a customer.

Figure 52 MPLS Network Connecting Two Sites of a Customer’s IP Network

To use these features in a network, set the MPLS experimental field value at PE1 (the ingress label switching router) by using the modular QoS CLI or the rate-limit interface command that CAR provides to set the QoS value in the MPLS packet. For detailed instructions, see the “Setting the MPLS Experimental Field Value” section.

Importance of Prioritizing a Packet Appropriately

During Step 1 of the configuration process (described in the “Using the Modular QoS CLI to Configure the Ingress Label Switching Router” and “Using CAR to Configure the Ingress Label Switching Router” sections) you classify IP packets according to their source address, destination address, port, protocol identification, or quality of service field. For example, packets can be identified based on one or more of the specified fields, as Voice over IP (VoIP) or a File Transfer Protocol (FTP). Packet classification/marking is important because a priority of a packet is determined by how it is classified or marked.

A priority of a packet affects how the packet is treated during periods of congestion. For example, service providers have service level agreements (SLAs) with customers. The agreement specifies how much traffic the service provider has agreed to deliver. To comply with the agreement, the customer must not send more than the agreed-upon rate. Packets are considered to be in-rate or out-of-rate. If there is congestion in the network, out-of-rate packets might be dropped more aggressively.

CE1

4186

7

PE1 P1 P2 PE2 CE2

IPnetwork

MPLSnetwork

IPnetwork

MPLSnetwork

Host A Host B

Owned byservice provider



Configuring the Ingress MPLS RouterTo classify IP packets, you configure the ingress label switching router. Packets are received at the ingress router as IP packets and sent as MPLS packets. To perform the configuration, use either of the following features:

• Modular QoS CLI, the newer and more flexible method—Use this method if you do not want to consider the rate of the packets that PE1 receives.

• CAR—Use if you want to consider the rate of the incoming packets:

– If a packet conforms to the SLA between the service provider and the customer (that is, the packet is in-rate), the service provider gives the packet preferential treatment when the network of a service provider is congested.

– If a packet does not conform (that is, it is out-of-rate) and the network is congested, the service provider might discard the packet or give it less preferential treatment.

Using the Modular QoS CLI to Configure the Ingress Label Switching RouterTo use the modular QoS CLI to configure PE1 (the ingress label switching router), perform the following steps:

Step 1 Configure a class map to classify IP packets according to their IP precedence.

Step 2 Configure a policy map to mark MPLS packets. (Write their classification into the MPLS experimental field.)

Step 3 Configure the input interface to attach the service policy.

Configuring a Class Map to Classify IP Packets

To configure a class map, use the following commands beginning in global configuration mode:

In the following example, all packets that contain IP Precedence 4 are matched by the class-map name IP_prec4:

Router(config)# class-map IP_prec4Router(config-c-map)# match ip precedence 4Router(config-c-map)# end

Command Purpose

Step 1 Router(config)# class-map class-map name Specifies the class map to which packets will be matched.

Step 2 Router(config-c-map)# match criteria Specifies the packet characteristics that will be matched to the class.

Step 3 Router(config-c-map)# end Exits class-map configuration mode.



Configuring a Policy Map to Set the MPLS Experimental Field

To configure a policy map, use the following commands beginning in global configuration mode:

In the following example, the value in the MPLS experimental field of each packet that is matched by the class-map IP_prec4 is set to 5:

Router(config)# policy-map set_experimental_5Router(config-p-map)# class IP_prec4Router(config-p-map-c)# set mpls experimental 5Router(config-p-map-c)# end

Configuring the Input Interface to Attach the Service Policy

To configure the input interface, use the following commands beginning in global configuration mode:

In the following example, the service policy set_experimental_5 is attached to an Ethernet input interface:

Router(config)# interface ethernet 1/0/0Router(config-int)# service-policy input set_experimental_5Router(config-int)# end

Using CAR to Configure the Ingress Label Switching Router To use CAR to configure the ingress label switching router, perform the following steps:

Step 1 Configure an IP rate-limit access list for classifying IP packets according to their IP precedence. Perform this step at PE1 (the ingress LSR).

Step 2 Configure a rate limit on an input interface to set MPLS packets. (Write the classification of the packet into the MPLS experimental field.)

Command Purpose

Step 1 Router(config)# policy-map policy-map name Creates a policy map that can be attached to one or more interfaces to specify a service policy.

Step 2 Router(config-p-map)# class class-map name Specifies the name of the class map previously designated in the class-map command.

Step 3 Router(config-p-map-c)# set mpls experimental value Designates the value to which the MPLS bits are set if the packets match the specified policy map.

Step 4 Router(config-p-map-c)# end Exits policy-map configuration mode.

Command Purpose

Step 1 Router(config)# interface name Designates the input interface.

Step 2 Router(config-int)# service-policy input policy-map name

Attaches the specified policy map to the input interface.

Step 3 Router(config-int)# end Exits interface configuration mode.



These steps are explained in the following sections.

Configuring a Rate Limit Access List for Classifying IP Packets

To configure a rate limit access list, use the following commands beginning in global configuration mode:

In the following example, all packets that contain IP Precedence 4 are matched by the rate-limit access list 24:

Router(config)# access-list rate-limit 24 4Router(config)# end

Configuring a Rate-Limit on an Input Interface to Set MPLS Packets

To configure a rate-limit on an input interface, use the following commands beginning in global configuration mode:

In the following example, the experimental field for the output MPLS packet is set to 4 if the input IP packets match the access list and conform to the rate. The MPLS experimental field is set to 0 if packets match access list 24 and exceed the input rate.

Router(config)# interface ethernet 1/0/0Router(config-int)# rate-limit input access-group rate-limit 24 8000 8000 8000 conform-action set-mpls-exp-transmit 4 exceed-action set-mpls-exp-transmit 0

Configuring the Output IP QoS of the PacketThe output QoS of the packet is determined by the IP header information. For configuration details, refer to the Cisco IOS Quality of Service Solutions Configuration Guide.

Command Purpose

Step 1 Router(config)# access-list rate-limit acl-index precedence

Specifies the criteria to be matched.

Step 2 Router(config)# end Exits configuration mode.

Command Purpose

Step 1 Router(config)# interface name Designates the input interface.

Step 2 Router(config-int)# rate-limit input [access-group [rate-limit]acl-index] bps burst-normal burst-max conform-action set-mpls-exp-transmit exp exceed-action set-mpls-exp-transmit exp

Specifies the action to take on packets during label imposition.



Configuring PVC Mode in a Non-MPLS-Enabled CoreTo configure a PVC in a non-MPLS-enabled core, use the following commands beginning in router configuration mode:

Configuring Multi-VC Mode in a MPLS-Enabled CoreTo configure multi-VC mode in an MPLS-enabled core, use the following commands beginning in router configuration mode:

Note The default for the multi-VC mode creates four VCs for each MPLS destination.

Command Purpose

Step 1 Router(config)# interface type number point-to-point Configures a point-to-point ATM subinterface.

Step 2 Router(config-subif)# ip unnumbered Loopback0 Assigns an IP address to the subinterface.

Step 3 Router(config-subif)# pvc 4/40 Creates a PVC on the subinterface.

Step 4 Router(config-if-atm-vc)# random-detect attach groupname

Activates WRED or dWRED on the interface.

Step 5 Router(config-if-atm-vc)# encapsulation aal5snap Sets encapsulation type for the PVC.

Step 6 Router(config-subif)# exit Exits from PVC mode and enters subinterface mode.

Step 7 Router(config-subif)# tag-switching ip Enables MPLS IP on the point-to-point interface.

Command Purpose

Step 1 Router(config)# interface type number tag-switching Configures an ATM MPLS subinterface.

Step 2 Router(config-subif)# ip unnumbered Loopback0 Assigns an IP address to the subinterface.

Step 3 Router(config-subif)# tag-switching atm multi-vc Enables ATM multi-VC mode on the subinterface.

Step 4 Router(config-subif)# tag-switching ip Enables MPLS on the ATM subinterface.



Configuring Multi-VCs Using the Cos-Map FunctionIf you do not choose to use the default for configuring label VCs, you can configure fewer label VCs by using the QoS map function. To use the QoS map function, use the following commands beginning in router configuration mode:

Configuring DWFQ and Changing Queue Weights on an Outgoing InterfaceTo configure distributed WFQ (dWFQ) and change queue weights on an interface, use the following commands in interface configuration mode after specifying the interface:

Command Purpose

Step 1 Router(config)# tag-switching cos-map cos-map number Creates a QoS map.

Step 2 Router(config-tag-cos-map)# class 1 premium Enters the cos-map submode and maps premium and standard classes to label VCs.

This QoS map assigns class 1 traffic to share the same label VC as class 2 traffic. The numbers you assign to the QoS map range from 0 to 3.

The defaults are:

• class 0 is available

• class 1 is standard

• class 2 is premium

• class 3 is control

Step 3 Router(config-tag-cos-map)# exit Exits the MPLS QoS map submode.

Step 4 Router(config)# access-list access-list-number permit destination

Creates an access list.

The access list acts on traffic going to the specified destination address.

Step 5 Router(config)# tag-switching prefix-map prefix-map access-list access-list cos-map cos-map

Configures the router to use a specified QoS map when an MPLS destination prefix matches the specified access list.

Command Purpose

Step 1 Router(config)# interface type number Specifies the interface type and number.

Step 2 Router(config-if)# fair-queue tos Configures an interface to use fair queueing.

Step 3 Router(config)# fair-queue tos class weight Changes the class weight on the specified interface.

Configuring Multiprotocol Label SwitchingConfiguring the MPLS Label Switch Controller


Verifying QoS OperationTo verify the operation of MPLS QoS, use the following EXEC commands:

Configuring the MPLS Label Switch ControllerTo enable MPLS LSC functionality, perform the tasks described in the following sections. The first two sections are required tasks; the remaining task is optional:

• Configuring MPLS on the Cisco 7200 Series LSCs for BPX and IGX Switches (Required)

• Configuring the Cisco 6400 UAC LSC (Required)

• Verifying MPLS LSC Configuration (Optional)

Refer to the Cisco BPX 8600 or IGX 8400 series documentation for BPX or IGX service node configuration examples.

Configuring MPLS on the Cisco 7200 Series LSCs for BPX and IGX SwitchesTo configure MPLS on the Cisco 7200 Series LSCs for BPX and IGX switches, use the following commands on each LSC in the configuration beginning in router configuration mode.

Note If you are configuring for LSC redundancy, ensure that the controller ID matches the slave and is unique to the LSC system. Also, make sure that the VPI/VC value for the control VC matches its peer.

Command Purpose

Step 1 Router# show tag-switching interfaces interfaces Displays detailed information about label switching interfaces.

Step 2 Router# show tag-switching cos-map Displays the QoS map used to assign VCs.

Step 3 Router# show tag-switching prefix-map Displays the prefix map used to assign a QoS map to network prefixes.

Command Purpose

Step 1 Router(config)# interface loopback0Router(config-if)# ip address 192.103.210.5 255.255.255.255

Enables a loopback interface. A loopback interface provides stable router and LDP identifiers.

Step 2 Router(config)# tag-switching atm disable-headend-vc Forces the LSC not to assign headend VCs for each destination prefix. With downstream on demand, MPLS ATM networks LVCs are a limited resource that are easily depleted with the addition of each new node.



Configuring the Cisco 6400 UAC LSC To configure a Cisco 6400 UAC LSC, perform the tasks in the following sections. The first section contains a required task; the remaining task is optional:

• Configuring Cisco 6400 UAC NRP as an MPLS LSC (Required)

• Configuring the Cisco 6400 UAC NSP for MPLS Connectivity to BPX (Optional)

Step 3 Router(config)# interface atm1/0Router(config-if)# tag-control-protocol vsi id 1

Enables the VSI protocol on the control interface ATM1/0 with controller ID 1. (Use a unique ID for each LSC.)

For the IGX, use the tag-control-protocol vsi slaves 32 id 1 command.

Step 4 Router(config-if)# interface XTagATM61Router(config-if)# extended-port atm1/0 bpx 6.1

Configures MPLS on the extended label ATM interface by creating an extended label ATM (XTagATM) virtual interface and binding it to BPX port 6.1.

For the IGX, use the extended-port atm1/0 descriptor 0.6.1.0 command.

Step 5 Router(config-if)# ip unnumbered loopback0Router(config-if)# tag-switching atm vpi 2-5Router(config-if)# tag-switching ip Router(config-if)# exit

Configures MPLS on the extended label ATM interface.

Limit the range so that the total number of VPIs does not exceed 4. For example:tag-switching atm vpi 2-5tag-switching atm vpi 10-13

Step 6 Router(config-if)# interface XTagATM1222Router(config-if)# extended-port atm1/0 bpx 12.2.2

Configures MPLS on another extended label ATM interface by creating an extended label ATM (XTagATM) virtual interface and binding it to BPX virtual trunk interface 12.2.2.

For the IGX, use the extended-port atm1/0 descriptor 0.12.2.2 command.

Step 7 Router(config-if)# ip unnumbered loopback0Router(config-if)# tag-switching atm vp-tunnel 2Router(config-if)# tag-switching ip Router(config-if)# exit

Configures MPLS on the extended label ATM interface using a VP-tunnel interface.

This will limit the VPI to only vpi = 2. The command will also map tag atm control vc to 2,32.

Step 8 Router(config)# ip cef Enables CEF switching.

Command Purpose



Configuring Cisco 6400 UAC NRP as an MPLS LSC

To configure a Cisco 6400 UAC NRP as an MPLS LSC, use the following commands beginning in global configuration mode:

Configuring the Cisco 6400 UAC NSP for MPLS Connectivity to BPX

To configure a Cisco 6400 UAC NSP for MPLS connectivity to BPX, use the following commands beginning in global configuration mode:

Command Purpose

Step 1 Router(config)# interface loopback0Router(config-if)# ip address 192.103.210.5 255.255.255.255

Enables a loopback interface. A loopback interface provides stable router and LDP identifiers.

Step 2 Router(config)# interface atm0/0/0Router(config-if)# tag-control-protocol vsi

Enables the VSI protocol on the control interface ATM0/0/0.


Configures MPLS on the extended label ATM interface by creating an extended label ATM (XTagATM) virtual interface and binding it to BPX port 6.1.



Limit the range so that the total number of VPIs does not exceed 4. For example:tag-switching atm vpi 2-5tag-switching atm vpi 10-13


Configures MPLS on the other extended label ATM interface by creating an extended label ATM (XTagATM) virtual interface and binding it to BPX port 12.2.



Limits the range so that the total number of VPIs does not exceed 4. For example:tag-switching atm vpi 2-5tag-switching atm vpi 10-13

Step 7 Router(config)# ip cef Enables CEF switching.

Step 8 Router(config)# tag-switching atm disable-headend-vc Disables headend VC label advertisement.

Command Purpose

Step 1 Switch# show hardware3/0 NRP 00-0000-00 .......

Displays the hardware connected to the Cisco 6400 UAC, including the position (3/0) of the NRP in the Cisco 6400 chassis.

Step 2 Switch(config)# interface atm3/0/0 Specifies the ATM interface for which you want to configure PVCs and PVPs.



Step 3 Switch(config-if)# atm pvc 0 40 interface ATM1/0/0 0 40 atm pvc 0 41 interface ATM1/0/0 0 41 atm pvc 0 42 interface ATM1/0/0 0 42 atm pvc 0 43 interface ATM1/0/0 0 43 atm pvc 0 44 interface ATM1/0/0 0 44 atm pvc 0 45 interface ATM1/0/0 0 45 atm pvc 0 46 interface ATM1/0/0 0 46 atm pvc 0 47 interface ATM1/0/0 0 47 atm pvc 0 48 interface ATM1/0/0 0 48 atm pvc 0 49 interface ATM1/0/0 0 49 atm pvc 0 50 interface ATM1/0/0 0 50 atm pvc 0 51 interface ATM1/0/0 0 51 atm pvc 0 52 interface ATM1/0/0 0 52 atm pvc 0 53 interface ATM1/0/0 0 53

Configures the PVC for the VSI control channel, depending on which of the 14 slots in the Cisco BPX is occupied by a Cisco BXM. If you do not know the BPX slots containing a BXM, configure all 14 PVCs to ensure that the NSP functions properly.

Note Do not enable MPLS on this interface.

However, if you know that Cisco BPX slots 10 and 12, for example, contain a BXM, you only need to configure PVCs corresponding to those slots, as follows:

atm pvc 0 49 interface ATM1/0/0 0 49 atm pvc 0 51 interface ATM1/0/0 0 51

Instead of configuring multiple PVCs, you can configure PVP 0 by deleting all well-known VCs. For example, you can use the atm manual-well-known-vc delete command on both interfaces and then configure PVP 0, as follows:

atm pvp 0 interface ATM1/0/0 0

Step 4 Switch(config-if)# atm pvp 2 interface ATM1/0/0 2 atm pvp 3 interface ATM1/0/0 3 atm pvp 4 interface ATM1/0/0 4 atm pvp 5 interface ATM1/0/0 5

Configures the PVPs for the LVCs. For XTagATM interfaces, use the VPI range 2 through 5 (by issuing a tag-switching atm vpi 2-5 command). If you want to use some other VPI range, configure the PVPs accordingly.

Command Purpose

Configuring Multiprotocol Label SwitchingConfiguring MPLS Egress NetFlow Accounting


Verifying MPLS LSC ConfigurationTo verify your MPLS LSC configuration, use the following commands in EXEC mode:

Configuring MPLS Egress NetFlow AccountingTo configure MPLS egress NetFlow, perform the tasks described in the following sections. The first section contains a required task; the remaining tasks are optional:

• Enabling MPLS Egress NetFlow Accounting (Required)

• Configuring NetFlow Aggregation Cache (Optional)

• Troubleshooting MPLS Egress NetFlow Accounting (Optional)

• Verifying MPLS Egress NetFlow Accounting Configuration (Optional)

• Monitoring and Maintaining MPLS Egress NetFlow Accounting (Optional)

Command Purpose

Step 1 Router# show controller vsi session Displays the VSI session state.

Step 2 Router# show tag-switching interfaces Displays the MPLS-enabled interface states.

Step 3 Router# show controllers vsi control-interface Displays information about an ATM interface that controls an external ATM switch or VSI control interface.

Step 4 Router# show interface XTagATM Displays information about an extended MPLS ATM interface.

Step 5 Router# show tag-switching tdp discovery Displays information about the discovery of MPLS neighbors.

Step 6 Router# show tag-switching tdp neighbor Displays information about the MPLS neighbor relationship.

Step 7 Router# show tag-switching atm capabilities Displays information about negotiated of TDP or LDP control VPs.

Step 8 Router# show tag-switching atm-tdp bindings Displays the current headend, tailend, and transit dynamic tag bindings for the destinations.

Step 9 Router# show tag-switching atm-tdp bindwait Displays the tag VCs that are in bindwait state along with their destinations.

Step 10 Router# show tag-switching atm summary Displays summary information about the number of destination networks discovered via routing protocol and the LVCs created on each extended label ATM interface.



Enabling MPLS Egress NetFlow AccountingTo enable MPLS egress NetFlow accounting, use the following command in interface configuration mode:

Configuring NetFlow Aggregation CacheTo configure NetFlow aggregation cache, use the following global configuration command:

Troubleshooting MPLS Egress NetFlow AccountingTo troubleshoot the MPLS egress NetFlow accounting feature, use the following commands in EXEC mode, as needed:

Command PurposeRouter(config-if)# mpls netflow egress Enables MPLS egress NetFlow accounting on the egress

router interface.

Command Purpose

Router(config)# ip flow-aggregation cache as | destination-prefix | prefix | protocol-port | source-prefix

Enters aggregation cache configuration mode and enables an aggregation cache scheme (as, destination-prefix, prefix, protocol-port, or source-prefix).

For more information on NetFlow aggregation, see the “Related Documents” section.

Command PurposeRouter# show mpls forwarding-table detail Displays detailed MPLS forwarding-table entries.

The output has been modified to show if MPLS egress NetFlow accounting is applied to packets destined to an entry. This is for debugging purposes only.

Router# show mpls interfaces internal all Displays detailed information about all of the MPLS interfaces in the router. The output has been modified to show if MPLS egress NetFlow accounting is enabled on the interface. This is for debugging purposes only.



Verifying MPLS Egress NetFlow Accounting ConfigurationTo verify MPLS egress NetFlow accounting configuration, perform the following steps:

Step 1 Enter the show ip cache flow EXEC command to display a summary of NetFlow switching statistics.

Note This is an existing command that displays ingress and egress NetFlow statistics.

Router# show ip cache flow

IP packet size distribution (10 total packets): 1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480 .000 .000 .000 1.00 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

512 544 576 1024 1536 2048 2560 3072 3584 4096 4608 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 4456704 bytes 1 active, 65535 inactive, 2 added 26 ager polls, 0 flow alloc failures last clearing of statistics neverProtocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)-------- Flows /Sec /Flow /Pkt /Sec /Flow /FlowICMP 1 0.0 5 100 0.0 0.0 15.7Total : 1 0.0 5 100 0.0 0.0 15.7

SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP PktsEt1/1 34.0.0.2 Et1/4 180.1.1.2 01 0000 0800 5

Table 32 describes the fields in the flow switching cache lines of the output.

Table 32 show ip cache flow Field Descriptions—Flow Switching Cache

Field Description

IP packet size distribution The two lines below this banner show the percentage distribution of packets by size range.

bytes Number of bytes of memory the NetFlow cache uses.

active Number of active flows in the NetFlow cache at the time this command is entered.

inactive Number of flow buffers that are allocated in the NetFlow cache but are not assigned to a specific flow at the time this command is entered.


ager polls Number of times the NetFlow code looked at the cache to remove expired entries (used by Cisco for diagnostics only).


last clearing of statistics Standard time output (hh:mm:ss) since the clear ip flow stats EXEC command was executed. This time output changes to hours and days after 24 hours is exceeded.



Table 33 describes the fields in the activity-by-protocol lines of the output.

Table 34 describes the fields in the current flow lines of the output.

Step 2 Enter the show ip cache flow aggregation EXEC command to display the contents of the aggregation cache. To display the prefix-based aggregation cache, use the following EXEC commands:

Table 33 show ip cache flow Field Descriptions—Activity-by-Protocol

Field Description

Protocol IP protocol and the “well known” port number as described in RFC 1340.

Total Flows Number of flows for this protocol since the last time statistics were cleared.

Flows/Sec Average number of flows for this protocol seen per second; equal to total flows/number of seconds for this summary period.

Packets/Flow Average number of packets observed for the flows seen for this protocol. Equal to total packets for this protocol/number of flows for this protocol for this summary period.

Bytes/Pkt Average number of bytes observed for the packets seen for this protocol (total bytes for this protocol and the total number of packet for this protocol for this summary period).

Packets/Sec Average number of packets for this protocol per second (total packets for this protocol and the total number of seconds for this summary period).

Active(Sec)/Flow Sum of all the seconds from the first packet to the last packet of an expired flow (for example, TCP FIN, time out, and so on) in seconds/total flows for this protocol for this summary period.

Idle(Sec)/Flow Sum of all the seconds from the last packet seen in each nonexpired flow for this protocol until the time this command was entered, in seconds/total flows for this protocol for this summary period.

Table 34 show ip cache flow Field Descriptions—Current Flow

Field Description

SrcIf Internal port name of the router for the source interface.

SrcIPaddress Source IP address for this flow.

DstIf Internal port name of the router for the destination interface.

DstIPaddress Destination IP address for this flow.

Pr IP protocol; for example, 6 = TCP, 17 = UDP, ... as defined in RFC 1340.

SrcP Source port address, TCP/UDP “well known” port number, as defined in RFC 1340.

DstP Destination port address, TCP/UDP “well known” port number, as defined in RFC 1340.

Pkts Number of packets that the router observed for this flow.



Router# show ip cache flow aggRouter# show ip cache flow aggregation prefRouter# show ip cache flow aggregation prefix

IP Flow Switching Cache, 278544 bytes 1 active, 4095 inactive, 1 added 4 ager polls, 0 flow alloc failures

Src If Src Prefix Msk Dst If Dst Prefix Msk Flows PktsEt1/1 34.0.0.0 /8 Et1/4 180.1.1.0 /24 1 5Router#

Table 35 describes the fields in the flow switching cache lines of the output.

Table 35 show ip cache flow aggregation prefix Field Descriptions—Flow Switching Cache

Field Description

bytes Number of bytes of memory the NetFlow cache uses.

active Number of active flows in the NetFlow cache at the time this command is entered.

inactive Number of flow buffers that are allocated in the NetFlow cache but are not assigned to a specific flow at the time this command is entered.


ager polls Number of times the NetFlow code looked at the cache to remove expired entries (used by Cisco for diagnostics only).




Table 36 describes the fields in the current flow lines of the output.

The ip flow-aggregation cache command has other options, including the following:

{as | destination-prefix | prefix | protocol-port | source-prefix}

Note For more information on these options, refer to the NetFlow Aggregation documentation.

Here is sample configuration output from the NetFlow aggregation cache:

Router(config)# ip flow-aggRouter(config)# ip flow-aggregation cacheRouter(config)# ip flow-aggregation cache ? as AS aggregation destination-prefix Destination Prefix aggregation prefix Prefix aggregation protocol-port Protocol and port aggregation source-prefix Source Prefix aggregation

Router(config)# ip flow-aggregation cache prefixRouter(config-flow-cache)# enable

Here is sample output displaying the IP aggregation cache contents:

Router# show ip cache flow aggregation ? as AS aggregation cache destination-prefix Destination Prefix aggregation cache prefix Source/Destination Prefix aggregation cache protocol-port Protocol and port aggregation cache source-prefix Source Prefix aggregation cacheRouter# show ip cache flowIP packet size distribution (206 total packets): 1-32 64 96 128 160 192 224 256 288 320 352 384 416 448 480 .000 .854 .000 .145 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

512 544 576 1024 1536 2048 2560 3072 3584 4096 4608 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000 .000

IP Flow Switching Cache, 4292920 bytes 0 active, 62977 inactive, 182 added 2912 ager polls, 0 flow alloc failures Active flows timeout in 30 minutes Inactive flows timeout in 15 seconds

Table 36 show ip cache flow aggregation prefix Field Descriptions—Current Flow

Field Description

Src If Router’s internal port name for the source interface.

Src Prefix Source IP address for this flow.

Msk Mask source.

Dst If Router's internal port name for the destination interface.

Dst Prefix Destination prefix aggregation cache scheme.

Msk Mask destination.

Flows Number of flows.

Pkts Number of packets that the router observed for this flow.

Configuring Multiprotocol Label SwitchingVerifying Configuration of MPLS Forwarding


last clearing of statistics neverProtocol Total Flows Packets Bytes Packets Active(Sec) Idle(Sec)-------- Flows /Sec /Flow /Pkt /Sec /Flow /FlowICMP 182 0.0 1 62 0.0 0.0 15.5Total : 182 0.0 1 62 0.0 0.0 15.5

SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts

Router# show ip cache flow aggregation prefix

IP Flow Switching Cache, 278544 bytes 1 active, 4095 inactive, 3 added 45 ager polls, 0 flow alloc failures Active flows timeout in 30 minutes Inactive flows timeout in 15 seconds

Src If Src Prefix Msk Dst If Dst Prefix Msk Flows PktsEt1/1 34.0.0.0 /8 PO6/0 12.12.12.12 /32 1 5Router#

Monitoring and Maintaining MPLS Egress NetFlow AccountingTo monitor and maintain MPLS egress NetFlow accounting, use the following command in EXEC mode:

Verifying Configuration of MPLS ForwardingTo verify that CEF has been configured properly, enter the show ip cef summary command, which generates output similar to the following:

Router# show ip cef summary

IP CEF with switching (Table Version 49), flags=0x0 43 routes, 0 resolve, 0 unresolved (0 old, 0 new) 43 leaves, 49 nodes, 56756 bytes, 45 inserts, 2 invalidations 2 load sharing elements, 672 bytes, 2 references 1 CEF resets, 4 revisions of existing leaves 4 in-place modifications refcounts: 7241 leaf, 7218 node

Adjacency Table has 18 adjacenciesRouter#

Command PurposeRouter# show ip cache flow Displays summary NetFlow switching statistics,

including the size of the packets, types of traffic, which interfaces the traffic enters and exits, and the source and destination addresses in the forwarded packet.

Configuring Multiprotocol Label SwitchingMPLS Configuration Examples


MPLS Configuration ExamplesThis section provides the following MPLS configuration examples:

• Enabling MPLS Incrementally in a Network Example

• Enabling MPLS for a Subset of Destination Prefixes Example

• Selecting the Destination Prefixes and Paths Example

• Displaying MPLS LDP Binding Information Example

• Displaying MPLS Forwarding Table Information Example

• Displaying MPLS Interface Information Example

• Displaying MPLS LDP Neighbor Information Example

• Enabling LSP Tunnel Signalling Example

• Configuring an LSP Tunnel Example

• Displaying the LSP Tunnel Information Example

• Configuring MPLS Traffic Engineering Examples

• Configuring MPLS VPNs Example

• Implementing MPLS QoS Example

• Configuring an MPLS LSC Examples

• MPLS Egress NetFlow Accounting Example

Enabling MPLS Incrementally in a Network ExampleThe following example shows how to configure MPLS incrementally throughout a network of routers. You enable MPLS first between one pair of routers (in this case, R1 and R3 shown in Figure 51) and add routers step by step until every router in the network is label switch enabled.

router-1# configuration terminalrouter-1(config)# ip cef distributedrouter-1(config)# tag-switching iprouter-1(config)# interface e0/1router-1(config-if)# tag-switching iprouter-1(config-if)# exitrouter-1(config)# router-3# configuration terminalrouter-3(config)# ip cef distributedrouter-3(config)# tag-switching iprouter-3(config)# interface e0/1router-3(config-if)# tag-switching iprouter-3(config-if)# exitrouter-3(config)#

Enabling MPLS for a Subset of Destination Prefixes ExampleThe following example shows the commands you enter at each of the routers to enable MPLS for only a subset of destination prefixes (see Figure 51).

Router(config)# access-list-1 permit ARouter(config)# tag-switching advertise-tags for 1



Selecting the Destination Prefixes and Paths ExampleThe following example shows the commands you enter to configure the routers to select the destination prefixes and paths for which MPLS is enabled. When you configure R2, R5, and R8 to distribute no labels to other routers, you ensure that no routers send them labeled packets. You also need to configure routers R1, R3, R4, R6, and R7 to distribute labels only for network A and only to the applicable adjacent router. This configuration ensures that R3 distributes its label for network A only to R1, R4 only to R3, R6 only to R4, and R7 only to R6 (see Figure 51).

router-2(config)# no tag-switching advertise-tagsrouter-5(config)# no tag-switching advertise-tagsrouter-8(config)# no tag-switching advertise-tagsrouter-1(config)# access-list permit R1router-1(config)# no tag-switching advertise-tags for 1router-1(config)# tag-switching advertise-tags for 1 to 2router-1(config)# exit

router-3# access-list 1 permit Arouter-3# access-list 2 permit R1router-3# tag-switching advertise-tags for 1 to 2router-3# exit

router-4# access-list 1 permit Arouter-4# access-list 2 permit R3router-4# tag-switching advertise-tags for 1 to 2router-4# exit

router-6# access-list 1 permit Arouter-6# access-list 2 permit R4router-6# tag-switching advertise-tags for 1 to 2router-6# exitrouter-7# access-list 1 permit Arouter-7# access-list 2 permit R6router-7# tag-switching advertise-tags for 1 to 2router-7# exit

Displaying MPLS LDP Binding Information ExampleThe following example shows how to use the show tag-switching tdp bindings EXEC command to display the contents of the Label Information Base (LIB). The display can show the entire database or can be limited to a subset of entries, based on prefix, input or output label values or ranges, or the neighbor advertising the label.

Note This command displays downstream mode bindings. For label VC bindings, see the show tag-switching atm-tdp bindings EXEC command.

Router# show tag-switching tdp bindings

Matching entries: tib entry: 10.92.0.0/16, rev 28 local binding: tag: imp-null(1) remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 10.102.0.0/16, rev 29 local binding: tag: 26 remote binding: tsr: 172.27.32.29:0, tag: 26 tib entry: 10.105.0.0/16, rev 30 local binding: tag: imp-null(1)



remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 10.205.0.0/16, rev 31 local binding: tag: imp-null(1) remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 10.211.0.7/32, rev 32 local binding: tag: 27 remote binding: tsr: 172.27.32.29:0, tag: 28 tib entry: 10.220.0.7/32, rev 33 local binding: tag: 28 remote binding: tsr: 172.27.32.29:0, tag: 29 tib entry: 99.101.0.0/16, rev 35 local binding: tag: imp-null(1) remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 100.101.0.0/16, rev 36 local binding: tag: 29 remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 171.69.204.0/24, rev 37 local binding: tag: imp-null(1) remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 172.27.32.0/22, rev 38 local binding: tag: imp-null(1) remote binding: tsr: 172.27.32.29:0, tag: imp-null(1) tib entry: 210.10.0.0/16, rev 39 local binding: tag: imp-null(1) tib entry: 210.10.0.8/32, rev 40 remote binding: tsr: 172.27.32.29:0, tag: 27

Displaying MPLS Forwarding Table Information ExampleThe following example shows how to use the show tag-switching forwarding-table command to display the contents of the LFIB. The LFIB lists the labels, output interface information, prefix or tunnel associated with the entry, and number of bytes received with each incoming label. A request can show the entire LFIB or can be limited to a subset of entries. A request can also be restricted to selected entries in any of the following ways:

• Single entry associated with a given incoming label

• Entries associated with a given output interface

• Entries associated with a given next hop

• Single entry associated with a given destination

• Single entry associated with a given tunnel having the current node as an intermediate hop

Router# show tag-switching forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop tag tag or VC or Tunnel Id switched interface 26 Untagged 10.253.0.0/16 0 Et4/0/0 172.27.32.4 28 1/33 10.15.0.0/16 0 AT0/0.1 point2point 29 Pop tag 10.91.0.0/16 0 Hs5/0 point2point 1/36 10.91.0.0/16 0 AT0/0.1 point2point 30 32 10.250.0.97/32 0 Et4/0/2 10.92.0.7 32 10.250.0.97/32 0 Hs5/0 point2point 34 26 10.77.0.0/24 0 Et4/0/2 10.92.0.7 26 10.77.0.0/24 0 Hs5/0 point2point 35 Untagged [T] 10.100.100.101/32 0 Tu301 point2point 36 Pop tag 168.1.0.0/16 0 Hs5/0 point2point 1/37 168.1.0.0/16 0 AT0/0.1 point2point



[T] Forwarding through a TSP tunnel. View additional tagging info with the 'detail' option

Displaying MPLS Interface Information ExampleThe following example shows how to use the show tag-switching interfaces command to show information about the requested interface or about all interfaces on which MPLS is enabled. The per-interface information includes the interface name and indications as to whether IP MPLS is enabled and operational.

Router# show tag-switching interfaces

Interface IP Tunnel OperationalHssi3/0 Yes Yes No ATM4/0.1 Yes Yes Yes (ATM tagging)Ethernet5/0/0 No Yes Yes Ethernet5/0/1 Yes No Yes Ethernet5/0/2 Yes No No Ethernet5/0/3 Yes No Yes Ethernet5/1/1 Yes No No

The following shows sample output from the show tag-switching interfaces command when you specify the detail keyword:

Router# show tag-switching interfaces detail

Interface Hssi3/0: IP tagging enabled TSP Tunnel tagging enabled Tagging not operational MTU = 4470Interface ATM4/0.1: IP tagging enabled TSP Tunnel tagging enabled Tagging operational MTU = 4470 ATM tagging: Tag VPI = 1, Control VC = 0/32Interface Ethernet5/0/0: IP tagging not enabled TSP Tunnel tagging enabled Tagging operational MTU = 1500Interface Ethernet5/0/1: IP tagging enabled TSP Tunnel tagging not enabled Tagging operational MTU = 1500Interface Ethernet5/0/2: IP tagging enabled TSP Tunnel tagging not enabled Tagging not operational MTU = 1500Interface Ethernet5/0/3: IP tagging enabled TSP Tunnel tagging not enabled Tagging operational MTU = 1500



Displaying MPLS LDP Neighbor Information ExampleThe following example shows how to use the show tag-switching tdp neighbors EXEC command to display the status of LDP sessions. The neighbor information branch can have information about all LDP neighbors or can be limited to the neighbor with a specific IP address or LDP identifier, or to LDP neighbors known to be accessible over a specific interface.

Router# show tag-switching tdp neighbors

Peer TDP Ident: 10.220.0.7:1; Local TDP Ident 172.27.32.29:1 TCP connection: 10.220.0.7.711 - 172.27.32.29.11029 State: Oper; PIEs sent/rcvd: 17477/17487; Downstream on demandUp time: 01:03:00TDP discovery sources: ATM0/0.1Peer TDP Ident: 210.10.0.8:0; Local TDP Ident 172.27.32.29:0 TCP connection: 210.10.0.8.11004 - 172.27.32.29.711 State: Oper; PIEs sent/rcvd: 14656/14675; Downstream;Up time: 2d5h TDP discovery sources: Ethernet4/0/1 Ethernet4/0/2 POS6/0/0 Addresses bound to peer TDP Ident: 99.101.0.8 172.27.32.28 10.105.0.8 10.92.0.8 10.205.0.8 210.10.0.8

Enabling LSP Tunnel Signalling ExampleThe following example shows how to configure support for LSP tunnel signalling along a path and on each interface crossed by one or more tunnels:

Router(config)# ip cef distributedRouter(config)# tag-switching tsp-tunnels Router(config)# interface e0/1Router(config-if)# tag-switching tsp-tunnelsRouter(config-if)# interface e0/2Router(config-if)# tag-switching tsp-tunnelsRouter(config-if)# exit

Configuring an LSP Tunnel ExampleThe following example shows how to set the encapsulation of the tunnel to MPLS and how to define hops in the path for the LSP.

Follow these steps to configure a two-hop tunnel, hop 0 being the headend router. For hops 1 and 2, you specify the IP addresses of the incoming interfaces for the tunnel. The tunnel interface number is arbitrary, but must be less than 65,535.

Router(config)# interface tunnel 2003Router(config-if)# tunnel mode tag-switchingRouter(config-if)# tunnel tsp-hop 1 10.10.0.12Router(config-if)# tunnel tsp-hop 2 10.50.0.24 lasthopRouter(config-if)# exit

To shorten the previous path, delete the hop by entering the following commands:

Router(config)# interface tunnel 2003Router(config-if)# no tunnel tsp-hop 2



Router(config-if)# tunnel tsp-hop 1 10.10.0.12 lasthopRouter(config-if)# exit

Displaying the LSP Tunnel Information ExampleThe following example shows how to use the show tag-switching tsp-tunnels command to display information about the configuration and status of selected tunnels:

Router# show tag-switching tsp-tunnels

Signalling Summary: TSP Tunnels Process: running RSVP Process: running Forwarding: enabled

TUNNEL ID DESTINATION STATUS CONNECTION10.106.0.6.200310.2.0.12up up

Configuring MPLS Traffic Engineering ExamplesThis section provides the following MPLS traffic engineering configuration examples:

• Configuring MPLS Traffic Engineering Using IS-IS Example

• Configuring MPLS Traffic Engineering Using OSPF Example

• Configuring an MPLS Traffic Engineering Tunnel Example

• Configuring Enhanced SPF Routing over a Tunnel Example

Figure 53 illustrates a sample MPLS topology. This example specifies point-to-point outgoing interfaces. The next sections contain sample configuration commands you enter to implement MPLS traffic engineering and the basic tunnel configuration shown in Figure 53.

Figure 53 Sample MPLS Traffic Engineering Tunnel Configuration

131.0.0Tunnel 1Router 1

11.11.11.11Router 2

15.15.15.15Router 4

14.14.14.14

Router 312.12.12.12

Router 517.17.17.17

2668

3

Tunn

el 2

135.

0.0

Tunnel 2

136.0.0

Tunnel 1 Tunnel 1.1 .2

S1/0 S1/2

S1/1

S1/3

S1/0

S1/1

.2 .1

.1 .2

S1/0 S1/0.1 .2

Tunnel 2133.0.0

S1/3 S1/0Tunnel 2



Configuring MPLS Traffic Engineering Using IS-IS Example

This example lists the commands you enter to configure MPLS traffic engineering with IS-IS routing enabled (see Figure 53).

Note You must enter the following commands on every router in the traffic-engineered portion of your network.

Router 1—MPLS Traffic Engineering Configuration

To configure MPLS traffic engineering, enter the following commands:

ip cefmpls traffic-eng tunnelsinterface loopback 0ip address 11.11.11.11 255.255.255.255ip router isis

interface s1/0ip address 131.0.0.1 255.255.0.0ip router isismpls traffic-eng tunnelsip rsvp bandwidth 1000

Router 1—IS-IS Configuration

To enable IS-IS routing, enter the following commands:

router isisnetwork 47.0000.0011.0011.00is-type level-1metric-style widempls traffic-eng router-id loopback0mpls traffic-eng level-1

Configuring MPLS Traffic Engineering Using OSPF Example

This example lists the commands you enter to configure MPLS traffic engineering with OSPF routing enabled (see Figure 53).

Note You must enter the following commands on every router in the traffic-engineered portion of your network.

Router 1—MPLS Traffic Engineering Configuration

To configure MPLS traffic engineering, enter the following commands:

ip cefmpls traffic-eng tunnelsinterface loopback 0ip address 11.11.11.11 255.255.255.255

interface s1/0ip address 131.0.0.1 255.255.0.0mpls traffic-eng tunnels ip rsvp bandwidth 1000



Router 1—OSPF Configuration

To enable OSPF, enter the following commands:

router ospf 0network 131.0.0.0.0.0.255.255 area 0mpls traffic-eng router-id Loopback0mpls traffic-eng area 0

Configuring an MPLS Traffic Engineering Tunnel Example

This example shows you how to configure a dynamic path tunnel and an explicit path in the tunnel. Before you configure MPLS traffic engineering tunnels, you must enter the appropriate global and interface commands on the specified router (in this case, Router 1).

Router 1—Dynamic Path Tunnel Configuration

In this section, a tunnel is configured to use a dynamic path:

interface tunnel1 ip unnumbered loopback 0 tunnel destination 17.17.17.17 tunnel mode mpls traffic-engtunnel mpls traffic-eng bandwidth 100 tunnel mpls traffic-eng priority 1 1 tunnel mpls traffic-eng path-option 1 dynamic

Router 1—Dynamic Path Tunnel Verification

This section includes the commands you use to verify that the tunnel is up:

show mpls traffic-eng tunnels show ip interface tunnel1

Router 1—Explicit Path Configuration

In this section, an explicit path is configured:

ip explicit-path identifier 1 next-address 131.0.0.1 next-address 135.0.0.1 next-address 136.0.0.1 next-address 133.0.0.1

Router 1—Explicit Path Tunnel Configuration

In this section, a tunnel is configured to use an explicit path:

interface tunnel2 ip unnumbered loopback 0 tunnel destination 17.17.17.17 tunnel mode mpls traffic-engtunnel mpls traffic-eng bandwidth 100 tunnel mpls traffic-eng priority 1 1 tunnel mpls traffic-eng path-option 1 explicit identifier 1



Router 1—Explicit Path Tunnel Verification

This section includes the commands you use to verify that the tunnel is up:

show mpls traffic-eng tunnels show ip interface tunnel2

Configuring Enhanced SPF Routing over a Tunnel Example

This section includes the commands that cause the tunnel to be considered by the enhanced SPF calculation of the IGP, which installs routes over the tunnel for appropriate network prefixes.

Router 1—IGP Enhanced SPF Consideration Configuration

In this section, you specify that the IGP should use the tunnel (if the tunnel is up) in its enhanced SPF calculation:

interface tunnel1tunnel mpls traffic-eng autoroute announce

Router 1—Route and Traffic Verification

This section includes the commands you use to verify that the tunnel is up and that the traffic is routed through the tunnel:

show traffic-eng tunnels tunnel1 briefshow ip route 17.17.17.17show mpls traffic-eng autorouteping 17.17.17.17show interface tunnel1 accountingshow interface s1/0 accounting

Configuring MPLS VPNs ExamplesThis section provides the following configuration examples:

• Configuring MPLS VPNs Example

• Defining a Cable Subinterface Example

• Cable Interface Bundling Example

• Subinterface Definition on Bundle Master Example

• Cable Interface Bundle Master Configuration Example

• Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems

• Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems in a Confederation

Configuring MPLS VPNs Example

The following example provides a sample configuration file from a PE router:

ip cef distributed ! CEF switching is pre-requisite for label Switchingframe-relay switching!ip vrf vrf1 ! Define VPN Routing instance vrf1



rd 100:1 route-target both 100:1 ! Configure import and export route-targets for vrf1!ip vrf vrf2 ! Define VPN Routing instance vrf2 rd 100:2 route-target both 100:2 ! Configure import and export route-targets for vrf2 route-target import 100:1 ! Configure an additional import route-target for vrf2 import map vrf2_import ! Configure import route-map for vrf2!interface lo0 ip address 10.13.0.13 255.255.255.255!interface atm9/0/0 ! Backbone link to another Provider router!interface atm9/0/0.1 tag-switching ip unnumbered loopback0no ip directed-broadcasttag-switching atm vpi 2-5 tag-switching ip

interface atm5/0no ip addressno ip directed-broadcast atm clock INTERNALno atm ilmi-keepalive

interface Ethernet1/0ip address 3.3.3.5 255.255.0.0no ip directed-broadcastno ip mroute-cacheno keepalive

interface Ethernet5/0/1 ! Set up Ethernet interface as VRF link to a CE router ip vrf forwarding vrf1 ip address 10.20.0.13 255.255.255.0 !interface hssi 10/1/0

hssi internal-clock encaps fr frame-relay intf-type dce frame-relay lmi-type ansi!interface hssi 10/1/0.16 point-to-point ip vrf forwarding vrf2 ip address 10.20.1.13 255.255.255.0 frame-relay interface-dlci 16 ! Set up Frame Relay PVC subinterface as link to another! ! CE router

router bgp 1 ! Configure BGP sessions no synchronization no bgp default ipv4-activate ! Deactivate default IPv4 advertisements neighbor 10.15.0.15 remote-as 1 ! Define IBGP session with another PE neighbor 10.15.0.15 update-source lo0! address-family vpnv4 unicast ! Activate PE exchange of VPNv4 NLRI neighbor 10.15.0.15 activate exit-address-family! address-family ipv4 unicast vrf vrf1 ! Define BGP PE-CE session for vrf1 redistribute static redistribute connected neighbor 10.20.0.60 remote-as 65535 neighbor 10.20.0.60 activate



no auto-summary exit-address-family! address-family ipv4 unicast vrf vrf2 ! Define BGP PE-CE session for vrf2 redistribute static redistribute connected neighbor 10.20.1.11 remote-as 65535 neighbor 10.20.1.11 update-source h10/1/0.16 neighbor 10.20.1.11 activate no auto-summary exit-address-family!! Define a VRF static routeip route vrf vrf1 12.0.0.0 255.0.0.0 e5/0/1 10.20.0.60!route-map vrf2_import permit 10 ! Define import route-map for vrf2. ...

Defining a Cable Subinterface Example

The following example shows how to define a subinterface on cable3/0:

interface cable3/0! No IP address! MAC level configuration only

! first subinterfaceinterface cable3/0.1description Management Subinterfaceip address 10.255.1.1 255.255.255.0cable helper-address 10.151.129.2

! second subinterfaceinterface cable3/0.2ip address 10.279.4.2 255.255.255.0cable helper-address 10.151.129.2

! third subinterfaceinterface cable3/0.3ip address 10.254.5.2 255.255.255.0cable helper-address 10.151.129.2

Cable Interface Bundling Example

The following example shows how to bundle a group of physical interfaces:

interface c3/0 and interface c4/0 are bundled.

interface c3/0ip address 209.165.200.225 255.255.255.0ip address 209.165.201.1 255.255.255.0 secondarycable helper-address 10.5.1.5! MAC level configurationcable bundle 1 masterint c4/0! No IP address! MAC layer configuration only



cable bundle 1

Subinterface Definition on Bundle Master Example

The following example shows how to define subinterfaces on a bundle master and define Layer 3 configurations for each subinterface:

interface c3/0 and interface c4/0 are bundled.

interface c3/0! No IP address! MAC level configuration onlycable bundle 1 master

interface c4/0! No IP address! MAC layer configurationcable bundle 1

! first subinterfaceinterface c3/0.1ip address 10.22.64.0 255.255.255.0cable helper-address 10.4.1.2

! second subinterfaceinterface c3/0.2ip address 10.12.39.0 255.255.255.0cable helper-address 10.4.1.2

! third subinterfaceinterface c3/0.3ip address 10.96.3.0 255.255.255.0cable helper-address 10.4.1.2

Cable Interface Bundle Master Configuration Example

The following examples show how to configure cable interface bundles:

Displaying the contents of the bundleRouter(config-if)# cable bundle ? <1-255> Bundle numberRouter(config-if)# cable bundle 25 ? master Bundle master <cr>Router(config-if)# cable bundle 25 master ? <cr>Router(config-if)# cable bundle 25 masterRouter(config-if)#07:28:17: %UBR7200-5-UPDOWN: Interface Cable3/0 Port U0, changed state to down07:28:18: %UBR7200-5-UPDOWN: Interface Cable3/0 Port U0, changed state to up

PE Router Configuration Example!! Identifies the version of Cisco IOS software installed.version 12.0

! Defines the hostname of the Cisco uBR7246hostname region-1-ubr!! Describes where the system is getting the software image it is running. In! this configuration example, the system is loading a Cisco uBR7246 image named



! AdamSpecial from slot 0.boot system flash slot0:ubr7200-p-mz.AdamSpecial!! Creates the enable secret password.enable secret xxxxenable password xxxx!! Sets QoS per modem for the cable plant.no cable qos permission createno cable qos permission updatecable qos permission modems!! Allows the system to use a full range of IP addresses, including subnet zero, for! interface addresses and routing updates.ip subnet-zero!! Enables Cisco Express Forwarding.ip cef!! Configures a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to insert the! DHCP relay agent information option in forwarded BOOTREQUEST messages.ip dhcp relay information option!! Enters the virtual routing forwarding (VRF) configuration mode and maps a VRF table to! the virtual private network (VPN) called MGMT-VPN. The VRF table contains the set of! routes that points to or gives routes to the CNR device, which provisions the cable! modem devices. Each VRF table defines a path through the MPLS cloud.ip vrf MGMT-VPN!! Creates the route distinguisher and creates the routing and forwarding table of the! router itself.rd 100:1

!! Creates a list of import and/or export route target communities for the VPN.route-target export 100:2route-target export 100:3

!! Maps a VRF table to the VPN called ISP1-VPN.ip vrf ISP1-VPN!! Creates the route distinguisher and creates the routing and forwarding table of the! router itself.rd 100:2

!! Creates a list of import and/or export route target communities for the VPN.route-target import 100:1

!! Maps a VRF table to the VPN called ISP2-VPN.ip vrf ISP2-VPN!! Creates the route distinguisher and creates the routing and forwarding table of the! router itself.rd 100:3

!! Creates a list of import and/or export route target communities for the VPN.route-target import 100:1

!! Maps a VRF table to the VPN called MSO-isp. Note: MSO-isp could be considered ISP-3; in! this case, the MSO is competing with other ISPs for other ISP services.ip vrf MSO-isp!! Creates the route distinguisher and creates the routing and forwarding table of the! router itself.rd 100:4



!! Creates a list of import and/or export route target communities for the VPN.

route-target import 100:1!! Builds a loopback interface to be used with MPLS and BGP; creating a loopback interface ! eliminates unnecessary updates (caused by physical interfaces going up and down) from! flooding the network.interface Loopback0ip address 10.0.0.0 255.255.255.0no ip directed-broadcast

!! Assigns an IP address to this Fast Ethernet interface. MPLS tag-switching must be! enabled on this interface.interface FastEthernet0/0description Connection to MSO core.ip address 10.0.0.0 255.255.255.0no ip directed-broadcastfull-duplextag-switching ip

!! Enters cable interface configuration mode and configures the physical aspects of the! 3/0 cable interface. Please note that no IP addresses are assigned to this interface;! they will be assigned instead to the logical subinterfaces. All other commands for! this cable interface should be configured to meet the specific needs of your cable RF! plant and cable network.interface Cable3/0no ip addressip directed-broadcastno ip mroute-cacheload-interval 30no keepalivecable downstream annex Bcable downstream modulation 64qamcable downstream interleave-depth 32cable downstream frequency 855000000cable upstream 0 frequency 30000000cable upstream 0 power-level 0no cable upstream 0 shutdowncable upstream 1 shutdowncable upstream 2 shutdowncable upstream 3 shutdowncable upstream 4 shutdowncable upstream 5 shutdown

!! Configures the physical aspects of the 3/0.1 cable subinterface. If cable modems have! not been assigned IP addresses, they will automatically come on-line using the settings! for subinterface X.1. interface Cable3/0.1description Cable Administration Network

!! Associates this interface with the VRF and MPLS VPNs that connect to the MSO cable! network registrar (CNR). The CNR provides cable modems with IP addresses and other! initialization parameters. ip vrf forwarding MSO

!! Defines a range of IP addresses and masks to be assigned to cable modems not yet associated with an ISP.ip address 10.0.0.0 255.255.255.0

!! Disables the translation of directed broadcasts to physical broadcasts.no ip directed-broadcast

!! Defines the DHCP server for cable modems whether they are associated with an ISP or! with the MSO acting as ISP.



cable helper-address 10.4.1.2 cable-modem!! Defines the DHCP server for PCs that are not yet associated with an ISP.cable helper-address 10.4.1.2 host

!! Disables cable proxy Address Resolution Protocol (ARP) and IP multicast echo on this! cable interface.no cable proxy-arpno cable ip-multicast-echo

!! Configures the physical aspects of the 3/0.2 cable subinterface.interface Cable3/0.2description MSO as ISP Network

!! Assigns this subinterface to the MPLS VPN used by the MSO to supply service to! customers—in this case, MSO-isp. ip vrf forwarding MSO-isp

!! Defines a range of IP addresses and masks to be assigned to cable modems associated! with the MSO as ISP network.ip address 10.1.0.0 255.255.255.0 secondary

! ! Defines a range of IP addresses and masks to be assigned to host devices associated! with the MSO as ISP network.ip address 10.1.0.0 255.255.255.0


!! Defines the DHCP server for cable modems whether they are associated with an ISP or! with the MSO acting as ISP.cable helper-address 10.4.1.2 cable-modem

!! Defines the DHCP server for PC host devices.cable helper-address 10.4.1.2 host


!! Configures the physical aspects of the 3/0.3 cable subinterfaceinterface Cable3/0.3 description ISP1's Network! ! Makes this subinterface a member of the MPLS VPN.ip vrf forwarding isp1


!! Defines a range of IP addresses and masks to be assigned to host devices associated! with the MSO as ISP network.ip address 10.0.1.1 255.255.255.0



!



! Defines the DHCP server for cable modems whether they are associated with an ISP or! with the MSO acting as ISP.cable helper-address 10.4.1.2 cable-modem


!! Configures the physical aspects of the 3/0.4 cable subinterfaceinterface Cable3/0.4description ISP2's Network

!! Makes this subinterface a member of the MPLS VPN.ip vrf forwarding isp2


!! Defines a range of IP addresses and masks to be assigned to host devices associated! with the MSO as ISP network.ip address 10.0.1.1 255.255.255.0



!!cable dhcp-giaddr policy

!!! Defines the DHCP server for cable modems whether they are associated with an ISP or! with the MSO acting as ISP.cable helper-address 10.4.1.2 cable-modem


!!end

P Router Configuration ExampleBuilding configuration...

Current configuration:!version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryption!hostname R7460-7206-02!enable password xxxx!ip subnet-zeroip cefip host brios 223.255.254.253!interface Loopback0 ip address 10.2.1.3 255.255.255.0



no ip directed-broadcast!interface Loopback1 no ip address no ip directed-broadcast no ip mroute-cache!interface FastEthernet0/0 ip address 1.7.108.2 255.255.255.0 no ip directed-broadcast no ip mroute-cache shutdown full-duplex no cdp enable!interface Ethernet1/0 ip address 10.0.1.2 255.255.255.0 no ip directed-broadcast no ip route-cache cef no ip mroute-cache tag-switching ip no cdp enable!interface Ethernet1/1 ip address 10.0.1.17 255.255.255.0 no ip directed-broadcast no ip route-cache cef no ip mroute-cache tag-switching ip no cdp enable!interface Ethernet1/2 ip address 10.0.2.2 255.255.255.0 no ip directed-broadcast no ip route-cache cef no ip mroute-cache tag-switching ip no cdp enable!interface Ethernet1/3 ip address 10.0.3.2 255.255.255.0 no ip directed-broadcast no ip route-cache cef no ip mroute-cache tag-switching ip no cdp enable!interface Ethernet1/4 ip address 10.0.4.2 255.255.255.0 no ip directed-broadcast no ip route-cache cef no ip mroute-cache tag-switching ip no cdp enable!interface Ethernet1/5 no ip address no ip directed-broadcast no ip route-cache cef shutdown no cdp enable!interface Ethernet1/6 no ip address



no ip directed-broadcast no ip route-cache cef shutdown no cdp enable!interface Ethernet1/7 no ip address no ip directed-broadcast no ip route-cache cef shutdown no cdp enable!router ospf 222 network 10.0.1.0 255.255.255.0 area 0 network 10.0.2.0 255.255.255.0 area 0 network 10.0.3.0 255.255.255.0 area 0 network 10.0.4.0 255.255.255.0 area 0 network 20.2.1.3 255.255.255.0 area 0!ip classlessno ip http server!!map-list test-bno cdp run!tftp-server slot0:master/120/c7200-p-mz.120-1.4!line con 0 exec-timeout 0 0 password xxxx login transport input noneline aux 0line vty 0 4 password xxxx login!no scheduler max-task-time



end

Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems

The network topology in Figure 54 shows two autonomous systems, which are configured as follows:

• Autonomous system 1 (AS1) includes PE1, P1, EBGP1. The IGP is OSPF.

• Autonomous system 2 (AS2) includes PE2, P2, EBGP2. The IGP is ISIS.

• CE1 and CE2 belongs to the same VPN, which is called VPN1.

• The P routers are route reflectors.

• EBGP1 is configured with the redistribute connected subnets router configuration command.

• EBGP2 is configured with the neighbor next-hop-self router configuration command.

Figure 54 Configuring Two Autonomous Systems

Autonomous System 1, CE1 ConfigurationCE1: Company ! interface Loopback1

ip address 1.0.0.6 255.255.255.255 ! interface Serial1/3

description Veritas no ip address encapsulation frame-relay frame-relay intf-type dce

! interface Serial1/3.1 point-to-point

description Veritas ip address 1.6.2.1 255.255.255.252 frame-relay interface-dlci 22

! router ospf 1

network 1.0.0.0 0.255.255.255 area 0

VPN1PE1

CE1

P1

EBGP1

AS1

VPN1P2

CE2

PE2

EBGP2

AS2

4786

6



Autonomous System 1, PE1 ConfigurationPE1: Company ! ip cef ! ip vrf V1

rd 1:105 route-target export 1:100 route-target import 1:100

! interface Serial0/0

description Burlington no ip address encapsulation frame-relay no fair-queue clockrate 2000000


description Burlington ip vrf forwarding V1 ip address 1.6.2.2 255.255.255.252 frame-relay interface-dlci 22

! interface Ethernet0/1

description Vermont ip address 100.2.2.5 255.255.255.0 tag-switching ip

! router ospf 1

log-adjacency-changes network 100.0.0.0 0.255.255.255 area 0

! router ospf 10 vrf V1

log-adjacency-changes redistribute bgp 1 metric 100 subnets network 1.0.0.0 0.255.255.255 area 0

! router bgp 1

no synchronization neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor 100.0.0.2 peer-group R no auto-summary

! address-family ipv4 vrf V1

redistribute ospf 10 no auto-summary no synchronization exit-address-family

! address-family vpnv4

neighbor R activate neighbor R send-community extended neighbor 100.0.0.2 peer-group R no auto-summary exit-address-family



Autonomous System 1, P1 ConfigurationP1: Company ! ip cef ! interface Loopback0

ip address 100.0.0.2 255.255.255.255 ! interface Ethernet0/1

description Ogunquit ip address 100.2.1.1 255.255.255.0 tag-switching ip

! interface FastEthernet2/0

description Veritas ip address 100.2.2.1 255.255.255.0 duplex auto speed auto tag-switching ip

! router ospf 1


! router bgp 1

no synchronization bgp log-neighbor-changes neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor R route-reflector-client neighbor 100.0.0.4 peer-group R neighbor 100.0.0.5 peer-group R


neighbor R activate neighbor R route-reflector-client neighbor R send-community extended neighbor 100.0.0.4 peer-group R neighbor 100.0.0.5 peer-group R exit-address-family

Autonomous System 1, EBGP1 ConfigurationEBGP1: Company ! ip cef ! interface Loopback0



! interface ATM1/0

description Lowell no ip address no atm scrambling cell-payload no atm ilmi-keepalive

! interface ATM1/0.1 point-to-point



description Lowell ip address 12.0.0.1 255.255.255.252 pvc 1/100

! router ospf 1

log-adjacency-changes redistribute connected subnets network 100.0.0.0 0.255.255.255 area 0

! router bgp 1

no synchronization no bgp default route-target filter bgp log-neighbor-changes neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor 12.0.0.2 remote-as 2 neighbor 100.0.0.2 peer-group R no auto-summary


neighbor R activate neighbor R send-community extended neighbor 12.0.0.2 activate neighbor 12.0.0.2 send-community extended neighbor 100.0.0.2 peer-group R no auto-summary exit-address-family

Autonomous System 2, EBGP2 ConfigurationEBGP2: Company ! ip cef ! ip vrf V1


! interface Loopback0

ip address 200.0.0.3 255.255.255.255 ip router isis


ip vrf forwarding V1 ip address 1.0.0.3 255.255.255.255


description Littleton no ip address encapsulation frame-relay load-interval 30 no fair-queue clockrate 2000000


description Littleton ip unnumbered Loopback0 ip router isis tag-switching ip frame-relay interface-dlci 23

! interface ATM1/0



description Ogunquit no ip address atm clock INTERNAL no atm scrambling cell-payload no atm ilmi-keepalive


description Ogunquit ip address 12.0.0.2 255.255.255.252 pvc 1/100

! router isis

net 49.0002.0000.0000.0003.00 ! router bgp 2

no synchronization no bgp default route-target filter bgp log-neighbor-changes neighbor 12.0.0.1 remote-as 1 neighbor 200.0.0.8 remote-as 2 neighbor 200.0.0.8 update-source Loopback0 neighbor 200.0.0.8 next-hop-self


redistribute connected no auto-summary no synchronization exit-address-family


neighbor 12.0.0.1 activate neighbor 12.0.0.1 send-community extended neighbor 200.0.0.8 activate neighbor 200.0.0.8 next-hop-self neighbor 200.0.0.8 send-community extended exit-address-family

Autonomous System 2, P2 ConfigurationP2: Company ! ip cef ! ip vrf V1







description Pax ip address 200.9.1.2 255.255.255.0 ip router isis tag-switching ip


description Lowell



no ip address encapsulation frame-relay frame-relay intf-type dce


description Lowell ip unnumbered Loopback0 ip router isis tag-switching ip frame-relay interface-dlci 23

! router isis

net 49.0002.0000.0000.0008.00 ! router bgp 2

no synchronization bgp log-neighbor-changes neighbor R peer-group neighbor R remote-as 2 neighbor R update-source Loopback0 neighbor R route-reflector-client neighbor 200.0.0.3 peer-group R neighbor 200.0.0.9 peer-group R












description Bethel no ip address encapsulation frame-relay frame-relay intf-type dce no fair-queue clockrate 2000000




description Bethel ip vrf forwarding V1 ip unnumbered Loopback1 frame-relay interface-dlci 24


description Littleton ip address 200.9.1.1 255.255.255.0 ip router isis tag-switching ip


log-adjacency-changes redistribute bgp 2 subnets network 1.0.0.0 0.255.255.255 area 0

! router isis

net 49.0002.0000.0000.0009.00 ! router bgp 2

no synchronization bgp log-neighbor-changes neighbor 200.0.0.8 remote-as 2 neighbor 200.0.0.8 update-source Loopback0


redistribute connected redistribute ospf 10 no auto-summary no synchronization exit-address-family address-family vpnv4 neighbor 200.0.0.8 activate neighbor 200.0.0.8 send-community extended exit-address-family


ip address 1.0.0.11 255.255.255.255 ! interface Serial0

description Pax no ip address encapsulation frame-relay no fair-queue clockrate 2000000

! interface Serial0.1 point-to-point

description Pax ip unnumbered Loopback0 frame-relay interface-dlci 24

! router ospf 1

network 1.0.0.0 0.255.255.255 area 0



Configuring EBGP Routing to Exchange VPN Routes Between Autonomous Systems in a Confederation

The network topology in Figure 55 shows a single ISP that is partitioning the backbone with confederations. The AS number of the provider is 100. The two autonomous systems run their own IGPs and are configured as follows:

• Autonomous system 1 (AS1) includes PE1, P1, EBGP1. The IGP is OSPF.

• Autonomous system 2 (AS2) includes PE2, P2, EBGP2. The IGP is ISIS.

• CE1 and CE2 belongs to the same VPN, which is called VPN1.

• The P routers are route reflectors.

• EBGP1 is configured with the redistribute connected subnets router configuration command.

• EBGP2 is configured with the neighbor next-hop-self router configuration command.

Figure 55 Configuring Two Autonomous Systems in a Confederation


ip address 1.0.0.6 255.255.255.255 ! interface Serial1/3

description Veritas no ip address encapsulation frame-relay frame-relay intf-type dce


description Veritas ip address 1.6.2.1 255.255.255.252 frame-relay interface-dlci 22

! router ospf 1

network 1.0.0.0 0.255.255.255 area 0

VPN1PE1

CE1

P1

ASBR1

AS1

VPN1P2

CE2

PE2

ASBR2

AS2

4786

7






description Burlington no ip address encapsulation frame-relay no fair-queue clockrate 2000000


description Burlington ip vrf forwarding V1 ip address 1.6.2.2 255.255.255.252 frame-relay interface-dlci 22

! interface Ethernet0/1


! router ospf 1



log-adjacency-changes redistribute bgp 1 metric 100 subnets network 1.0.0.0 0.255.255.255 area 0

! router bgp 1

no synchronization bgp confederation identifier 100 bgp confederation identifier 100 neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor 100.0.0.2 peer-group R no auto-summary


redistribute ospf 10 no auto-summary no synchronization exit-address-family


neighbor R activate neighbor R send-community extended neighbor 100.0.0.2 peer-group R no auto-summary exit-address-family



Autonomous System 1, P1 ConfigurationP1: Company ! ip cef ! interface Loopback0


description Ogunquit ip address 100.2.1.1 255.255.255.0 tag-switching ip


description Veritas ip address 100.2.2.1 255.255.255.0 duplex auto speed auto tag-switching ip

! router ospf 1


! router bgp 1

no synchronization bgp log-neighbor-changes bgp confederation identifier 100 neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor R route-reflector-client neighbor 100.0.0.4 peer-group R neighbor 100.0.0.5 peer-group R



Autonomous System 1, EBGP1 ConfigurationEBGP1: Company ! ip cef ! interface Loopback0



! interface ATM1/0

description Lowell no ip address no atm scrambling cell-payload no atm ilmi-keepalive

!



interface ATM1/0.1 point-to-point description Lowell ip address 12.0.0.1 255.255.255.252 pvc 1/100

! router ospf 1

log-adjacency-changes redistribute connected subnets network 100.0.0.0 0.255.255.255 area 0

! router bgp 1

no synchronization no bgp default route-target filter bgp log-neighbor-changes bgp confederation identifier 100 bgp confederation peers 1 neighbor R peer-group neighbor R remote-as 1 neighbor R update-source Loopback0 neighbor 12.0.0.2 remote-as 2 neighbor 12.0.0.2 next-hop-self neighbor 100.0.0.2 peer-group R no auto-summary


neighbor R activate neighbor R send-community extended neighbor 12.0.0.2 activate neighbor 12.0.0.2 next-hop-self neighbor 12.0.0.2 send-community extended neighbor 100.0.0.2 peer-group R no auto-summary exit-address-family

Autonomous System 2, EBGP2 ConfigurationEBGP2: Company ! ip cef ! ip vrf V1







description Littleton no ip address encapsulation frame-relay load-interval 30 no fair-queue clockrate 2000000


description Littleton ip unnumbered Loopback0



ip router isis tag-switching ip frame-relay interface-dlci 23

! interface ATM1/0

description Ogunquit no ip address atm clock INTERNAL no atm scrambling cell-payload no atm ilmi-keepalive


description Ogunquit ip address 12.0.0.2 255.255.255.252 pvc 1/100

! router isis

net 49.0002.0000.0000.0003.00 ! router bgp 2

no synchronization no bgp default route-target filter bgp log-neighbor-changes bgp confederation identifier 100 bgp confederation peers 1 neighbor 12.0.0.1 remote-as 1 neighbor 12.0.0.1 next-hop-self neighbor 200.0.0.8 remote-as 2 neighbor 200.0.0.8 update-source Loopback0 neighbor 200.0.0.8 next-hop-self




neighbor 12.0.0.1 activate neighbor 12.0.0.1 next-hop-self neighbor 12.0.0.1 send-community extended neighbor 200.0.0.8 activate neighbor 200.0.0.8 next-hop-self neighbor 200.0.0.8 send-community extended exit-address-family

Autonomous System 2, P2 ConfigurationP2: Company ! ip cef ! ip vrf V1









description Pax ip address 200.9.1.2 255.255.255.0 ip router isis tag-switching ip


description Lowell no ip address encapsulation frame-relay frame-relay intf-type dce


description Lowell ip unnumbered Loopback0 ip router isis tag-switching ip frame-relay interface-dlci 23

! router isis

net 49.0002.0000.0000.0008.00 ! router bgp 2

no synchronization bgp log-neighbor-changes bgp confederation identifier 100 neighbor R peer-group neighbor R remote-as 2 neighbor R update-source Loopback0 neighbor R route-reflector-client neighbor 200.0.0.3 peer-group R neighbor 200.0.0.9 peer-group R














description Bethel no ip address encapsulation frame-relay frame-relay intf-type dce no fair-queue clockrate 2000000


description Bethel ip vrf forwarding V1 ip unnumbered Loopback1 frame-relay interface-dlci 24


description Littleton ip address 200.9.1.1 255.255.255.0 ip router isis tag-switching ip


log-adjacency-changes redistribute bgp 2 subnets network 1.0.0.0 0.255.255.255 area 0

! router isis

net 49.0002.0000.0000.0009.00 ! router bgp 2

no synchronization bgp log-neighbor-changes bgp confederation identifier 100 neighbor 200.0.0.8 remote-as 2 neighbor 200.0.0.8 update-source Loopback0


redistribute connected redistribute ospf 10 no auto-summary no synchronization exit-address-family address-family vpnv4 neighbor 200.0.0.8 activate neighbor 200.0.0.8 send-community extended exit-address-family


ip address 1.0.0.11 255.255.255.255 ! interface Serial0

description Pax no ip address encapsulation frame-relay no fair-queue clockrate 2000000

! interface Serial0.1 point-to-point



description Pax ip unnumbered Loopback0 frame-relay interface-dlci 24

! router ospf 1

network 1.0.0.0 0.255.255.255 area 0

Implementing MPLS QoS ExampleFigure 56 illustrates a sample MPLS topology that implements the MPLS QoS feature. The following sections contain the configuration commands entered on Routers R1 to R6 and on Switches 1 and 2 included in this figure.

Figure 56 Sample MPLS Topology Implementing QoS

Configuring CEF Example

The following configuration commands enable CEF. CEF switching is a prerequisite for the MPLS feature and must be running on all routers in the network:

ip cef distributedtag-switching ip!

1897

0

Router 2

Router 4

lo0:10.10.10.10

lo0:11.11.11.11

Router 3

Router 5

lo0:13.13.13.13

lo0:16.16.16.16

Switch 1Switch 2

lo0:17.17.17.17

Router 6

e0/3e0/1

93.0.0.194.0.0.1

lo0:14.14.14.14

Router 1

p0/3

p0/3

p3/0/0

p3/0/0

e0/1

e0/1

a1/1/0

a0/0/3 a0/0/1

a2/0/0

a0/0/0

a0/1/1

a0/1/1h2/1/0

h3/1/0e0/2

e0/2

lo0:15.15.15.15

lo0:12.12.12.12

a1/1/0a0/0/0a1/1/0



Running IP on Router 2 Example

The following commands enable IP routing on Router 2. All routers must have IP enabled:

Note Router 2 is not part of the MPLS network.

!ip routing!hostname R2!interface Loopback0 ip address 10.10.10.10 255.255.255.255!interface POS0/3 ip unnumbered Loopback0crc 16 clock source internal!router ospf 100 network 10.0.0.0 0.255.255.255 area 100!

Running IP on Router 1 Example

The following commands enable IP routing on Router 1:

Note Router 1 is not part of the MPLS network.

ip routing !hostname R1!interface Loopback0 ip address 15.15.15.15 255.255.255.255!interface POS0/3 ip unnumbered Loopback0crc 16 clock source internal!router ospf 100 network 15.0.0.0 0.255.255.255 area 100

Running MPLS on Router 4 Example

Router 4 is a label edge router. CEF and the MPLS feature must be enabled on this router. CAR is also configured on Router 4 on interface POS3/0/0 (see the following section on configuring CAR).

!hostname R4!ip routingtag-switching iptag-switching advertise-tags!



ip cef distributed!interface Loopback0 ip address 11.11.11.11 255.255.255.255!interface Ethernet0/1 ip address 90.0.0.1 255.0.0.0tag-switching ip!

Configuring CAR Example

Lines 3 and 4 of the following sample configuration contain the CAR rate policies. Line 3 sets the committed information rate (CIR) at 155,000,000 bits and the normal burst/maximum burst size at 200,000/800,000 bytes. The conform action (action to take on packets) sets the IP precedence and sends the packets that conform to the rate limit. The exceed action sets the IP precedence and sends the packets when the packets exceed the rate limit.

!interface POS3/0/0 ip unnumbered Loopback0rate-limit input 155000000 2000000 8000000 conform-action set-prec-transmit 5exceed-action set-prec-transmit 1 ip route-cache distributed!router ospf 100 network 11.0.0.0 0.255.255.255 area 100 network 90.0.0.0 0.255.255.255 area 100


Router 3 is running MPLS. CEF and the MPLS feature must be enabled on this router. Router 3 contains interfaces that are configured for WRED, multi-VC, per-VC WRED, WFQ, and CAR. The following sections contain these sample configurations:

!hostname R3!ip cef distributed!interface Loopback0 ip address 12.12.12.12 255.255.255.255!interface Ethernet0/1 ip address 90.0.0.2 255.0.0.0tag-switching ip

Configuring Point-to-Point WRED Example

The following commands configure WRED on an ATM interface. In this example, the commands refer to a PA-A1 port adapter.

!interface ATM1/1/0ip route-cache distributed atm clock INTERNAL random-detect!



Configuring an Interface for Multi-VC Mode Example

The following commands configure interface ATM1/1/0 for multi-VC mode. In this example, the commands refer to a PA-A1 port adapter.

!interface ATM1/1/0.1 tag-switching ip unnumbered Loopback0tag-switching atm multi-vc tag-switching ip!

Configuring WRED and Multi-VC Mode on a PA-A3 Port-Adapter Interface Example

The commands to configure a PA-A3 port adapter differ slightly from the commands to configure a PA-A1 port adapter as shown previously.

On an PA-A3 port-adapter interface, distributed WRED (DWRED) is supported only per-VC, not per-interface.

To configure a PA-A3 port adapter, enter the following commands:

!interface ATM1/1/0ip route-cache distributedatm clock INTERNAL!interface ATM 1/1/0.1 tag-switchingip unnumbered Loopback0tag-switching multi-vc tag-switching random detect attach groupname!

Configuring Per-VC WRED Example

The following commands configure per-VC WRED on a PA-A3 port adapter only:

Note The PA-A1 port adapter does not support the per-VC WRED drop mechanism.

!interface ATM2/0/0 no ip addressip route-cache distributed

interface ATM2/0/0.1 point-to-point ip unnumbered Loopback0 no ip directed-broadcast pvc 10/100 random-detect encapsulation aal5snap exit ! tag-switching ip



Configuring WRED and WFQ Example

Lines 5 and 6 of the following sample configuration contain the commands for configuring WRED and WFQ on interface Hssi2/1/0:

!interface Hssi2/1/0 ip address 91.0.0.1 255.0.0.0ip route-cache distributedtag-switching ip random-detectfair queue toshssi internal-clock!

Configuring CAR Example

Lines 3 and 4 of the following sample configuration contain the CAR rate policies. Line 3 sets the CIR at 155,000,000 bits and the normal burst/maximum burst size at 200,000/800,000 bytes. The conform action (action to take on packets) sets the IP precedence and sends the packets that conform to the rate limit. The exceed action sets the IP precedence and sends the packets when the packets exceed the rate limit.

!interface POS3/0/0 ip unnumbered Loopback0rate-limit input 155000000 2000000 8000000 conform-action set-prec-transmit 2exceed-action set-prec-transmit 2 ip route-cache distributed!router ospf 100 network 12.0.0.0 0.255.255.255 area 100 network 90.0.0.0 0.255.255.255 area 100 network 91.0.0.0 0.255.255.255 area 100!ip route 93.0.0.0 255.0.0.0 Hssi2/1/0 91.0.0.2!


Router 5 is running the MPLS feature. CEF and MPLS must be enabled on this router. Router 5 has also been configured to create an ATM subinterface in multi-VC mode and to create a PVC on a point-to-point subinterface. The sections that follow contain these sample configurations.

!hostname R5!ip cef distributed!interface Loopback0 ip address 13.13.13.13 255.255.255.255!interface Ethernet0/2 ip address 92.0.0.1 255.0.0.0tag-switching ip



Configuring an ATM Interface Example

The following commands create an ATM interface:

!interface ATM1/0/0 no ip addressip route-cache distributed atm clock INTERNAL!

Configuring an ATM MPLS Subinterface in Multi-VC Mode Example

The following commands create an MPLS subinterface in multi-VC mode:

!interface ATM1/0/0.1 tag-switching ip unnumbered Loopback0tag-switching atm multi-vc tag-switching ip!

Configuring a PVC on Point-to-Point Subinterface Example

The following commands create a PVC on a point-to-point subinterface (interface ATM1/0/0.2).

!interface ATM1/0/0.2 point-to-point ip unnumbered Loopback0pvc 10/100 random-detect encapsulation aal5snap exit ! tag-switching ip!interface Hssi3/0 ip address 91.0.0.2 255.0.0.0tag-switching ip hssi internal-clock!router ospf 100 network 13.0.0.0 0.255.255.255 area 100 network 91.0.0.0 0.255.255.255 area 100 network 92.0.0.0 0.255.255.255 area 100!


Router 6 is running the MPLS feature. CEF and MPLS must be enabled on this router. The following commands configure MPLS on an ethernet interface:

!hostname R6!ip cef distributed!interface Loopback0 ip address 14.14.14.14 255.255.255.255!interface Ethernet0/1 ip address 93.0.0.1 255.0.0.0



tag-switching ip!interface Ethernet0/2 ip address 92.0.0.2 255.0.0.0 tag-switching ip!interface Ethernet0/3 ip address 94.0.0.1 255.0.0.0 tag-switching ip!router ospf 100 network 14.0.0.0 0.255.255.255 area 100 network 92.0.0.0 0.255.255.255 area 100 network 93.0.0.0 0.255.255.255 area 100 network 94.0.0.0 0.255.255.255 area 100!

Configuring ATM Switch 2 Example

Switch 2 is configured for MPLS and creates an ATM Forum PVC. The following commands configure MPLS on ATM switch2:

!hostname S2!interface Loopback0 ip address 16.16.16.16 255.255.255.255!interface ATM0/0/0 ip unnumbered Loopback0tag-switching ip!interface ATM0/0/1 ip unnumbered Loopback0 tag-switching ipatm pvc 10 100 interface ATM0/0/0 10 100

interface ATM0/0/2 no ip address no ip directed-broadcast!interface ATM0/0/3 ip unnumbered Loopback0tag-switching ip!interface ATM1/1/0ip unnumbered Loopback0tag-switching ip!router ospf 100 network 16.0.0.0 0.255.255.255 area 100!

Configuring ATM Switch 1 Example

Switch 1 is configured to create an ATM Forum PVC. The following commands configure MPLS on ATM switch1:

!hostname S1!



interface Loopback0 ip address 17.17.17.17 255.255.255.255!interface ATM0/0/0 ip unnumbered Loopback0tag-switching ip!

Configuring Label VCs and an ATM Forum PVC Example

Line 3 of the following sample configuration contains the configuration command for an ATM Forum PVC:

!interface ATM0/1/1 ip unnumbered Loopback0atm pvc 10 100 interface ATM0/0/0 10 100 tag-switching ip!interface ATM1/1/0 ip unnumbered Loopback0tag-switching ip!router ospf 100 network 17.0.0.0 0.255.255.255 area 100!

Configuring an MPLS LSC ExamplesThe following sections present the following MPLS LSC configuration examples:

• Configuring ATM-LSRs Example

• Configuring Multi-VCs Example

• Configuring ATM-LSRs with a Cisco 6400 NRP Operating as LSC Example

• Configuring ATM LSRs Through ATM Network Using Cisco 7200 LSCs Implementing Virtual Trunking Example

• Configuring ATM LSRs Through ATM Network Using Cisco 6400 NRP LSCs Implementing Virtual Trunking Example

• Configuring LSC Hot Redundancy Example

• Configuring LSC Warm Standby Redundancy Example

• Configuring an Interface Using Two VSI Partitions Example

• Using an Access List to Control the Creation of Headend VCs

Configuring ATM-LSRs Example

The network topology shown in Figure 57 incorporates two ATM-LSRs in an MPLS network. This topology includes two LSCs (Cisco 7200 routers), two BPX service nodes, and two edge LSRs (Cisco 7500 routers).

For the IGX, use the following commands:

extended-port atm1/0 descriptor 0.x.x.0 tag-control-protocol vsi slaves 32 id x



Figure 57 ATM-LSR Network Configuration Example

Based on Figure 57, the following configuration examples are provided:

• LSC1 Configuration

• BPX1 and BPX2 Configuration


• Edge LSR1 Configuration


LSC1 Configuration7200 LSC1:

ip cef !interface loopback0

ip address 192.103.210.5 255.255.255.255!interface ATM3/0

no ip addresstag-control-protocol vsi

!interface XTagATM13

extended-port ATM3/0 bpx 1.3ip unnumbered loopback0tag-switching atm vpi 2-15tag-switching ip



LSC1(Cisco 7200

series)

LSC2(Cisco 7200

series)

Cisco BPX1

ATM 3/0

ATM 2/0/0 ATM 2/0/0

ATM 3/0

1.11.1

Cisco BPX2

2.2 2.21.31.3Edge LSR1(Cisco 7500

series)

Edge LSR2(Cisco 7200

series)

ATM-LSR ATM-LSR

S69

08



BPX1 and BPX2 ConfigurationBPX1 and BPX2:

uptrk 1.1addshelf 1.1 v 1 1cnfrsrc 1.1 256 252207 y 1 e 512 6144 2 15 26000 100000uptrk 1.3cnfrsrc 1.3 256 252207 y 1 e 512 6144 2 15 26000 100000uptrk 2.2cnfrsrc 2.2 256 252207 y 1 e 512 4096 2 5 26000 100000

Note For the shelf controller, you must configure a VSI partition for the slave control port interface (addshelf 1.1, cnfrsrc 1.1...). However, do not configure an XTagATM port for the VSI partition (for example, XTagATM11).









!

Edge LSR1 Configuration7500 LSR1:

ip cef distributed !interface loopback 0

ip address 142.6.132.2 255.255.255.255!interface ATM2/0/0

no ip address!interface ATM2/0/0.5 tag-switching

ip unnumbered loopback 0tag-switching atm vpi 2-5tag-switching ip


ip cef interface loopback 0

ip address 142.6.142.2 255.255.255.255!



interface ATM2/0no ip address

!interface ATM2/0.9 tag-switching


Configuring Multi-VCs Example

When you configure multi-VC support, four label VCs for each destination are created by default, as follows:

• Standard (for class 0 and class 4 traffic)

• Available (for class 1 and class 5 traffic)

• Premium (for class 2 and class 6 traffic)

• Control (for class 3 and class 7 traffic)

This section provides examples for the following configurations, based on the sample network configuration shown earlier in Figure 57:






Note The IGX series ATM switches do not support QoS.


ip cef!interface loopback0




ip unnumbered loopback 0extended-port ATM3/0 bpx 1.3tag-switching atm vpi 2-15tag-switching atm cos available 25tag-switching atm cos standard 25tag-switching atm cos premium 25tag-switching atm cos control 25tag-switching ip


ip unnumbered loopback 0extended-port ATM3/0 bpx 2.2tag-switching atm vpi 2-5



tag-switching atm cos available 20tag-switching atm cos standard 30tag-switching atm cos premium 25tag-switching atm cos control 25tag-switching ip












ip cef distributedinterface loopback 0ip address 142.6.132.2 255.255.255.255 !interface ATM2/0/0


ip unnumbered loopback 0tag-switching atm vpi 2-5tag-switching atm multi-vctag-switching ip




ip cef interface loopback 0ip address 142.2.142.2 255.255.255.255 !interface ATM2/0

no ip address!interface ATM2/0.9 tag-switching

ip unnumbered loopback 0tag-switching atm vpi 2-5tag-switching atm multi-vctag-switching ip

QoS Support

If LSC1 supports QoS, but LSC2 does not, LSC1 makes VC requests for the following default classes:

• Control=QoS3

• Standard=QoS1

LSC2 ignores the call field in the request and allocates two UBR label VCs.

If LSR1 supports QoS, but LSR2 does not, LSR2 receives the request to create multiple label VCs, but by default, creates class 0 only (UBR).

Configuring ATM-LSRs with a Cisco 6400 NRP Operating as LSC Example

When you use the NRP as an MPLS LSC in the Cisco 6400 UAC, you must configure the NSP to provide connectivity between the NRP and the Cisco BPX switch. When configured in this way (as shown in Figure 58), the NRP is connected to the NSP by means of the internal interface ATM3/0/0, while external connectivity from the Cisco 6400 UAC to the Cisco BPX switch is provided by means of the external interface ATM1/0/0 from the NSP.



Figure 58 Cisco 6400 UAC NRP Operating As an LSC


• 6400 UAC NSP Configuration

• 6400 UAC NRP LSC1 Configuration


• 6400 UAC NRP LSC2 Configuration



6400 UAC NSP Configuration6400 NSP:

!interface ATM3/0/0

atm pvp 0 interface ATM1/0/0 0atm pvp 2 interface ATM1/0/0 2 atm pvp 3 interface ATM1/0/0 3 atm pvp 4 interface ATM1/0/0 4 atm pvp 5 interface ATM1/0/0 5atm pvp 6 interface ATM1/0/0 6 atm pvp 7 interface ATM1/0/0 7 atm pvp 8 interface ATM1/0/0 8 atm pvp 9 interface ATM1/0/0 9atm pvp 10 interface ATM1/0/0 10 atm pvp 11 interface ATM1/0/0 11atm pvp 12 interface ATM1/0/0 12atm pvp 13 interface ATM1/0/0 13atm pvp 14 interface ATM1/0/0 14 atm pvp 15 interface ATM1/0/0 15

3078

8

LSC1(7200)

LSC2(7200)

BPX1

1.1

BPX2Cisco BPX1 Cisco BPX2Edge LSR1(Cisco 7500)

Edge LSR2(Cisco 7500)

ATM-LSR ATM-LSR

LSC(NRP)

LSC(NRP)

NSP NSP

ATM 1/0/0 ATM 1/0/0

ATM 3/0/0 ATM 3/0/0

Cisco 6400Cisco 6400

atm2/0/02.2

1.1

1.3 1.3atm2/0/0 2.2



Note Instead of configuring multiple PVCs, you can also configure PVP 0 by deleting all well-known VCs. For example, you can use the atm manual-well-known-vc delete interface command on both interfaces and then configure PVP 0, as follows: atm pvp 0 interface ATM1/0/0 0

6400 UAC NRP LSC1 Configurationip cef!interface Loopback0 ip address 142.2.143.22 255.255.255.255!interface ATM0/0/0no ip addresstag-control-protocol vsi!interface XTagATM13 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 1.3 tag-switching atm vpi 2-15 tag-switching ip!interface XTagATM22 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 2.2 tag-switching atm vpi 2-5 tag-switching ip!tag-switching atm disable-headend-vc



Note For the shelf controller, you must configure a VSI partition for the slave control port interface (addshelf 1.1, cnfrsrc 1.1...). However, do not configure an XTagATM port for the VSI partition (for example, XTagATM11).

6400 UAC NRP LSC2 Configurationip cef!interface Loopback0 ip address 192.103.210.5 255.255.255.255!interface ATM0/0/0no ip addresstag-control-protocol vsi!interface XTagATM13 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 1.3 tag-switching atm vpi 2-15



tag-switching ip!interface XTagATM22 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 2.2 tag-switching atm vpi 2-5 tag-switching ip!tag-switching atm disable-headend-vc










unnumbered loopback 0tag-switching atm vpi 2-5tag-switching ip

Configuring ATM LSRs Through ATM Network Using Cisco 7200 LSCs Implementing Virtual Trunking Example

The network topology shown in Figure 59 incorporates two ATM-LSRs using virtual trunking to create an MPLS network through a private ATM Network. This topology includes the following:

• Two LSCs (Cisco 7200 routers)

• Two BPX service nodes

• Two edge LSRs (Cisco 7500 and 7200 routers)





Figure 59 ATM-LSR Virtual Trunking Through an ATM Network


• LSC1 Implementing Virtual Trunking Configuration


• LSC2 Implementing Virtual Trunking Configuration



LSC1 Implementing Virtual Trunking Configuration7200 LSC1:





extended-port ATM3/0 bpx 1.3.2ip unnumbered loopback0tag-switching atm vp-tunnel 2tag-switching ip



LSC1(Cisco 7200)

LS(Cisco

Cisco BPX1

ATM 3/0

ATM 2/0/0

A

1.11.1

Cisco

2.2 1.3.21.3.2


ATM-LSR ATM

ATMnetwork




uptrk 1.1addshelf 1.1 v 1 1cnfrsrc 1.1 256 252207 y 1 e 512 6144 2 15 26000 100000uptrk 1.3.2cnftrk 1.3.2 100000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR,RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 2

cnfrsrc 1.3.2 256 252207 y 1 e 512 6144 2 2 26000 100000uptrk 2.2cnfrsrc 2.2 256 252207 y 1 e 512 4096 2 5 26000 100000

Note For the shelf controller, you must configure a VSI partition for the slave control port interface (addshelf 1.1, cnfrsrc 1.1...). However, do not configure an XtagATM port for the VSI partition (for example, XtagATM11).

LSC2 Implementing Virtual Trunking Configuration7200 LSC2:





extended-port ATM3/0 bpx 1.3.2ip unnumbered loopback0tag-switching atm vp-tunnel 2tag-switching ip




ip cef distributed interface loopback 0





ip cef interface loopback 0

ip address 142.6.142.2 255.255.255.255!



interface ATM2/0no ip address



Configuring ATM LSRs Through ATM Network Using Cisco 6400 NRP LSCs Implementing Virtual Trunking Example

The network topology shown in Figure 60 incorporates two ATM-LSRs using virtual trunking to create an MPLS network through a private ATM network. This topology includes two LSCs (Cisco 6400 UAC NRP routers), two BPX service nodes, and two edge LSRs (Cisco 7500 and 7200 routers).

Figure 60 Cisco 6400 NRP Operating as LSC Implementing Virtual Trunking


• 6400 UAC NSP Configuration

• 6400 UAC NRP LSC1 Implementing Virtual Trunking Configuration


• 6400 UAC NRP LSC2 Implementing Virtual Trunking Configuration



LSC1(7200)

LSC2(7200)

BPX1

1.1

BPX2Cisco BPX1 Cisco BPX2



ATM-LSR ATM-LSR

LSC(NRP)

LSC(NRP)

NSP NSP

ATM 1/0/0 ATM 1/0/0

ATM 3/0/0 ATM 3/0/0

Cisco 6400Cisco 6400

ATM 2/0/02.2

1.1

1.3.2 1.3.2ATM 2/0/0 2.2ATMnetwork

3408

5



6400 UAC NSP Configuration6400 NSP:

!interface ATM3/0/0

atm pvp 0 interface ATM1/0/0 0atm pvp 2 interface ATM1/0/0 2 atm pvp 3 interface ATM1/0/0 3 atm pvp 4 interface ATM1/0/0 4 atm pvp 5 interface ATM1/0/0 5atm pvp 6 interface ATM1/0/0 6 atm pvp 7 interface ATM1/0/0 7 atm pvp 8 interface ATM1/0/0 8 atm pvp 9 interface ATM1/0/0 9atm pvp 10 interface ATM1/0/0 10 atm pvp 11 interface ATM1/0/0 11atm pvp 12 interface ATM1/0/0 12atm pvp 13 interface ATM1/0/0 13atm pvp 14 interface ATM1/0/0 14 atm pvp 15 interface ATM1/0/0 15

Note Instead of configuring multiple PVCs, you can also configure PVP 0 by deleting all well-known VCs. For example, you can use the atm manual-well-known-vc delete interface command on both interfaces and then configure PVP 0, as follows: atm pvp 0 interface ATM1/0/0 0

6400 UAC NRP LSC1 Implementing Virtual Trunking Configurationip cef!interface Loopback0 ip address 142.2.143.22 255.255.255.255!interface ATM0/0/0no ip addresstag-control-protocol vsi!interface XTagATM132 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 1.3.2 tag-switching atm vp-tunnel 2 tag-switching ip!interface XTagATM22 ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 2.2 tag-switching atm vpi 2-5 tag-switching ip!tag-switching atm disable-headend-vcBPX1 and BPX2 ConfigurationBPX1 and BPX2:uptrk 1.1addshelf 1.1 v 1 1cnfrsrc 1.1 256 252207 y 1 e 512 6144 2 15 26000 100000uptrk 1.3.2cnftrk 1.3.2 100000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR,RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 2cnfrsrc 1.3.2 256 252207 y 1 e 512 6144 2 2 26000 100000uptrk 2.2cnfrsrc 2.2 256 252207 y 1 e 512 4096 2 5 26000 100000




6400 UAC NRP LSC2 Implementing Virtual Trunking Configurationip cef!interface Loopback0




ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 1.3.2 tag-switching atm vp-tunnel 2 tag-switching ip


ip unnumbered Loopback0 extended-port ATM0/0/0 bpx 2.2 tag-switching atm vpi 2-5 tag-switching ip

!tag-switching atm disable-headend-vc










unnumbered loopback 0tag-switching atm vpi 2-5tag-switching ip



Configuring LSC Hot Redundancy Example

The network topology shown in Figure 61 incorporates two ATM-LSRs in an MPLS network. This topology includes two LSCs on each BPX node and four edge LSRs.

The following configuration examples show the label-switching configuration for both standard downstream-on-demand interfaces and downstream on demand over a VP-tunnel. The difference between these two types of configurations is as follows:

• Standard interface configuration configures a VPI range of one or more VPIs while LDP control information flows in PVC 0,32.

• VP-tunnel configures a single VPI (such as vpi 12) and uses a tag-switching atm control-vc of vpi,32 global configuration command (for example, 12,32). You can use a VP-tunnel to establish label-switching neighbor relationships through a private ATM cloud.

The following configuration examples are provided in this section:

• LSC 1A Configuration

• LSC 1B Configuration

• LSC 2A Configuration

• LSC 2B Configuration


• Edge LSR 7200-1 Configuration






Figure 61 ATM-LSR Network Configuration Example

7200-1LER

LSC 1A7200

LSC 1B7200

7500-1LER

ATM cloud

BPX-1

1.2

1.1

a3/0

a2/0

a3/0

a2/0/0

a2/0/0

a3/0/0

a2/0

a3/0a3/0

3563

7

a3/0

2.1 1.1 2.1

2.21.52.5

1.6.121.6.22

2.6.122.6.22

7500-2LER

7200-2LER

LSC 2A7200

LSC 2B7200

BPX-2

1.52.5

1.22.2

2.6.122.6.22

1.6.121.6.22



Note In the following configuration examples for the LSCs, you can use the tag-switching request-tags for global configuration command instead of the tag-switching atm disable headend-vc global configuration command.

LSC 1A Configuration7200 LSC 1A:

ip cef !tag-switching atm disable-headend vc!interface loopback0


no ip addresstag-control-protocol vsi id 1


ip unnumbered loopback0extended-port ATM3/0 bpx 1.2tag-switching atm vpi 2-5tag-switching ip




ip unnumbered loopback0extended-port ATM3/0 bpx 1.6.12tag-switching atm vp-tunnel 12tag-switching ip



LSC 1B Configuration7200 LSC 1B:

ip cef !tag-switching atm disable-headend vc!!interface loopback0




ip unnumbered loopback0extended-port ATM3/0 bpx 2.2tag-switching atm vpi 2-5



tag-switching ip!interface XTagATM25






LSC 2A Configuration7200 LSC 2A:














LSC 2B Configuration7200 LSC 2B:













uptrk 1.1addshelf 1.1 vsi 1 1cnfrsrc 1.1 256 252207 y 1 e 512 6144 2 15 26000 100000upln 1.2upport 1.2cnfrsrc 1.2 256 252207 y 1 e 512 6144 2 5 26000 100000uptrk 1.5cnfrsrc 1.5 256 252207 y 1 e 512 6144 2 15 26000 100000uptrk 1.6.12cnftrk 1.6.12 110000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR, RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 12cnfrsrc 1.6.12 256 252207 y 1 e 512 6144 12 12 26000 100000uptrk 1.6.22cnftrk 1.6.22 110000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR, RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 22cnfrsrc 1.6.22 256 252207 y 2 e 512 6144 22 22 26000 100000uptrk 2.1addshelf 2.1 vsi 2 2cnfrsrc 2.1 256 252207 y 2 e 512 6144 2 15 26000 100000upln 2.2upport 2.2cnfrsrc 2.2 256 252207 y 2 e 512 4096 2 5 26000 100000



uptrk 2.5cnfrsrc 2.5 256 252207 y 2 e 512 6144 2 15 26000 100000uptrk 2.6.12cnftrk 2.6.12 110000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR, RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 12cnfrsrc 2.6.12 256 252207 y 1 e 512 6144 12 12 26000 100000uptrk 2.6.22cnftrk 2.6.22 110000 N 1000 7F V,TS,NTS,FR,FST,CBR,NRT-VBR,ABR, RT-VBR N TERRESTRIAL 10 0 N N Y Y Y CBR 22cnfrsrc 2.6.22 256 252207 y 2 e 512 6144 22 22 26000 100000


Edge LSR 7200-1 Configuration7200-1 edge LSR:





!interface ATM3/0

no ip address

interface ATM3/0.22 tag-switchingip unnumbered loopback 0tag-switching atm vpi 2-5tag-switching ip


ip cef distributed !interface loopback0



ip unnumbered loopback0tag-switching atm vp-tunnel 12tag-switching ip

!interface ATM2/0/0.1622 tag-switching





ip cef distributed !interface loopback0



ip unnumbered loopback0tag-switching atm vpi 2-5tag-switching ip

!!interface ATM3/0/0


ip unnumbered loopback0tag-switching atm vpi 2-5tag-switching ip








Configuring LSC Warm Standby Redundancy Example

The configuration of LSC Warm Standby redundancy can be implemented by configuring the redundant link for either a higher routing cost than the primary link or configuring a bandwidth allocation that is less desirable. This needs to be performed only at the edge LSR nodes, because the LSCs have been configured to disable the creation of headend VCs, which reduces the LVC overhead.



Configuring an Interface Using Two VSI Partitions Example

A special case may arise where a network topology can only support a neighbor relationship between peers using a single trunk or line interface. To configure the network, perform the following steps:

Step 1 Configure the interface to use both VSI partitions. The VSI partition configuration for the interface must be made with no overlapping VP space. For example, for interface 2.8 on the ATM-LSR, the following configuration is required:

uptrk 2.8cnfrsrc 2.8 256 252207 y 1 e 512 6144 2 15 26000 100000cnfrsrc 2.8 256 252207 y 2 e 512 6144 16 29 26000 100000

Thus partition 1 will create LVCs using VPIs 2-15 and partition 2 will create LVCs using VPIs 16-29.

Step 2 Configure the control-vc. Each LSC requires a control VC (default 0,32); however, only one LSC can use this defeat control-vc for any one trunk interface. The following command forces the control VC assignment.

tag-switching atm control-vc <vpi>,<vci>

Therefore, LSC 1 XTagATM28 can use the default control-vc 0,32 (but it is suggested that you use 2,32 to reduce configuration confusion) and the LSC 2 XTagATM28 should use control-vc 16,32.



The following example shows the configuration steps:

LSC1 Configurationinterface XTagATM2801ip unnumbered loopback0extended-port ATM3/0 bpx 2.8tag-switching atm vpi 2-15tag-switching atm control-vc 2 32tag-switching ip

LSC2 Configurationinterface XTagATM2802ip unnumbered loopback0extended-port ATM3/0 bpx 2.8tag-switching atm vpi 16-29tag-switching atm control-vc 16 32tag-switching ip



Using an Access List to Control the Creation of Headend VCs

The following example shows how to use an access list to control the creation of headend VCs in an MPLS network, which allows the network to support more destinations.

Figure 62 shows two edge LSRs and two ATM-LSRs. In the configuration, only LSPs between edge LSRs are required to provide label switched paths. Other LSPs are not essential. The LSPs between LSCs and between the LSCs and the edge LSRs are often unused and required only for monitoring and maintaining the network. In such cases the IP forwarding path is sufficient.

Figure 62 Sample MPLS Network

In networks that require connections only between edge LSRs, you can use the access list to eliminate the creation of unnecessary LSPs. This allows LVC resources to be conserved so that more edge LSR connections can be supported.

To prevent creation of LSPs between LSCs, create an access list that denies all 192.0.0.0/24 addresses. Then, to prevent creation of LVCs from the LSCs to the edge LSRs, create an access list that denies all 198.0.0.0/24 addresses. The configuration examples for LSC 1 and 2 show the commands for performing these tasks.

To prevent creation of LVCs from the edge LSRs to LSCs, create an access list at the edge LSRs that denies all 192.0.0.0/24 addresses. The configuration examples for edge LSR 1 and 2 show the commands for performing this task.

LSC 1 Configuration7200 LSC1:

ip cef !tag-switching request-tags for acl_lscip access-list standard acl_lscdeny 192.0.0.0 0.255.255.255deny 198.0.0.0 0.255.255.255permit any!interface loopback0



!

LSC 1192.0.0.1

LSC 1192.0.0.1

Edge LSR 1198.0.0.1

Edge LSR 2198.0.0.2

BPX 2BPX 1

ATM-LSRATM-LSR 4692

9

2.2 1.3 1.3

a2/0/0

2.2

a2/0



interface XTagATM13extended-port ATM3/0 bpx 1.3ip unnumbered loopback0tag-switching atm vpi 2-15tag-switching ip






LSC 2 Configuration7200 LSC2:

ip cef !tag-switching request-tags for acl_lscip access-list standard acl_lscdeny 192.0.0.0 0.255.255.255deny 198.0.0.0 0.255.255.255permit any!interface loopback0







!



Edge LSR 1 Configuration7500 LSR1:

ip cef distributed !tag-switching request-tags for acl_lerip access-list standard acl_lerdeny 192.0.0.0 0.255.255.255permit any!interface loopback 0




Edge LSR 2 Configuration7200 LSR2:

ip cef !tag-switching request-tags for acl_lerip access-list standard acl_lerdeny 192.0.0.0 0.255.255.255permit any!interface loopback 0




MPLS Egress NetFlow Accounting ExampleIn the following example, the VPN routing and forwarding (VRF) instances currently configured in the router is displayed:

Router# show ip vrf

Name Default RD Interfaces vpn1 100:1 Ethernet1/4 Loopback1 vpn3 300:1 Ethernet1/2 Loopback2Router# configure terminal

Enter configuration commands, one per line. End with CNTL/Z.Router(config)# interface eth1/4Router(config-if)# mpls ? ip Configure dynamic MPLS forwarding for IP label-protocol Configure label/tag distribution protocol (LDP/TDP) mtu Set tag switching Maximum Transmission Unit



netflow Configure Egress Netflow Accounting traffic-eng Configure Traffic Engineering parameters

Router(config-if)# mpls netRouter(config-if)# mpls netflow ? egress Enable Egress Netflow Accounting

MPLS egress NetFlow accounting is enabled on interface eth1/4 and debugging is turned on, as follows:

Router(config-if)# mpls netflow egressRouter(config-if)# Router(config-if)# Router# debug mpls netflowMPLS Egress NetFlow debugging is onRouter#

The following example shows the current configuration in the router:

Router# show runBuilding configuration...

Current configuration:!version 12.0service timestamps debug uptimeservice timestamps log uptimeno service password-encryption

ip cefno ip domain-lookup!

The VRF is defined, as follows:

ip vrf vpn1 rd 100:1 route-target export 100:1 route-target import 100:1!interface Loopback0 ip address 41.41.41.41 255.255.255.255 no ip directed-broadcast no ip mroute-cache!interface Ethernet1/4 ip vrf forwarding vpn1 ip address 180.1.1.1 255.255.255.0 no ip directed-broadcastmpls netflow egress!

Multilayer Switching


Multilayer Switching Overview

This chapter provides an overview of Multilayer Switching (MLS).

Note The information in this chapter is a brief summary of the information contained in the Catalyst 5000 Series Multilayer Switching User Guide. The commands and configurations described in this guide apply only to the devices that provide routing services. Commands and configurations for Catalyst 5000 series switches are documented in the Catalyst 5000 Series Multilayer Switching User Guide.

MLS provides high-performance Layer 3 switching for Cisco routers and switches. MLS switches IP data packets between subnets using advanced application-specific integrated circuit (ASIC) switching hardware. Standard routing protocols, such as Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (Enhanced IGRP), Routing Information Protocol (RIP), and Intermediate System-to-Intermediate System (IS-IS), are used for route determination.

MLS enables hardware-based Layer 3 switching to offload routers from forwarding unicast IP data packets over shared media networking technologies such as Ethernet. The packet forwarding function is moved onto Layer 3 Cisco series switches whenever a partial or complete switched path exists between two hosts. Packets that do not have a partial or complete switched path to reach their destinations still use routers for forwarding packets.

MLS also provides traffic statistics as part of its switching function. These statistics are used for identifying traffic characteristics for administration, planning, and troubleshooting. MLS uses NetFlow Data Export (NDE) to export the flow statistics.

Procedures for configuring MLS and NDE on routers are provided in the “Configuring IP Multilayer Switching” chapter.

Procedures for configuring MLS and NDE on routers are provided in the following chapters in this publication:

• “Configuring IP Multilayer Switching” chapter

• “Configuring IP Multicast Multilayer Switching” chapter

• “Configuring IPX Multilayer Switching” chapter

This chapter describes MLS. It contains the following sections:

• Terminology

• Introduction to MLS

• Key MLS Features

• MLS Implementation

• Standard and Extended Access Lists

Multilayer Switching OverviewTerminology


• Introduction to IP Multicast MLS

• Introduction to IPX MLS

• Guidelines for External Routers

• Features That Affect MLS

TerminologyThe following terminology is used in the MLS chapters:

• Multilayer Switching-Switching Engine (MLS-SE)—A NetFlow Feature Card (NFFC)-equipped Catalyst 5000 series switch.

• Multilayer Switching-Route Processor (MLS-RP)—A Cisco router with MLS enabled.

• Multilayer Switching Protocol (MLSP)—The protocol running between the MLS-SE and MLS-RP to enable MLS.

Introduction to MLSLayer 3 protocols, such as IP and Internetwork Packet Exchange (IPX), are connectionless—they deliver each packet independently of each other. However, actual network traffic consists of many end-to-end conversations, or flows, between users or applications.

A flow is a unidirectional sequence of packets between a particular source and destination that share the same protocol and transport-layer information. Communication from a client to a server and from the server to the client is in separate flows. For example, HTTP Web packets from a particular source to a particular destination are in a separate flow from File Transfer Protocol (FTP) file transfer packets between the same pair of hosts.

Flows can be based on only Layer 3 addresses. This feature allows IP traffic from multiple users or applications to a particular destination to be carried on a single flow if only the destination IP address is used to identify a flow.

The NFFC maintains a Layer 3 switching table (MLS cache) for the Layer 3-switched flows. The cache also includes entries for traffic statistics that are updated in tandem with the switching of packets. After the MLS cache is created, packets identified as belonging to an existing flow can be Layer 3-switched based on the cached information. The MLS cache maintains flow information for all active flows. When the Layer 3-switching entry for a flow ages out, the flow statistics can be exported to a flow collector application.

For information on multicast MLS, see the “Introduction to IP Multicast MLS” section in this chapter.

Multilayer Switching OverviewKey MLS Features


Key MLS FeaturesTable 37 lists the key MLS features.

Table 37 Summary of Key Features

Feature Description

Ease of Use Is autoconfigurable and autonomously sets up its Layer 3 flow cache. Its “plug-and-play” design eliminates the need for you to learn new IP switching technologies.

Transparency Requires no end-system changes and no renumbering of subnets. It works with DHCP1 and requires no new routing protocols.

1. DHCP = Dynamic Host Configuration Protocol

Standards Based Uses IETF2 standard routing protocols such as OSPF and RIP for route determination. You can deploy MLS in a multivendor network.

2. IETF = Internet Engineering Task Force

Investment Protection Provides a simple feature-card upgrade on the Catalyst 5000 series switches. You can use MLS with your existing chassis and modules. MLS also allows you to use either an integrated RSM or an external router for route processing and Cisco IOS services.

Fast Convergence Allows you to respond to route failures and routing topology changes by performing hardware-assisted invalidation of flow entries.

Resilience Provides the benefits of HSRP3 without additional configuration. This feature enables the switches to transparently switch over to the Hot Standby backup router when the primary router goes offline, eliminating a single point of failure in the network.

3. HSRP = Hot Standby Router Protocol

Access Lists Allows you to set up access lists to filter, or to prevent traffic between members of different subnets. MLS enforces multiple security levels on every packet of the flow at wire speed. It allows you to configure and enforce access control rules on the RSM. Because MLS parses the packet up to the transport layer, it enables access lists to be validated. By providing multiple security levels, MLS enables you to set up rules and control traffic based on IP addresses and transport-layer application port numbers.

Accounting and Traffic Management

Allows you to see data flows as they are switched for troubleshooting, traffic management, and accounting purposes. MLS uses NDE to export the flow statistics. Data collection of flow statistics is maintained in hardware with no impact on switching performance. The records for expired and purged flows are grouped and exported to applications such as NetSys for network planning, RMON24 traffic management and monitoring, and accounting applications.

4. RMON2 = Remote Monitoring 2

Network Design Simplification

Enables you to speed up your network while retaining the existing subnet structure. It makes the number of Layer 3 hops irrelevant in campus design, enabling you to cope with increases in any-to-any traffic.

Media Speed Access to Server Farms

You do not need to centralize servers in multiple VLANs to get direct connections. By providing security on a per-flow basis, you can control access to the servers and filter traffic based on subnet numbers and transport-layer application ports without compromising Layer 3 switching performance.

Faster Interworkgroup Connectivity

Addresses the need for higher-performance interworkgroup connectivity by intranet and multimedia applications. By deploying MLS, you gain the benefits of both switching and routing on the same platform.

Multilayer Switching OverviewMLS Implementation


MLS ImplementationThis section provides a step-by-step description of MLS implementation.

Note The MLS-RPs shown in the figures represent either a RSM or an externally attached Cisco router.

The MLSP informs the Catalyst 5000 series switch of the MLS-RP MAC addresses used on different VLANs and the MLS-RP’s routing and access list changes. Through this protocol, the MLS-RP multicasts its MAC and VLAN information to all MLS-SEs. When the MLS-SE hears the MLSP hello message indicating an MLS initialization, the MLS-SE is programmed with the MLS-RP MAC address and its associated VLAN number (see Figure 63).

Figure 63 MLS Implementation

In Figure 64, Host A and Host B are located on different VLANs. Host A initiates a data transfer to Host B. When Host A sends the first packet to the MLS-RP, the MLS-SE recognizes this packet as a candidate packet for Layer 3 switching because the MLS-SE has learned the MLS-RP’s destination MAC address and VLAN through MLSP. The MLS-SE learns the Layer 3 flow information (such as the destination address, source address, and protocol port numbers), and forwards the first packet to the MLS-RP. A partial MLS entry for this Layer 3 flow is created in the MLS cache.

The MLS-RP receives the packet, looks at its route table to determine how to forward the packet, and applies services such as Access Control Lists (ACLs) and class of service (COS) policy.

The MLS-RP rewrites the MAC header adding a new destination MAC address (Host B’s) and its own MAC address as the source.

MLS-RP multicasts itsMAC addresses andVLAN number to allMLS-SEs…

… all MLS-SEsprogram the NFFCwith the MSLP hellomessage information

MLS-RP

(MLS-SE) 1200

0

Multilayer Switching OverviewMLS Implementation



The MLS-RP routes the packet to Host B. When the packet appears back on the Catalyst 5000 series switch backplane, the MLS-SE recognizes the source MAC address as that of the MLS-RP, and that the packet’s flow information matches the flow for which it set up a candidate entry. The MLS-SE considers this packet an enabler packet and completes the MLS entry (established by the candidate packet) in the MLS cache (see Figure 65).


After the MLS entry has been completed, all Layer 3 packets with the same flow from Host A to Host B are Layer 3 switched directly inside the switch from Host A to Host B, bypassing the router (see Figure 66). After the Layer 3-switched path is established, the packet from Host A is rewritten by the MLS-SE before it is forwarded to Host B. The rewritten information includes the MAC addresses, encapsulations (when applicable), and some Layer 3 information.

The resultant packet format and protocol behavior is identical to that of a packet that is routed by the RSM or external Cisco router.

Note MLS is unidirectional. For Host B to communicate with Host A, another Layer 3-switched path needs to be created from Host B to Host A.

MLS-RP

(MLS-SE)

1200

1

Host A Host B

Because the Catalyst switch has learnedthe MAC and VLAN information of the MLS-RP,the switch starts the MLS process for the Layer 3flow contained in this packet, the candidate packet

Candidate packet

MLS-RP

(MLS-SE)

1200

2

Host A Host B

The MLS-RP routes this packet to Host B. Because the MLS-SE has learned both this MLS-RP and the Layer 3 flow in this packet, it completes the MLS entry in the MLS cache. The first routed packet is called the enabler packet

Enabler packet

Multilayer Switching OverviewStandard and Extended Access Lists



See the Catalyst 5000 Series Multilayer Switching User Guide for additional network implementation examples that include network topologies that do not support MLS.

Standard and Extended Access Lists

Note Router interfaces with input access lists cannot participate in MLS. However, any input access list can be translated to an output access list to provide the same effect on the interface. For complete details on how input and output access lists affect MLS, see the chapter “Configuring Multilayer Switching.”

MLS allows you to enforce access lists on every packet of the flow without compromising MLS performance. When you enable MLS, standard and extended access lists are handled at wire speed by the MLS-SE. Access lists configured on the MLS-RP take effect automatically on the MLS-SE.

Additionally, route topology changes and the addition of access lists are reflected in the switching path of MLS.

Consider the case where an access list is configured on the MLS-RP to deny access from Station A to Station B. When Station A wants to communicate with Station B, it sends the first packet to the MLS-RP. The MLS-RP receives this packet and checks to learn if this packet flow is permitted. If an ACL is configured for this flow, the packet is discarded. Because the first packet for this flow does not return from the MLS-RP, an MLS cache entry is not established by the MLS-SE.

In another case, access lists are introduced on the MLS-RP while the flow is already being Layer 3 switched within the MLS-SE. The MLS-SE immediately enforces security for the affected flow by purging it.

Similarly, when the MLS-RP detects a routing topology change, the appropriate MLS cache entries are deleted in the MLS-SE. The techniques for handling route and access list changes apply to both the RSM and directly attached external routers.

MLS-RP

(MLS-SE)

1200

3

Host A Host B

Layer 3-switched packets

With the MLS entry from Host A to B established, the Layer 3 traffic for this flow is switched directly insidethe Catalyst switch without going to the router

Multilayer Switching OverviewIntroduction to IP Multicast MLS


Restrictions on Using IP Router Commands with MLS EnabledThe following Cisco IOS commands affect MLS on your router:

• clear ip-route—Clears all MLS cache entries for all Catalyst 5000 series switches performing Layer 3 switching for this MLS-RP.

• ip routing—The no form purges all MLS cache entries and disables MLS on this MLS-RP.

• ip security (all forms of this command)—Disables MLS on the interface.

• ip tcp compression-connections—Disables MLS on the interface.

• ip tcp header-compression—Disables MLS on the interface.

General GuidelinesThe following is a list of general guidelines to enabling MLS:

• When you enable MLS, the RSM or externally attached router continues to handle all non-IP protocols while offloading the switching of IP packets to the MLS-SE.

• Do not confuse MLS with the NetFlow switching supported by Cisco routers. MLS uses both the RSM or directly attached external router and the MLS-SE. With MLS, you are not required to use NetFlow switching on the RSM or directly attached external router; any switching path on the RSM or directly attached external router will work (process, fast, and so on).

Introduction to IP Multicast MLSThe IP multicast MLS feature provides high-performance, hardware-based, Layer 3 switching of IP multicast traffic for routers connected to LAN switches.

An IP multicast flow is a unidirectional sequence of packets between a multicast source and the members of a destination multicast group. Flows are based on the IP address of the source device and the destination IP multicast group address.

IP multicast MLS switches IP multicast data packet flows between IP subnets using advanced, ASIC switching hardware, thereby off loading processor-intensive, multicast packet routing from network routers.

The packet forwarding function is moved onto the connected Layer 3 switch whenever a supported path exists between a source and members of a multicast group. Packets that do not have a supported path to reach their destinations are still forwarded in software by routers. Protocol Independent Multicast (PIM) is used for route determination.

IP Multicast MLS Network TopologyIP multicast MLS requires specific network topologies to function correctly. In each of these topologies, the source traffic is received on the switch, traverses a trunk link to the router, and returns to the switch over the same trunk link to reach the destination group members. The basic topology consists of a switch and an internal or external router connected through an ISL or 802.1Q trunk link.

Figure 67 shows this basic configuration before and after IP multicast MLS is deployed (assuming a completely switched flow). The topology consists of a switch, a directly connected external router, and multiple IP subnetworks (VLANs).



The network in the upper diagram in Figure 67 does not have the IP multicast MLS feature enabled. Note the arrows from the router to each multicast group in each VLAN. In this case, the router must replicate the multicast data packets to the multiple VLANs. The router can be easily overwhelmed with forwarding and replicated multicast traffic if the input rate or the number of outgoing interfaces increases.

As shown in the lower diagram in Figure 67, this potential problem is prevented by having the switch hardware forward the multicast data traffic. (Multicast control packets are still moving between the router and switch.)

Figure 67 Basic IP Multicast MLS Network Topology

Benefits of multicast MLS are as follows:

• Improves throughput—The improves throughput feature improves the router’s multicast Layer 3 forwarding and replication throughput.

• Reduces load on router—If the router must replicate many multicast packets to many VLANs, it can be overwhelmed as the input rate and number of outgoing interfaces increase. Configuring the switch to replicate and forward the multicast flow reduces the demand on the router.

Router

Trunk linkVLANs 100, 200, 300


G1member

G1member

G1member

G1 source

VLAN 300

VLAN 200

VLAN 100

Router(MMLS-RP)

G1member

G1member

G1member

G1source

VLAN 300

VLAN 200

VLAN 100

Switch

Switch(MMLS-SE)

1895

2

Before IP multicast MLS

After IP multicast MLS(completely switched)



• Provides IP multicast scalability—If you need high throughput of multicast traffic, install a Catalyst 5000 series switch and configure the Provides IP Multicast Scalability feature. By reducing the load on your router, the router can accommodate more multicast flows.

• Provides meaningful flow statistics—IP multicast MLS provides flow statistics that can be used to administer, plan, and troubleshoot networks.

IP Multicast MLS ComponentsAn IP multicast MLS network topology has two components:

• Multicast MLS-Switching Engine (MMLS-SE)—For example, a Catalyst 5000 series switch with hardware that supports IP multicast MLS. The MMLS-SE provides Layer 3 LAN-switching services.

• Multicast MLS-Route Processor (MMLS-RP)—Routing platform running Cisco IOS software that supports IP multicast MLS. The MMLS-RP interacts with the IP multicast routing software and updates the MLS cache in the MMLS-SE. When you enable IP multicast MLS, the MMLS-RP continues to handle all non-IP-multicast traffic while off loading IP multicast traffic forwarding to the MMLS-SE.

Layer 2 Multicast Forwarding TableThe MMLS-SE uses the Layer 2 multicast forwarding table to determine on which ports Layer 2 multicast traffic should be forwarded (if any). The Layer 2 multicast forwarding table is populated by enabling CGMP, IGMP snooping, or GMRP on the switch. These entries map the destination multicast MAC address to outgoing switch ports for a given VLAN.

Layer 3 Multicast MLS CacheThe MMLS-SE maintains the Layer 3 MLS cache to identify individual IP multicast flows. Each entry is of the form {source IP, destination group IP, source VLAN}. The maximum MLS cache size is 128K and is shared by all MLS processes on the switch (such as IP unicast MLS and IPX MLS). However, if the total of cache entries exceeds 32K, there is increased probability that a flow will not be switched by the MMLS-SE and will get forwarded to the router.

The MMLS-SE populates the MLS cache using information learned from the routers participating in IP multicast MLS. The router and switch exchange information using the multicast MLSP.

Whenever the router receives traffic for a new flow, it updates its multicast routing table and forwards the new information to the MMLS-SE using multicast MLSP. In addition, if an entry in the multicast routing table is aged out, the router deletes the entry and forwards the updated information to the MMLS-SE.

The MLS cache contains flow information for all active multilayer switched flows. After the MLS cache is populated, multicast packets identified as belonging to an existing flow can be Layer 3 switched based on the cache entry for that flow. For each cache entry, the MMLS-SE maintains a list of outgoing interfaces for the destination IP multicast group. The MMLS-SE uses this list to determine on which VLANs traffic to a given multicast flow should be replicated.



IP Multicast MLS Flow MaskIP multicast MLS supports a single flow mask, source destination vlan. The MMLS-SE maintains one multicast MLS cache entry for each {source IP, destination group IP, source VLAN}. The multicast source destination vlan flow mask differs from the IP unicast MLS source destination ip flow mask in that, for IP multicast MLS, the source VLAN is included as part of the entry. The source VLAN is the multicast Reverse Path Forwarding (RPF) interface for the multicast flow.

Layer 3-Switched Multicast Packet RewriteWhen a multicast packet is Layer 3-switched from a multicast source to a destination multicast group, the MMLS-SE performs a packet rewrite based on information learned from the MMLS-RP and stored in the multicast MLS cache.

For example, if Server A sends a multicast packet addressed to IP multicast group G1 and members of group G1 are on VLANs other than the source VLAN, the MMLS-SE must perform a packet rewrite when it replicates the traffic to the other VLANs (the switch also bridges the packet in the source VLAN).

When the MMLS-SE receives the multicast packet, it is formatted similarly to the sample shown in Table 38.

The MMLS-SE rewrites the packet as follows:

• Changes the source MAC address in the Layer 2 frame header from the MAC address of the server to the MAC address of the MMLS-RP (this MAC address is stored in the multicast MLS cache entry for the flow)

• Decrements the IP header Time to Live (TTL) by one and recalculates the IP header checksum

The result is a rewritten IP multicast packet that appears to have been routed by the router. The MMLS-SE replicates the rewritten packet onto the appropriate destination VLANs, where it is forwarded to members of IP multicast group G1.

After the MMLS-SE performs the packet rewrite, the packet is formatted as shown in Table 39:

Table 38 Layer 3-Switched Multicast Packet Header

Frame Header IP Header Payload

Destination Source Destination Source TTL Checksum Data Checksum

Group G1 MAC

Server A MAC

Group G1 IP Server A IP n calculation1

Table 39 Layer 3-Switched Multicast Packet Header with Rewrite

Frame Header IP Header Payload

Destination Source Destination Source TTL Checksum Data Checksum

Group G1 MAC

MMLS-RP MAC

Group G1 IP Server A IP n – 1 calculation2

Multilayer Switching OverviewIntroduction to IPX MLS


Partially and Completely Switched FlowsWhen at least one outgoing router interface for a given flow is multilayer switched, and at least one outgoing interface is not multilayer switched, that flow is considered partially switched. When a partially switched flow is created, all multicast traffic belonging to that flow still reaches the router and is software forwarded on those outgoing interfaces that are not multilayer switched.

A flow might be partially switched instead of completely switched in the following situations:

• Some multicast group destinations are located across the router (not all multicast traffic is received and sent on subinterfaces of the same trunk link).

• The router is configured as a member of the IP multicast group (using the ip igmp join-group interface command) on the RPF interface of the multicast source.

• The router is the first-hop router to the source in PIM sparse mode (in this case, the router must send PIM-register messages to the rendezvous point [RP]).

• Multicast TTL threshold or multicast boundary is configured on an outgoing interface for the flow.

• Multicast helper is configured on the RPF interface for the flow and multicast to broadcast translation is required.

• Access list restrictions are configured on an outgoing interface (see the “Access List Restrictions and Guidelines” section in the “Configuring Multicast Multilayer Switching” chapter).

• Integrated routing and bridging (IRB) is configured on the ingress interface.

• An output rate limit is configured on an outgoing interface.

• Multicast tag switching is configured on an outgoing interface.

When all the outgoing router interfaces for a given flow are multilayer switched, and none of the situations described applies to the flow, that flow is considered completely switched. When a completely switched flow is created, the MMLS-SE prevents multicast traffic bridged on the source VLAN for that flow from reaching the MMLS-RP interface in that VLAN, reducing the load on the router.

One consequence of a completely switched flow is that the router cannot record multicast statistics for that flow. Therefore, the MMLS-SE periodically sends multicast packet and byte count statistics for all completely switched flows to the router using multicast MLSP. The router updates the corresponding multicast routing table entry and resets the expiration timer for that multicast route.

Introduction to IPX MLSThe IPX MLS feature provides high-performance, hardware-based, Layer 3 switching for LAN switches. IPX data packet flows are switched between networks, off loading processor-intensive packet routing from network routers.

Whenever a partial or complete switched path exists between two hosts, packet forwarding occurs on Layer 3 switches. Packets without such a partial or complete switched path are still forwarded by routers to their destinations. Standard routing protocols such as RIP, Enhanced IGRP, and NetWare Link Services Protocol (NLSP) are used for route determination.

IPX MLS also allows you to debug and trace flows in your network. Use MLS explorer packets to identify which switch is handling a particular flow. These packets aid you in path detection and troubleshooting.



IPX MLS ComponentsAn IPX MLS network topology has the following components:

• MLS-SE—For example, a Catalyst 5000 series switch with the Netflow Feature Card (NFFC II). The MLS-SE provides Layer 3 LAN-switching services.

• MLS-RP—For example, a Catalyst 5000 series RSM or an externally connected Cisco 4500, 4700, 7200, or 7500 series router with software that supports MLS. The MLS-RP provides Cisco IOS-based multiprotocol routing, network services, and central configuration and control for the switches.

• MLSP—The protocol running between the MLS-SE and MLS-RP that enables MLS.

IPX MLS FlowsLayer 3 protocols such as IP and IPX are connectionless—they deliver every packet independently of every other packet. However, actual network traffic consists of many end-to-end conversations, or flows, between users or applications.

A flow is a unidirectional packet sequence between a particular source and destination that share identical protocol and network-layer information. Communication flows from a client to a server and from the server to the client are distinct.

Flows are based only on Layer 3 addresses. If a destination IPX address identifies a flow, then IPX traffic from multiple users or applications to a particular destination can be carried on a single flow.

Layer 3-switched flows appear in the MLS cache, a special Layer 3 switching table is maintained by the NFFC II. The cache contains traffic statistics entries that are updated in tandem with packet switching. After the MLS cache is created, packets identified as belonging to an existing flow can be Layer 3 switched. The MLS cache maintains flow information for all active flows.

MLS CacheThe MLS-SE maintains a cache for IPX MLS flows and maintains statistics for each flow. An IPX MLS cache entry is created for the initial packet of each flow. Upon receipt of a packet that does not match any flow in the MLS cache, a new IPX MLS entry is created.

The state and identity of the flow are maintained while packet traffic is active; when traffic for a flow ceases, the entry ages out. You can configure the aging time for IPX MLS entries kept in the MLS cache. If an entry is not used for the specified period of time, the entry ages out and statistics for that flow can be exported to a flow collector application.

The maximum MLS cache size is 128,000 entries. However, an MLS cache larger than 32,000 entries increases the probability that a flow will not be switched by the MLS-SE and will get forwarded to the router.

Note The number of active flows that can be switched using the MLS cache depends on the type of access lists configured on MLS router interfaces (which determines the flow mask). See the “Flow Mask Modes” section later in this document.



Flow Mask ModesTwo flow mask modes—destination mode and destination-source mode—determine how IPX MLS entries are created for the MLS-SE.

You determine the mode when you configure IPX access lists on the MLS-RP router interfaces. Each MLS-RP sends MLSP messages about its flow mask to the MLS-SE, which performs Layer 3 switching. The MLS-SE supports only the most specific flow mask for its MLS-RPs. If it detects more than one mask, it changes to the most specific mask and purges the entire MLS cache. When an MLS-SE exports cached entries, it creates flow records from the most current flow mask mode. Depending on the current mode, some fields in the flow record might not have values. Unsupported fields are filled with a zero (0).

The two modes are described, as follows:

• Destination mode—The least-specific flow mask mode. The MLS-SE maintains one IPX MLS entry for each destination IPX address (network and node). All flows to a given destination IPX address use this IPX MLS entry. Use this mode if no access lists have been configured according to source IPX address on any of the IPX MLS router interfaces. In this mode the destination IPX address of the switched flows is displayed, along with the rewrite information: rewritten destination MAC, rewritten VLAN, and egress port.

• Destination-source mode—The MLS-SE maintains one MLS entry for each destination (network and node) and source (network only) IPX address pair. All flows between a given source and destination use this MLS entry regardless of the IPX sockets. Use this mode if an access list exists on any MLS-RP IPX interfaces that filter on source network.

Note The flow mask mode determines the display of the show mls rp ipx EXEC command. Refer to the Cisco IOS Switching Services Command Reference for details.

Layer 3-Switched Packet RewriteWhen a packet is Layer 3 switched from a source host to a destination host, the switch (MLS-SE) performs a packet rewrite based on information it learned from the router (MLS-RP) and then stored in the MLS cache.

If Host A and Host B are on different VLANs and Host A sends a packet to the MLS-RP to be routed to Host B, the MLS-SE recognizes that the packet was sent to the MAC address of the MLS-RP. The MLS-SE then checks the MLS cache and finds the entry matching the flow in question.

When the MLS-SE receives the packet, it is formatted as shown in Table 40:

Table 40 Layer 3-Switched Packet Header Sent to the MLS-RP

Frame Header Encap IPX Header Payload

Destination Source Length Checksum/ IPX Length/ Transport Control1

1. Transport Control counts the number of times this packet has been routed. If this number is greater than the maximum (the default is 16), then the packet is dropped.

Packet Type

Destination Net/Node/ Socket

Source Net/Node/ Socket

Data PAD/FCS

MLS-RP MAC

Host A MAC

Host B IPX Host A IPX



The MLS-SE rewrites the Layer 2 frame header, changing the destination MAC address to that of Host B and the source MAC address to that of the MLS-RP (these MAC addresses are stored in the IPX MLS cache entry for this flow). The Layer 3 IPX addresses remain the same. The MLS-SE rewrites the switched Layer 3 packets so that they appear to have been routed by a router.

The MLS-SE forwards the rewritten packet to Host B’s VLAN (the destination VLAN is saved in the IPX MLS cache entry) and Host B receives the packet.

After the MLS-SE performs the packet rewrite, the packet is formatted as shown in Table 41:

IPX MLS Operation Figure 68 shows a simple IPX MLS network topology:

• Host A is on the Sales VLAN (IPX address 01.Aa).

• Host B is on the Marketing VLAN (IPX address 03.Bb).

• Host C is on the Engineering VLAN (IPX address 02.Cc).

When Host A initiates a file transfer to Host B, an IPX MLS entry for this flow is created (see the first item in Figure 68’s table). When the MLS-RP forwards the first packet from Host A through the switch to Host B, the MLS-SE stores the MAC addresses of the MLS-RP and Host B in the IPX MLS entry. The MLS-SE uses this information to rewrite subsequent packets from Host A to Host B.

Similarly, a separate IPX MLS entry is created in the MLS cache for the traffic from Host A to Host C, and for the traffic from Host C to Host A. The destination VLAN is stored as part of each IPX MLS entry so that the correct VLAN identifier is used for encapsulating traffic on trunk links.

Table 41 Layer 3-Switched Packet with Rewrite from the MLS-RP

Frame Header Encap IPX Header Payload

Destination Source Length Checksum/ IPX Length/ Transport Control

Packet Type

Destination Net/Node/ Socket

Source Net/Node/ Socket

Data PAD/FCS

Host B MAC MLS-RP MAC

Host B IPX Host A IPX



Figure 68 IPX MLS Example Topology

Standard Access Lists

Note Router interfaces with input access lists or outbound access lists unsupported by MLS cannot participate in IPX MLS. However, you can translate any input access list to an output access list to provide the same effect on the interface.

IPX MLS enforces access lists on every packet of the flow, without compromising IPX MLS performance. The MLS-SE handles permit traffic supported by MLS at wire speed.

Note Access list deny traffic is always handled by the MLS-RP, not the MLS-SE.

The MLS switching path automatically reflects route topology changes and the addition or modification of access lists on the MLS-SE. The techniques for handling route and access list changes apply to both the RSM and directly attached external routers.

For example, for Stations A and B to communicate, Station A sends the first packet to the MLS-RP. If the MLS-RP is configured with an access list to deny access from Station A to Station B, the MLS-RP receives the packet, checks its access list permissions to learn if the packet flow is permitted, and then discards the packet. Because the MLS-SE does not receive the returned first packet for this flow from the MLS-RP, the MLS-SE does not create an MLS cache entry.

Source IPX Address

01.Aa

01.Aa

02.Cc

01.Aa:02.CcData

03.Bb

02.Cc

01.Aa

Dd:Bb

Dd:Cc

Dd:Aa

Marketing

Engineering

Sales

DestinationIPX Address

Rewrite Src/DstMAC Address

DestinationVLAN

RSM

Net 1/Sales

01

MAC = Aa

MAC = Dd

MAC = Bb

MAC = Cc

Net 3/Marketing

03

Net 2/Engineering02

Aa:Dd

01.Aa:02.CcData Dd:Cc

1856

1

Multilayer Switching OverviewGuidelines for External Routers


In contrast, if the MLS-SE is already Layer 3 switching a flow and the access list is created on the MLS-RP, MLSP notifies the MLS-SE, and the MLS-SE immediately purges the affected flow from the MLS cache. New flows are created based on the restrictions imposed by the access list.

Similarly, when the MLS-RP detects a routing topology change, the MLS-SE deletes the appropriate MLS cache entries, and new flows are created based on the new topology.

Guidelines for External RoutersWhen using an external router, follow these guidelines:

• We recommend one directly attached external router per Catalyst 5000 series switch to ensure that the MLS-SE caches the appropriate flow information from both sides of the routed flow.

• You can use Cisco high-end routers (Cisco 7500, 7200, 4500, and 4700 series) for MLS when they are externally attached to the Catalyst 5000 series switch. You can make the attachment with multiple Ethernets (one per subnet), by using Fast Ethernet with the ISL, or with Fast Etherchannel.

• You can connect end hosts through any media (Ethernet, Fast Ethernet, ATM, and FDDI) but the connection between the external router and the Catalyst 5000 series switch must be through standard 10/100 Ethernet interfaces, ISL links, or Fast Etherchannel.

Features That Affect MLSThis section describes how certain features affect MLS.

Access ListsThe following sections describe how access lists affect MLS.

Input Access Lists

Router interfaces with input access lists cannot participate in MLS. If you configure an input access list on an interface, all packets for a flow that are destined for that interface go through the router (even if the flow is allowed by the router it is not Layer 3 switched). Existing flows for that interface get purged and no new flows are cached.

Note Any input access list can be translated to an output access list to provide the same effect on the interface.

Output Access Lists

If an output access list is applied to an interface, the MLS cache entries for that interface are purged. Entries associated with other interfaces are not affected; they follow their normal aging or purging procedures.

Applying an output access list to an interface, when the access list is configured using the log, precedence, tos, or establish keywords, prevents the interface from participating in MLS.

Multilayer Switching OverviewFeatures That Affect MLS


Access List Impact on Flow Masks

Access lists impact the flow mask advertised by an MLS-RP. When no access list on any MLS-RP interface, the flow mask mode is destination-ip (the least specific). When there is a standard access list is on any of the MLS-RP interfaces, the mode is source-destination-ip. When there is an extended access list is on any of the MLS-RP interfaces, the mode is ip-flow (the most specific).

Reflexive Access Lists

Router interfaces with reflexive access lists cannot participate in Layer 3 switching.

IP Accounting Enabling IP accounting on an MLS-enabled interface disables the IP accounting functions on that interface.

Note To collect statistics for the Layer 3-switched traffic, enable NDE.

Data EncryptionMLS is disabled on an interface when the data encryption feature is configured on the interface.

Policy Route MapsMLS is disabled on an interface when a policy route map is configured on the interface.

TCP InterceptWith MLS interfaces enabled, the TCP intercept feature (enabled in global configuration mode) might not work properly. When you enable the TCP intercept feature, the following message is displayed:

Command accepted, interfaces with mls might cause inconsistent behavior.

Network Address TranslationMLS is disabled on an interface when Network Address Translation (NAT) is configured on the interface.

Committed Access RateMLS is disabled on an interface when committed access rate (CAR) is configured on the interface.

Multilayer Switching OverviewFeatures That Affect MLS


Maximum Transmission UnitThe maximum transmission unit (MTU) for an MLS interface must be the default Ethernet MTU, 1500 bytes.

To change the MTU on an MLS-enabled interface, you must first disable MLS on the interface (enter no mls rp ip global configuration command in the interface). If you attempt to change the MTU with MLS enabled, the following message is displayed:

Need to turn off the mls router for this interface first.

If you attempt to enable MLS on an interface that has an MTU value other than the default value, the following message is displayed:

mls only supports interfaces with default mtu size


Configuring IP Multilayer Switching

This chapter describes how to configure your network to perform IP Multilayer Switching (MLS). This chapter contains these sections:

• Configuring and Monitoring MLS

• Configuring NetFlow Data Export

• Multilayer Switching Configuration Examples



Note The information in this chapter is a brief summary of the information contained in the Catalyst 5000 Series Multilayer Switching User Guide. The commands and configurations described in this guide apply only to the devices that provide routing services. Commands and configurations for Catalyst 5000 series switches are documented in the Catalyst 5000 Series Multilayer Switching User Guide. For configuration information for the Catalyst 6000 series switch, see Configuring and Troubleshooting IP MLS on Catalyst 6000 with an MSFC or the “Configuring IP Multilayer Switching” chapter in the Catalyst 6500 Series MSFC (12.x) & PFC Configuration Guide.

Configuring and Monitoring MLS To configure your Cisco router for MLS, perform the tasks described in the following sections. The first section contains a required task; the remaining tasks are optional. To ensure a successful MLS configuration, you must also configure the Catalyst switches in your network. For a full description for the Catalyst 5000 series, see the Catalyst 5000 Series Multilayer Switching User Guide. For a full description for the Catalyst 6000 series, see the “Configuring IP Multilayer Switching” chapter in the Catalyst 6500 Series MSFC (12.x) & PFC Configuration Guide. Only configuration tasks and commands for routers are described in this chapter.

• Configuring MLS on a Router (Required)

• Monitoring MLS (Optional)

Configuring IP Multilayer SwitchingConfiguring and Monitoring MLS


• Monitoring MLS for an Interface (Optional)

• Monitoring MLS Interfaces for VTP Domains (Optional)

Configuring MLS on a RouterTo configure MLS on your router, use the following commands beginning in global configuration mode. Depending upon your configuration, you might not have to perform all the steps in the procedure.

Note The interface-specific commands in this section apply only to Ethernet, Fast Ethernet, VLAN, and Fast Etherchannel interfaces on the Catalyst RSM/Versatile Interface Processor 2 (VIP2) or directly attached external router.

To globally disable MLS on the router, use the following command in global configuration mode:

Command Purpose

Step 1 Router(config)# mls rp ip Globally enables MLSP. MLSP is the protocol that runs between the MLS-SE and the MLS-RP.

Step 2 Router(config)# interface type number Selects a router interface.

Step 3 Router(config-if)# mls rp vtp-domain [domain-name]

Selects the router interface to be Layer 3 switched and then adds that interface to the same VLAN Trunking Protocol (VTP) domain as the switch. This interface is referred to as the MLS interface. This command is required only if the Catalyst switch is in a VTP domain.

Step 4 Router(config-if)# mls rp vlan-id [vlan-id-num]

Assigns a VLAN ID to the MLS interface. MLS requires that each interface has a VLAN ID. This step is not required for RSM VLAN interfaces or ISL-encapsulated interfaces.

Step 5 Router(config-if)# mls rp ip Enables each MLS interface.

Step 6 Router(config-if)# mls rp management-interface

Selects one MLS interface as a management interface. MLSP packets are sent and received through this interface. This can be any MLS interface connected to the switch.

Repeat steps 2 through 5 for each interface that will support MLS.

Command PurposeRouter(config)# no mls rp ip Disables MLS on the router.



Monitoring MLSTo display MLS details including specifics for MLSP, use the following commands in EXEC mode, as needed:

• MLS status (enabled or disabled) for switch interfaces and subinterfaces

• Flow mask used by this MLS-enabled switch when creating Layer 3-switching entries for the router

• Current settings of the keepalive timer, retry timer, and retry count

• MLSP-ID used in MLSP messages

• List of interfaces in all VTP domains that are enabled for MLS

After entering this command, you see this display:

router# show mls rp

multilayer switching is globally enabledmls id is 00e0.fefc.6000mls ip address 10.20.26.64mls flow mask is ip-flow vlan domain name: WBU current flow mask: ip-flow current sequence number: 80709115 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 13:03:19 keepalive timer expires in 9 seconds retry timer not running change timer not running fcp subblock count = 7 1 management interface(s) currently defined: vlan 1 on Vlan1 7 mac-vlan(s) configured for multi-layer switching: mac 00e0.fefc.6000 vlan id(s) 1 10 91 92 93 95 100 router currently aware of following 1 switch(es): switch id 0010.1192.b5ff

Command Purpose

Router# show mls rp Displays MLS details for all interfaces.



Monitoring MLS for an InterfaceTo show MLS information for a specific interface, use the following command in EXEC mode:


router# show mls rp int vlan 10

mls active on Vlan10, domain WBUrouter#

Monitoring MLS Interfaces for VTP DomainsTo show MLS information for a specific VTP domain use the following command in EXEC mode:


router# show mls rp vtp-domain WBU

vlan domain name: WBU current flow mask: ip-flow current sequence number: 80709115 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 13:07:36 keepalive timer expires in 8 seconds retry timer not running change timer not running fcp subblock count = 7 1 management interface(s) currently defined: vlan 1 on Vlan1 7 mac-vlan(s) configured for multi-layer switching: mac 00e0.fefc.6000 vlan id(s) 1 10 91 92 93 95 100 router currently aware of following 1 switch(es): switch id 0010.1192.b5ff

Command PurposeRouter# show mls rp [interface] Displays MLS details for a specific interface.

Command PurposeRouter# show mls rp vtp-domain [domain-name] Displays MLS interfaces for a specific VTP domain.

Configuring IP Multilayer SwitchingConfiguring NetFlow Data Export


Configuring NetFlow Data Export

Note You need to enable NDE only if you will export MLS cache entries to a data collection application.

Perform the task in this section to configure your Cisco router for NDE. To ensure a successful NDE configuration, you must also configure the Catalyst switch. For a full description, see the Catalyst 5000 Series Multilayer Switching User Guide.

Specifying an NDE Address on the RouterTo specify an NDE address on the router, use the following command in global configuration mode:

Multilayer Switching Configuration ExamplesIn these examples, VLAN interfaces 1 and 3 are in VTP domain named Engineering. The management interface is configured on the VLAN 1 interface. Only information relevant to MLS is shown in the following configurations:

• Router Configuration Without Access Lists Example

• Router Configuration with a Standard Access List Example

• Router Configuration with an Extended Access List Example

Router Configuration Without Access Lists ExampleThis sample configuration shows a router configured without access lists on any of the VLAN interfaces. The flow mask is configured to be destination-ip.

router# more system:running-config

Building configuration... Current configuration:...mls rp ip

interface Vlan1 ip address 172.20.26.56 255.255.255.0mls rp vtp-domain Engineering

mls rp management-interface mls rp ip

Command Purpose

Router(config)# mls rp nde-address ip-address Specifies an NDE IP address for the router doing the Layer 3 switching. The router and the Catalyst 5000 series switch use the NDE IP address when sending MLS statistics to a data collection application.

Configuring IP Multilayer SwitchingMultilayer Switching Configuration Examples


interface Vlan2 ip address 172.16.2.73 255.255.255.0

interface Vlan3 ip address 172.16.3.73 255.255.255.0mls rp vtp-domain Engineering

mls rp ip ..end

router#router# show mls rp

multilayer switching is globally enabledmls id is 0006.7c71.8600mls ip address 172.20.26.56mls flow mask is destination-ip

number of domains configured for mls 1vlan domain name: Engineering current flow mask: destination-ip current sequence number: 82078006 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 02:54:21 keepalive timer expires in 11 seconds retry timer not running change timer not running 1 management interface(s) currently defined: vlan 1 on Vlan1 2 mac-vlan(s) configured for multi-layer switching: mac 0006.7c71.8600 vlan id(s) 1 3 router currently aware of following 1 switch(es): switch id 00e0.fe4a.aeff

Router Configuration with a Standard Access List ExampleThis configuration is the same as the previous example but with a standard access list configured on the VLAN 3 interface. The flow mask changes to source-destination-ip.

.interface Vlan3 ip address 172.16.3.73 255.255.255.0 ip access-group 2 outmls rp vtp-domain Engineering

mls rp ip.

router# show mls rp

multilayer switching is globally enabledmls id is 0006.7c71.8600mls ip address 172.20.26.56



mls flow mask is source-destination-ip number of domains configured for mls 1vlan domain name: Engineering current flow mask: source-destination-ip current sequence number: 82078007 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 02:57:31 keepalive timer expires in 4 seconds retry timer not running change timer not running 1 management interface(s) currently defined: vlan 1 on Vlan1 2 mac-vlan(s) configured for multi-layer switching: mac 0006.7c71.8600 vlan id(s) 1 3 router currently aware of following 1 switch(es): switch id 00e0.fe4a.aeff

Router Configuration with an Extended Access List ExampleThis configuration is the same as the previous examples but with an extended access list configured on the VLAN 3 interface. The flow mask changes to ip-flow.

.interface Vlan3 ip address 172.16.3.73 255.255.255.0 ip access-group 101 outmls rp vtp-domain Engineering

mls rp ip.

router# show mls rp

multilayer switching is globally enabledmls id is 0006.7c71.8600mls ip address 172.20.26.56mls flow mask is ip-flow number of domains configured for mls 1vlan domain name: Engineering current flow mask: ip-flow current sequence number: 82078009 current/maximum retry count: 0/10 current domain state: no-change current/next global purge: false/false current/next purge count: 0/0 domain uptime: 03:01:52 keepalive timer expires in 3 seconds retry timer not running change timer not running 1 management interface(s) currently defined:



vlan 1 on Vlan1 2 mac-vlan(s) configured for multi-layer switching: mac 0006.7c71.8600 vlan id(s) 1 3 router currently aware of following 1 switch(es): switch id 00e0.fe4a.aeff


Configuring IP Multicast Multilayer Switching

This chapter describes how to configure your network to perform IP multicast Multilayer Switching (MLS). This chapter contains these sections:

• Prerequisites

• Restrictions

• Configuring and Monitoring IP Multicast MLS

• IP Multicast MLS Configuration Examples




PrerequisitesThe following prerequisites are necessary before MLS can function:

• A VLAN interface must be configured on both the switch and the router. For information on configuring inter-VLAN routing on the RSM or an external router, refer to the Catalyst 5000 Software Configuration Guide.

• IP multicast MLS must be configured on the switch. For procedures on this task, refer to the “Configuring IP Multicast Routing” chapter in the Cisco IOS IP Routing Configuration Guide.

• IP multicast routing and PIM must be enabled on the router. The minimal steps to configure them are described in the “Configuring and Monitoring IP Multicast MLS” section later in this document. For detailed information on configuring IP multicast routing and PIM, refer to the Cisco IOS IP Routing Configuration Guide.

Configuring IP Multicast Multilayer SwitchingRestrictions


RestrictionsYou must also configure the Catalyst 5000 series switch in order for IP multicast MLS to function on the router.

The restrictions in the following sections apply to IP multicast MLS on the router:

• Router Configuration Restrictions

• External Router Guidelines

• Access List Restrictions and Guidelines

Router Configuration RestrictionsIP multicast MLS does not work on internal or external routers in the following situations:

• If IP multicast MLS is disabled on the RPF interface for the flow (using the no mls rp ip multicast interface configuration command).

• For IP multicast groups that fall into these ranges (where * is in the range from 0 to 255):

– 224.0.0.* through 239.0.0.*

– 224.128.0.* through 239.128.0.*

Note Groups in the 224.0.0.* range are reserved for routing control packets and must be flooded to all forwarding ports of the VLAN. These addresses map to the multicast MAC address range 01-00-5E-00-00-xx, where xx is in the range from 0 to 0xFF.

• For PIM auto-RP multicast groups (IP multicast group addresses 224.0.1.39 and 224.0.1.40).

• For flows that are forwarded on the multicast shared tree (that is, {*, G, *} forwarding) when the interface or group is running PIM sparse mode.

• If the shortest path tree (SPT) bit for the flow is cleared when running PIM sparse mode for the interface or group.

• When an input rate limit is applied on an RPF interface.

• For any RPF interface with access lists applied (for detailed information, see the “Access List Restrictions and Guidelines” section later in this document).

• For any RPF interface with multicast boundary configured.

• For packets that require fragmentation and packets with IP options. However, packets in the flow that are not fragmented or that do not specify IP options are multilayer switched.

• On external routers, for source traffic received at the router on non-ISL or non-802.1Q interfaces.

• For source traffic received on tunnel interfaces (such as MBONE traffic).

• For any RPF interface with multicast tag switching enabled.

Configuring IP Multicast Multilayer SwitchingConfiguring and Monitoring IP Multicast MLS


External Router GuidelinesFollow these guidelines when using an external router:

• The connection to the external router must be over a single ISL or 802.1Q trunk link with subinterfaces (using appropriate encapsulation type) configured.

• A single external router can serve as the MMLS-RP for multiple switches, provided each switch connects to the router through a separate ISL or 802.1Q trunk link.

• If the switch connects to a single router through multiple trunk links, IP multicast MLS is supported on one of the links only. You must disable IP multicast MLS on the redundant links using the no mls rp ip multicast interface configuration command.

• You can connect end hosts (source or multicast destination devices) through any media (Ethernet, Fast Ethernet, ATM, and FDDI), but the connection between external routers and the switch must be through Fast Ethernet or Gigabit Ethernet interfaces.

Access List Restrictions and GuidelinesThe following restrictions apply when using access lists on interfaces participating in IP multicast MLS:

• All standard access lists are supported on any interface. The flow is multilayer switched on all interfaces on which the traffic for the flow is allowed by the access list.

• Layer 4 port-based extended IP input access lists are not supported. For interfaces with these access lists applied, no flows are multilayer switched.

• Extended access lists on the RPF interface that specify conditions other than Layer 3 source, Layer 3 destination, and ip protocol are not multilayer switched.

For example, if the following input access list is applied to the RPF interface for a group of flows, no flows will be multilayer switched even though the second entry permits all IP traffic (because the protocol specified in the first entry is not ip):

Router(config)# access-list 101 permit udp any anyRouter(config)# access-list 101 permit ip any any

If the following input access list is applied to the RPF interface for a group of flows, all flows except the {s1, g1} flow are multilayer switched (because the protocol specified in the entry for {s1, g1} is not ip):

Router(config)# access-list 101 permit udp s1 g1Router(config)# access-list 101 permit ip any any

Configuring and Monitoring IP Multicast MLS To configure your Cisco router for IP multicast MLS, perform the tasks described in the following sections. The first two sections contain required tasks; the remaining tasks are optional. To ensure a successful multicast MLS configuration, you must also configure the Catalyst switches in your network. For a full description, refer to the Catalyst 5000 Series Multilayer Switching User Guide.

• Enabling IP Multicast Routing (Required)

• Enabling IP PIM (Required)

• Enabling IP Multicast MLS (Optional, this is a required task if you disabled it.)

• Specifying a Management Interface (Optional)

Configuring IP Multicast Multilayer SwitchingConfiguring and Monitoring IP Multicast MLS


For examples of IP multicast MLS configurations, see the “IP Multicast MLS Configuration Examples” section later in this document.

Enabling IP Multicast RoutingYou must enable IP multicast routing globally on the MMLS-RPs before you can enable IP multicast MLS on router interfaces. To enable IP multicast routing on the router, use the following command in router configuration mode:

Note This section describes only how to enable IP multicast routing on the router. For detailed IP multicast configuration information, refer to the “Configuring IP Multicast Routing” chapter in the Cisco IOS IP Routing Configuration Guide.

Enabling IP PIM You must enable PIM on the router interfaces connected to the switch before IP multicast MLS will function on those router interfaces. To do so, use the following commands beginning in interface configuration mode:

Note This section describes only how to enable PIM on router interfaces. For detailed PIM configuration information, refer to the “Configuring IP Multicast Routing” chapter in the Cisco IOS IP Routing Configuration Guide.

Enabling IP Multicast MLSIP multicast MLS is enabled by default when you enable PIM on the interface. Perform this task only if you disabled IP multicast MLS and you want to reenable it. To enable IP multicast MLS on an interface, use the following command in interface configuration mode:

Command Purpose

Router(config)# ip multicast-routing Enables IP multicast routing globally.

Command Purpose

Step 1 Router(config)# interface type number Configures an interface.

Step 2 Router(config-if)# ip pim {dense-mode | sparse-mode | sparse-dense-mode}

Enables PIM on the interface.

Command Purpose

Router(config-if)# mls rp ip multicast Enables IP multicast MLS on an interface.

Configuring IP Multicast Multilayer SwitchingIP Multicast MLS Configuration Examples


Specifying a Management InterfaceWhen you enable IP multicast MLS, the subinterface (or VLAN interface) that has the lowest VLAN ID and is active (in the “up” state) is automatically selected as the management interface. The one-hop protocol Multilayer Switching Protocol (MLSP) is used between a router and a switch to pass messages about hardware-switched flows. MLSP packets are sent and received on the management interface. Typically, the interface in VLAN 1 is chosen (if that interface exists). Only one management interface is allowed on a single trunk link.

In most cases, we recommend that the management interface be determined by default. However, you can optionally specify a different router interface or subinterface as the management interface. We recommend using a subinterface with minimal data traffic so that multicast MLSP packets can be sent and received more quickly.

If the user-configured management interface goes down, the router uses the default interface (the active interface with the lowest VLAN ID) until the user-configured interface comes up again.

To change the default IP multicast MLS management interface, use the following command in interface configuration mode:

Monitoring and Maintaining IP Multicast MLSTo monitor and maintain an IP multicast MLS network, use the following commands in EXEC modes, as needed:

IP Multicast MLS Configuration ExamplesThe following sections contain example IP multicast MLS implementations. These examples include the switch configurations, although switch commands are not documented in this router publication. Refer to the Catalyst 5000 Command Reference for that information.

• Basic IP Multicast MLS Network Examples

• Complex IP Multicast MLS Network Examples

Command PurposeRouter(config-if)# mls rp ip multicast management-interface Configures an interface as the IP multicast MLS

management interface.

Command PurposeRouter# show ip mroute [group-name | group-address [source]] Displays hardware switching state for outgoing

interfaces.

Router# show ip pim interface [type number] [count] Displays PIM interface information.

Router# show mls rp ip multicast [locate] [group [source] [vlan-id]] | [statistics] | [summary]

Displays Layer 3 switching information.



Basic IP Multicast MLS Network ExamplesThis example consists of the following sections:

• Network Topology Example

• Operation Before IP Multicast MLS Example

• Operation After IP Multicast MLS Example

• Router Configuration

• Switch Configuration

Network Topology Example

Figure 69 shows a basic IP multicast MLS example network topology.

Figure 69 Example Network: Basic IP Multicast MLS

The network is configured as follows:

• There are three VLANs (IP subnetworks): VLANs 10, 20, and 30.

• The multicast source for group G1 belongs to VLAN 10.

• Hosts A, C, and D have joined IP multicast group G1.

• Port 1/2 on the MMLS-SE is connected to interface fastethernet2/0 on the MMLS-RP.

• The link between the MMLS-SE and the MMLS-RP is configured as an ISL trunk.

• The subinterfaces on the router interface have these IP addresses:

– fastethernet2/0.10: 10.1.10.1 255.255.255.0 (VLAN 10)



A

D

B C


Router(MMLS-RP)

VLAN 1010.1.10.0/24

G1 source

G1

G1

G1

VLAN 2010.1.20.0/24

VLAN 3010.1.30.0/24

Switch(MMLS-SE)

1850

1



Operation Before IP Multicast MLS Example

Without IP multicast MLS, when the G1 source (on VLAN 10) sends traffic destined for IP multicast group G1, the switch forwards the traffic (based on the Layer 2 multicast forwarding table entry generated by the IGMP snooping, CGMP, or GMRP multicast service) to Host A on VLAN 10 and to the router subinterface in VLAN 10.

The router receives the multicast traffic on its incoming subinterface for VLAN 10, checks the multicast routing table, and replicates the traffic to the outgoing subinterfaces for VLANs 20 and 30. The switch receives the traffic on VLANs 20 and 30 and forwards the traffic received on these VLANs to the appropriate switch ports, again based on the contents of the Layer 2 multicast forwarding table.

Operation After IP Multicast MLS Example

After IP multicast MLS is implemented, when the G1 source sends traffic destined for multicast group G1, the MMLS-SE checks its Layer 3 multicast MLS cache and recognizes that the traffic belongs to a multicast MLS flow. The MMLS-SE forwards the traffic to Host A on VLAN 10 based on the multicast forwarding table, but does not forward the traffic to the router subinterface in VLAN 10 (assuming a completely switched flow).

For each multicast MLS cache entry, the switch maintains a list of outgoing interfaces for the destination IP multicast group. The switch replicates the traffic on the appropriate outgoing interfaces (VLANs 20 and 30) and then forwards the traffic on each VLAN to the destination hosts (using the Layer 2 multicast forwarding table). The switch performs a packet rewrite for the replicated traffic so that the packets appear to have been routed by the appropriate router subinterface.

If not all the router subinterfaces are eligible to participate in IP multicast MLS, the switch must forward the multicast traffic to the router subinterface in the source VLAN (in this case, VLAN 10). In this situation, on those subinterfaces that are ineligible, the router performs multicast forwarding and replication in software, in the usual manner. On those subinterfaces that are eligible, the switch performs multilayer switching.

Note On the MMLS-RP, the IP multicast MLS management interface is user-configured to the VLAN 30 subinterface. If this interface goes down, the system will revert to the default management interface (in this case, the VLAN 10 subinterface).

Router Configuration

The following is an example configuration of IP multicast MLS on the router:

ip multicast-routinginterface fastethernet2/0.10encapsulation isl 10ip address 10.1.10.1 255.255.255.0ip pim dense-mode

interface fastethernet2/0.20encapsulation isl 20ip address 10.1.20.1 255.255.255.0ip pim dense-mode

interface fastethernet2/0.30encapsulation isl 30ip address 10.1.30.1 255.255.255.0 ip pim dense-modemls rp ip multicast management-interface



You will receive the following message informing you that you changed the management interface:

Warning: MLS Multicast management interface is now Fa2/0.30

Switch Configuration

The following example shows how to configure the switch (MMLS-SE):

Console> (enable) set trunk 1/2 on islPort(s) 1/2 trunk mode set to on.Port(s) 1/2 trunk type set to isl.Console> (enable) set igmp enableIGMP feature for IP multicast enabledConsole> (enable) set mls multicast enableMultilayer Switching for Multicast is enabled for this device.Console> (enable) set mls multicast include 10.1.10.1Multilayer switching for multicast is enabled for router 10.1.10.1.

Complex IP Multicast MLS Network ExamplesThis example consists of the following sections:

• Network Topology Example

• Operation Before IP Multicast MLS Example

• Operation After IP Multicast MLS Example

• Router A (MMLS-RP) Configuration

• Router B (MMLS-RP) Configuration

• Switch A (MMLS-SE) Configuration

• Switch B Configuration

• Switch C Configuration



Network Topology Example

Figure 70 shows a more complex IP multicast MLS example network topology.

Figure 70 Complex IP Multicast MLS Example Network


• There are four VLANs (IP subnetworks): VLANs 1, 10, 20, and 30 (VLAN 1 is used only for management traffic, not multicast data traffic).

• The G1 multicast source belongs to VLAN 10.

• Hosts A, C, D, and E have joined IP multicast group G1.

• Switch A is the MMLS-SE.

• Router A and Router B are both operating as MMLS-RPs.

• Port 1/1 on the MMLS-SE is connected to interface fastethernet1/0 on Router A.

• Port 1/2 on the MMLS-SE is connected to interface fastethernet2/0 on Router B.

• The MMLS-SE is connected to the MMLS-RPs through ISL trunk links.

• The trunk link to Router A carries VLANs 1, 10, and 20.

• The trunk link to Router B carries VLANs 1, 10, and 30.

• The subinterfaces on the Router A interface have these IP addresses:




• The subinterfaces on the Router B interface have these IP addresses:




Router A(MMLS-RP)

Router B(MMLS-RP)

ISL trunks VLANs 10, 30VLANs 10, 20

Switch A(MMLS-SE)

VLAN 20172.20.20.0/24

VLAN 30172.20.30.0/24

VLAN 10172.20.10.0/24

C

A B D E F

G1 G1

G1

G1

G1 source

1895

5

Switch B Switch C



• The default IP multicast MLS management interface is used on both MMLS-RPs (VLAN 1).

• Port 1/3 on the MMLS-SE is connected to Switch B through an ISL trunk link carrying all VLANs.

• Port 1/4 on the MMLS-SE is connected to Switch C through an ISL trunk link carrying all VLANs.

• Switch B and Switch C perform Layer 2 switching functions only.

Operation Before IP Multicast MLS Example

Without IP multicast MLS, when Server A (on VLAN 10) sends traffic destined for IP multicast group G1, Switch B forwards the traffic (based on the Layer 2 multicast forwarding table entry) to Host A on VLAN 10 and to Switch A. Switch A forwards the traffic to the Router A and Router B subinterfaces in VLAN 10.

Router A receives the multicast traffic on its incoming subinterface for VLAN 10, checks the multicast routing table, and replicates the traffic to the outgoing subinterface for VLAN 20. Router B receives the multicast traffic on its incoming interface for VLAN 10, checks the multicast routing table, and replicates the traffic to the outgoing subinterface for VLAN 30.

Switch A receives the traffic on VLANs 20 and 30. Switch A forwards VLAN 20 traffic to the appropriate switch ports (in this case, to Host C), based on the contents of the Layer 2 multicast forwarding table. Switch A forwards the VLAN 30 traffic to Switch C.

Switch C receives the VLAN 30 traffic and forwards it to the appropriate switch ports (in this case, Hosts D and E) using the multicast forwarding table.

Operation After IP Multicast MLS Example

After IP multicast MLS is implemented, when Server A sends traffic destined for multicast group G1, Switch B forwards the traffic (based on the Layer 2 multicast forwarding table entry) to Host A on VLAN 10 and to Switch A.

Switch A checks its Layer 3 multicast MLS cache and recognizes that the traffic belongs to a multicast MLS flow. Switch A does not forward the traffic to the router subinterfaces in VLAN 10 (assuming a completely switched flow). Instead, Switch A replicates the traffic on the appropriate outgoing interfaces (VLANs 20 and 30).

VLAN 20 traffic is forwarded to Host C and VLAN 30 traffic is forwarded to Switch C (based on the contents of the Layer 2 multicast forwarding table). The switch performs a packet rewrite for the replicated traffic so that the packets appear to have been routed by the appropriate router subinterface.

Switch C receives the VLAN 30 traffic and forwards it to the appropriate switch ports (in this case, Hosts D and E) using the multicast forwarding table.

If not all the router subinterfaces are eligible to participate in IP multicast MLS, the switch must forward the multicast traffic to the router subinterfaces in the source VLAN (in this case, VLAN 10). In this situation, on those subinterfaces that are ineligible, the routers perform multicast forwarding and replication in software in the usual manner. On those subinterfaces that are eligible, the switch performs multilayer switching.

Note On both MMLS-RPs, no user-configured IP multicast MLS management interface is specified. Therefore, the VLAN 1 subinterface is used by default.



Router A (MMLS-RP) Configurationip multicast-routinginterface fastethernet1/0.1encapsulation isl 1ip address 172.20.1.1 255.255.255.0



Router B (MMLS-RP) Configurationip multicast-routinginterface fastethernet1/0.1encapsulation isl 1ip address 172.20.1.2 255.255.255.0



Switch A (MMLS-SE) ConfigurationConsole> (enable) set vlan 10Vlan 10 configuration successfulConsole> (enable) set vlan 20Vlan 20 configuration successfulConsole> (enable) set vlan 30Vlan 30 configuration successfulConsole> (enable) set trunk 1/1 on islPort(s) 1/1 trunk mode set to on.Port(s) 1/1 trunk type set to isl.Console> (enable) set trunk 1/2 on islPort(s) 1/2 trunk mode set to on.Port(s) 1/2 trunk type set to isl.Console> (enable) set trunk 1/3 desirable islPort(s) 1/3 trunk mode set to desirable.Port(s) 1/3 trunk type set to isl.Console> (enable) set trunk 1/4 desirable islPort(s) 1/4 trunk mode set to desirable.Port(s) 1/4 trunk type set to isl.Console> (enable) set igmp enableIGMP feature for IP multicast enabledConsole> (enable) set mls multicast enableMultilayer Switching for Multicast is enabled for this device.Console> (enable) set mls multicast include 172.20.10.1Multilayer switching for multicast is enabled for router 172.20.10.1.Console> (enable) set mls multicast include 172.20.10.100Multilayer switching for multicast is enabled for router 172.20.10.100.Console> (enable)



Switch B Configuration

The following example shows how to configure Switch B assuming VLAN Trunking Protocol (VTP) is used for VLAN management:

Console> (enable) set igmp enableIGMP feature for IP multicast enabledConsole> (enable)

Switch C Configuration

The following example shows how to configure Switch C assuming VTP is used for VLAN management:

Console> (enable) set igmp enableIGMP feature for IP multicast enabledConsole> (enable)


Configuring IPX Multilayer Switching

This chapter describes how to configure your network to perform IPX Multilayer Switching (MLS). This chapter contains these sections:

• Prerequisites

• Restrictions

• IPX MLS Configuration Task List

• Troubleshooting Tips

• Monitoring and Maintaining IPX MLS on the Router

• IPX MLS Configuration Examples




PrerequisitesThe following prerequisites must be met before IPX MLS can function:

• A VLAN interface must be configured on both the switch and the router. For information on configuring inter-VLAN routing on the RSM or external router, refer to the Catalyst 5000 Software Configuration Guide, Release 5.1.

• IPX MLS must be configured on the switch. For more information refer to the Catalyst 5000 Software Configuration Guide, Release 5.1 and the Catalyst 5000 Command Reference, Release 5.1.

IPX MLS must be enabled on the router. The minimal configuration steps are described in the section “IPX MLS Configuration Tasks.” For more details on configuring IPX routing, refer to the Cisco IOS AppleTalk and Novell IPX Configuration Guide.

Configuring IPX Multilayer SwitchingRestrictions


RestrictionsThis section describes restrictions that apply to configuring IPX MLS on the router.

General Configuration GuidelinesBe aware of the following restrictions:

• You must configure the Catalyst 5000 series switch for IPX MLS to work.

• When you enable IPX MLS, the RSM or externally attached router continues to handle all non-IPX protocols, while offloading the switching of IPX packets to the MLS-SE.

• Do not confuse IPX MLS with NetFlow switching supported by Cisco routers. IPX MLS requires both the RSM or directly attached external router and the MLS-SE, but not NetFlow switching on the RSM or directly attached external router. Any switching path on the RSM or directly attached external router will function (process, fast, optimum, and so on).

External Router GuidelinesWhen using an external router, use the following guidelines:

• Use one directly attached external router per switch to ensure that the MLS-SE caches the appropriate flow information from both sides of the routed flow.

• Use Cisco high-end routers (Cisco 4500, 4700, 7200, and 7500 series) for IPX MLS when they are externally attached to the switch. Make the attachment with multiple Ethernet connections (one per subnet) or by using Fast or Gigabit Ethernet with Inter-Switch Link (ISL) or IEEE 802.1Q encapsulation.

• Connect end hosts through any media (Ethernet, Fast Ethernet, ATM, and FDDI), but connect the external router and the switch only through standard 10/100 Ethernet interfaces, ISL, or IEEE 802.1Q links.

Access List Restrictions The following restrictions apply when you use access lists on interfaces that participate in IPX MLS:

• Input access lists—Router interfaces with input access lists cannot participate in IPX MLS. If you configure an input access list on an interface, no packets inbound or outbound for that interface are Layer 3 switched, even if the flow is not filtered by the access list. Existing flows for that interface are purged, and no new flows are cached.

Note You can translate input access lists to output access lists to provide the same effect on the interface.

Configuring IPX Multilayer SwitchingIPX MLS Configuration Task List


• Output access lists—When an output access list is applied to an interface, the IPX MLS cache entries for that interface are purged. Entries associated with other interfaces are not affected; they follow their normal aging or purging procedures.

Applying access lists that filter according to packet type, source node, source socket, or destination socket prevents the interface from participating in IPX MLS.

Applying access lists that use the log option prevents the interface from participating in IPX MLS.

• Access list impact on flow masks—Access lists impact the flow mask mode advertised to the MLS-SE by an MLS-RP. If no access list has been applied on any MLS-RP interface, the flow mask mode is destination-ipx (the least specific) by default. If an access list that filters according to the source IPX network has been applied, the mode is source-destination-ipx by default.

Restrictions on Interaction of IPX MLS with Other FeaturesIPX MLS affects other Cisco IOS software features as follows:

• IPX accounting—IPX accounting cannot be enabled on an IPX MLS-enabled interface.

• IPX EIGRP—MLS is supported for EIGRP interfaces if the Transport Control (TC) maximum is set to a value greater than the default (16).

Restriction on Maximum Transmission Unit SizeIn IPX the two endpoints of communication negotiate the maximum transmission unit (MTU) to be used. MTU size is limited by media type.

IPX MLS Configuration Task ListTo configure one or more routers for IPX MLS, perform the tasks described in the following sections. The number of tasks you perform depends on your particular configuration.

• Adding an IPX MLS Interface to a VTP Domain (Optional)

• Enabling Multilayer Switching Protocol (MLSP) on the Router (Required)

• Assigning a VLAN ID to a Router Interface (Optional)

• Enabling IPX MLS on a Router Interface (Required)

• Specifying a Router Interface As a Management Interface (Required)

For examples of IPX MLS configurations, see the “IPX MLS Configuration Examples” section later in this document.



Adding an IPX MLS Interface to a VTP Domain

Caution Perform this configuration task only if the switch connected to your router interfaces is in a VTP domain. Perform the task before you enter any other IPX MLS interface command—specifically the mls rp ipx or mls rp management-interface command. If you enter these commands before adding the interface to a VTP domain, the interface will be automatically placed in a null domain. To place the IPX MLS interface into a domain other than the null domain, clear the IPX MLS interface configuration before you add the interface to another VTP domain. Refer to the section “Configuration, Verification, and Troubleshooting Tips” and the Catalyst 5000 Software Configuration Guide, Release 5.1.

Determine which router interfaces you will use as IPX MLS interfaces and add them to the same VTP domain as the switches.

To view the VTP configuration and its domain name on the switch, enter the show mls rp vtp-domain EXEC command at the switch Console> prompt.

To assign an MLS interface to a specific VTP domain on the MLS-RP, use the following command in interface configuration mode:

Enabling Multilayer Switching Protocol (MLSP) on the RouterTo enable MLSP on the router, use the following command in global configuration mode:

Assigning a VLAN ID to a Router Interface

Note This task is not required for RSM VLAN interfaces (virtual interfaces), ISL-encapsulated interfaces, or IEEE 802.1Q-encapsulated interfaces.

Command PurposeRouter(config-if)# mls rp vtp-domain domain-name Adds an IPX MLS interface to a VTP domain.

Command PurposeRouter(config)# mls rp ipx Globally enables MLSP on the router. MLSP is the

protocol that runs between the MLS-SE and MLS-RP.



To assign a VLAN ID to an IPX MLS interface, use the following command in interface configuration mode:

Enabling IPX MLS on a Router InterfaceTo enable IPX MLS on a router interface, use the following command in interface configuration mode:

Specifying a Router Interface As a Management InterfaceTo specify an interface as the management interface, use the following command in interface configuration mode:

Verifying IPX MLS on the RouterTo verify that you have correctly installed IPX MLS on the router, perform the following steps:

Step 1 Enter the show mls rp ipx EXEC command.

Step 2 Examine the output to learn if the VLANs are enabled.

Step 3 Examine the output to learn if the switches are listed by MAC address, indicating they are recognized by the MLS-RP.

Command Purpose

Router(config-if)# mls rp vlan-id vlan-id-number Assigns a VLAN ID to an IPX MLS interface. The assigned IPX MLS interface must be either an Ethernet or Fast Ethernet interface with no subinterfaces.

Command Purpose

Router(config-if)# mls rp ipx Enables a router interface for IPX MLS.

Command Purpose

Router(config-if)# mls rp management-interface Specifies an interface as the management interface. MLSP packets are sent and received through the management interface. Select only one IPX MLS interface connected to the switch.

Configuring IPX Multilayer SwitchingTroubleshooting Tips


Troubleshooting TipsIf you entered either the mls rp ipx interface command or the mls rp management-interface interface command on the interface before assigning it to a VTP domain, the interface will be in the null domain, instead of the VTP domain.

To remove the interface from the null domain and add it to a new VTP domain, use the following commands in interface configuration mode:

Monitoring and Maintaining IPX MLS on the RouterTo monitor and maintain IPX MLS on the router, use the following command in EXEC mode, as needed:

IPX MLS Configuration ExamplesThis section provides a complex IPX MLS network example: the Cisco 7505 switch over ISL. The example includes router and switch configurations, even though switch commands are not documented in this router publication. The section also includes sample configurations with no access lists and with standard access lists. Refer to the Catalyst 5000 Command Reference, Release 5.1 for more information.

Command Purpose

Step 1 Router(config-if)# no mls rp ipxRouter(config-if)# no mls rp management-interfaceRouter(config-if)# no mls rp vtp-domain domain-name

Removes an interface from the null domain.

Step 2 Router(config-if)# mls rp vtp-domain domain-name Adds the interface to a new VTP domain.

Command Purpose

Router# mls rp locate ipx Displays information about all switches currently shortcutting for the specified IPX flow(s).

Router# show mls rp interface type number Displays MLS details for a specific interface.

Router# show mls rp ipx Displays details for all IPX MLS interfaces on the router:

• MLS status (enabled or disabled) for switch interfaces and subinterfaces.

• Flow mask required when creating Layer 3 switching entries for the router.

• Current settings for the keepalive timer, retry timer, and retry count.

• MLSP-ID used in MLSP messages.

• List of interfaces in all VTP domains enabled for MLS.

Router# show mls rp vtp-domain domain-name Displays details about IPX MLS interfaces for a specific VTP domain.

Configuring IPX Multilayer SwitchingIPX MLS Configuration Examples


Complex IPX MLS Network ExamplesThis example consists of the following sections:

• IPX MLS Network Topology Example

• Operation Before IPX MLS Example

• Operation After IPX MLS Example

• Switch A Configuration

• Switch B Configuration

• Switch C Configuration

• MLS-RP Configuration

• Router with No Access Lists Configuration

• Configuring a Router with a Standard Access List Example

IPX MLS Network Topology Example

Figure 71 shows an IPX MLS network topology consisting of three Catalyst 5000 series switches and a Cisco 7505 router—all interconnected with ISL trunk links.

Figure 71 Example Network: IPX MLS with Cisco 7505 over ISL

ISLTrunk link

ISLTrunk link

ISLTrunk link

1/13/1

3/1 3/1

4/11/1

1/11/2 1/3

Catalyst 5505(Switch B)

Catalyst 5505(Switch C)

Catalyst 5509with NFFC

(Switch A, MLS-SE)

Cisco 7505(MLS-RP)

fa2/0

Subinterfaces:fa2/0.1 IPX network 1fa2/0.10 IPX network 10fa2/0.20 IPX network 20fa2/0.30 IPX network 30

Novell clientNC2

Novell serverNS2

Novell serverNS1

VLAN 30IPX network 30


Novell clientNC1


2326

1




• There are four VLANs (IPX networks):

– VLAN 1 (management VLAN), IPX network 1

– VLAN 10, IPX network 10



• The MLS-RP is a Cisco 7505 router with a Fast Ethernet interface (interface fastethernet2/0)

• The subinterfaces on the router interface have the following IPX network addresses:

– fastethernet2/0.1–IPX network 1




• Switch A, the MLS-SE VTP server, is a Catalyst 5509 switch with Supervisor Engine III and the NFFC II.

• Switch B and Switch C are VTP client Catalyst 5505 switches.

Operation Before IPX MLS Example

Before IPX MLS is implemented, when the source host NC1 (on VLAN 10) sends traffic destined for destination server NS2 (on VLAN 30), Switch B forwards the traffic (based on the Layer 2 forwarding table) to Switch A over the ISL trunk link. Switch A forwards the packet to the router over the ISL trunk link.

The router receives the packet on the VLAN 10 subinterface, checks the destination IPX address, and routes the packet to the VLAN 30 subinterface. Switch A receives the routed packet and forwards it to Switch C. Switch C receives the packet and forwards it to destination server NS2. This process is repeated for each packet in the flow between source host NC1 and destination server NS2.

Operation After IPX MLS Example

After IPX MLS is implemented, when the source host NC1 (on VLAN 10) sends traffic destined for destination server NS2 (on VLAN 30), Switch B forwards the traffic (based on the Layer 2 forwarding table) to Switch A (the MLS-SE) over the ISL trunk link. When the first packet enters Switch A, a candidate flow entry is established in the MLS cache. Switch A forwards the packet to the MLS-RP over the ISL trunk link.

The MLS-RP receives the packet on the VLAN 10 subinterface, checks the destination IPX address, and routes the packet to the VLAN 30 subinterface. Switch A receives the routed packet (the enabler packet) and completes the flow entry in the MLS cache for the destination IPX address of NS2. Switch A forwards the packet to Switch C, where it is forwarded to destination server NS2.

Subsequent packets destined for the IPX address of NS2 are multilayer switched by the MLS-SE based on the flow entry in the MLS cache. For example, subsequent packets in the flow from source host NC1 are forwarded by Switch B to Switch A (the MLS-SE). The MLS-SE determines that the packets are part of the established flow, rewrites the packet headers, and switches the packets directly to Switch C, bypassing the router.



Switch A Configuration

This example shows how to configure Switch A (MLS-SE):

SwitchA> (enable) set vtp domain Corporate mode serverVTP domain Corporate modifiedSwitchA> (enable) set vlan 10Vlan 10 configuration successfulSwitchA> (enable) set vlan 20Vlan 20 configuration successfulSwitchA> (enable) set vlan 30Vlan 30 configuration successfulSwitchA> (enable) set port name 1/1 Router LinkPort 1/1 name set.SwitchA> (enable) set trunk 1/1 on islPort(s) 1/1 trunk mode set to on.Port(s) 1/1 trunk type set to isl.SwitchA> (enable) set port name 1/2 SwitchB LinkPort 1/2 name set.SwitchA> (enable) set trunk 1/2 desirable islPort(s) 1/2 trunk mode set to desirable.Port(s) 1/2 trunk type set to isl.SwitchA> (enable) set port name 1/3 SwitchC LinkPort 1/3 name set.SwitchA> (enable) set trunk 1/3 desirable islPort(s) 1/3 trunk mode set to desirable.Port(s) 1/3 trunk type set to isl.SwitchA> (enable) set mls enable ipxIPX Multilayer switching is enabled.SwitchA> (enable) set mls include ipx 10.1.1.1IPX Multilayer switching enabled for router 10.1.1.1.SwitchA> (enable) set port name 3/1 Destination D2Port 3/1 name set.SwitchA> (enable) set vlan 20 3/1VLAN 20 modified.VLAN 1 modified.VLAN Mod/Ports---- -----------------------20 3/1 SwitchA> (enable)

Switch B Configuration

This example shows how to configure Switch B:

SwitchB> (enable) set port name 1/1 SwitchA LinkPort 1/1 name set.SwitchB> (enable) set port name 3/1 Source S1Port 3/1 name set.SwitchB> (enable) set vlan 10 3/1VLAN 10 modified.VLAN 1 modified.VLAN Mod/Ports---- -----------------------10 3/1 SwitchB> (enable)



Switch C Configuration

This example shows how to configure Switch C:

SwitchC> (enable) set port name 1/1 SwitchA LinkPort 1/1 name set.SwitchC> (enable) set port name 3/1 Destination D1Port 3/1 name set.SwitchC> (enable) set vlan 30 3/1VLAN 30 modified.VLAN 1 modified.VLAN Mod/Ports---- -----------------------30 3/1 SwitchC> (enable) set port name 4/1 Source S2Port 4/1 name set.SwitchC> (enable) set vlan 30 4/1VLAN 30 modified.VLAN 1 modified.VLAN Mod/Ports---- -----------------------30 3/1 4/1 SwitchC> (enable)

MLS-RP Configuration

This example shows how to configure the MLS-RP:

mls rp ipxinterface fastethernet 2/0full-duplexmls rp vtp-domain Engineering

interface fastethernet2/0.1encapsulation isl 1ipx address 10.1.1.1 255.255.255.0mls rp ipxmls rp management-interface

interface fastethernet2/0.10encapsulation isl 10ipx network 10mls rp ipx





Router with No Access Lists Configuration

This example shows how to configure the RSM VLAN interfaces with no access lists. Therefore, the flow mask mode is destination.

Building configuration...

Current configuration:!version 12.0

.

.

.ipx routing 0010.0738.2917mls rp ip mls rp ipx

.

.

.interface Vlan21 ip address 10.5.5.155 255.255.255.0 ipx network 2121 mls rp vtp-domain Engineering mls rp management-interface mls rp ip mls rp ipx!interface Vlan22ip address 10.2.2.155 255.255.255.0 ipx network 2222 mls rp vtp-domain Engineering mls rp ip mls rp ipx!...end

Configuring a Router with a Standard Access List Example

This example shows how to configure a standard access list on the RSM VLAN 3 interface. Therefore, the flow mask mode is destination-source.

Router# show runBuilding configuration...Current configuration:!version 12.0!interface Vlan22ip address 10.2.2.155 255.255.255.0 ipx access-group 800 out ipx network 2222 mls rp vtp-domain Engineering mls rp ip mls rp ipx!

.



.

.!!!

access-list 800 deny 1111 2222access-list 800 permit FFFFFFFF FFFFFFFF

.

.

.end

Multicast Distributed Switching


Configuring Multicast Distributed Switching

This chapter describes the required and optional tasks for configuring Multicast Distributed Switching (MDS).



Prior to multicast distributed switching, IP multicast traffic was always switched at the Route Processor (RP) in the Route Switch Processor (RSP)-based platforms. Starting with Cisco IOS Release 11.2 GS, IP multicast traffic can be distributed switched on RSP-based platforms with VIPs. Furthermore, MDS is the only multicast switching method on the Cisco 12000 Gigabit Switch Router (GSR), starting with Cisco IOS Release 11.2(11)GS.

Switching multicast traffic at the RP had the following disadvantages:

• The load on the RP increased. This affected important route updates and calculations (for BGP, among others) and could stall the router if the multicast load was substantial.

• The net multicast performance was limited to what a single RP could switch.

MDS solves these problems by performing distributed switching of multicast packets received at the line cards (VIPs in the case of RSP, and line cards in the case of GSR). The line card is the interface card that houses the VIPs (in the case of RSP) and the GSR line card (in the case of GSR). MDS is accomplished using a forwarding data structure called a Multicast Forwarding Information Base (MFIB), which is a subset of the routing table. A copy of MFIB runs on each line card and is always kept up to date with the MFIB table of the RP.

In the case of RSP, packets received on non-VIP IPs are switched by the RP.

MDS can work in conjunction with Cisco Express Forwarding (CEF), unicast distributed fast switching (DFS), or flow switching.

Configuring Multicast Distributed SwitchingMDS Configuration Task List


MDS Configuration Task ListTo configure MDS, perform the task described in the following sections. The first section contains a required task; the remaining task is optional:

• Enabling MDS (Required)

• Monitoring and Maintaining MDS (Optional)

Enabling MDSTo enable MDS, you must enable it globally and on at least one interface because MDS is an attribute of the interface. Use the following commands beginning in global configuration mode:

Note When you enable an interface to perform distributed switching of incoming multicast packets, you are configuring the physical interface, not the logical interface (subinterface). All subinterfaces are included in the physical interface.

Monitoring and Maintaining MDSTo maintain MDS on the line cards, use the following command in EXEC mode:

To maintain MDS on the RP, use the following commands in EXEC mode, as needed:

Command Purpose

Step 1 Router(config)# ip multicast-routing distributed

Enables MDS globally.

Step 2 Router(config)# interface type number Configures an interface.

Step 3 Router(config-if)# ip route-cache distributed Enables distributed switching on the RSP. (This step is required on the RSP platform only.)

Step 4 Router(config-if)# ip mroute-cache distributed Enables MDS on the interface.

Repeat Steps 2 through 4 for each interface that you want to perform MDS.

Command PurposeRouter# clear ip mds forwarding Clears the MFIB table of the line card and resynchronizes

with the RP.

Command Purpose

Router# clear ip mroute {* | group [source]} Clears multicast routes and counts.

Router# clear ip pim interface count Clears all packet counts on the line cards.

Configuring Multicast Distributed SwitchingMDS Configuration Example


To monitor MDS on the line cards, use the following commands in EXEC mode, as needed. Remember that to reach a line card’s console, enter the attach slot# command, using the slot number where the line card resides.

To monitor MDS on the RP, use the following commands in EXEC mode, as needed:

MDS Configuration ExampleThe following example enables MDS. The ip route-cache distributed interface configuration command is needed on the RSP only, not on the GSR.

ip multicast-routing distributedinterface pos 1/0/0ip route-cache distributedip mroute-cache distributed

Command Purpose

Router# show ip mds forwarding [group-address] [source-address]

Displays the MFIB table, forwarding information, related flags, and counts.

Router# show ip mds summary Displays a summary of the MFIB.

Command PurposeRouter# show ip mds stats [switching | linecard] Displays switching statistics or line card statistics for MDS.

Router# show ip mds interface Displays the status of MDS interfaces.

Router# show ip pim interface [type number] count Displays switching counts for unicast distributed fast switching and other fast switching statistics.

Router# show ip mcache [group [source]] Displays the contents of the IP fast-switching cache.

Router# show interface stats Displays numbers of packets that were process switched, fast switched, and distributed switched.

VLANs


Routing Between VLANs Overview

This chapter provides an overview of VLANs. It describes the encapsulation protocols used for routing between VLANs and provides some basic information about designing VLANs.

This chapter describes VLANs. It contains the following sections:

• What Is a VLAN?

• VLAN Colors

• Why Implement VLANs?

• Communicating Between VLANs

• VLAN Interoperability

• Designing Switched VLANs

What Is a VLAN?A VLAN is a switched network that is logically segmented on an organizational basis, by functions, project teams, or applications rather than on a physical or geographical basis. For example, all workstations and servers used by a particular workgroup team can be connected to the same VLAN, regardless of their physical connections to the network or the fact that they might be intermingled with other teams. Reconfiguration of the network can be done through software rather than by physically unplugging and moving devices or wires.

A VLAN can be thought of as a broadcast domain that exists within a defined set of switches. A VLAN consists of a number of end systems, either hosts or network equipment (such as bridges and routers), connected by a single bridging domain. The bridging domain is supported on various pieces of network equipment; for example, LAN switches that operate bridging protocols between them with a separate bridge group for each VLAN.

VLANs are created to provide the segmentation services traditionally provided by routers in LAN configurations. VLANs address scalability, security, and network management. Routers in VLAN topologies provide broadcast filtering, security, address summarization, and traffic flow management. None of the switches within the defined group will bridge any frames, not even broadcast frames, between two VLANs. Several key issues described in the following sections need to be considered when designing and building switched LAN internetworks:

• LAN Segmentation

• Security

• Broadcast Control

Routing Between VLANs OverviewWhat Is a VLAN?


• Performance

• Network Management

• Communication Between VLANs

LAN SegmentationVLANs allow logical network topologies to overlay the physical switched infrastructure such that any arbitrary collection of LAN ports can be combined into an autonomous user group or community of interest. The technology logically segments the network into separate Layer 2 broadcast domains whereby packets are switched between ports designated to be within the same VLAN. By containing traffic originating on a particular LAN only to other LANs in the same VLAN, switched virtual networks avoid wasting bandwidth, a drawback inherent to traditional bridged and switched networks in which packets are often forwarded to LANs with no need for them. Implementation of VLANs also improves scalability, particularly in LAN environments that support broadcast- or multicast-intensive protocols and applications that flood packets throughout the network.

Figure 72 illustrates the difference between traditional physical LAN segmentation and logical VLAN segmentation.

Figure 72 LAN Segmentation and VLAN Segmentation

CatalystVLAN switch

VLAN 1

VLAN segmentationTraditional LAN segmentation

VLAN 2 VLAN 3

LAN 1

Shared hub

Shared hub

Shared hub

Floor 3

Floor 2

Floor 1

LAN 2

LAN 3S

6619

CatalystVLAN switch

CatalystVLAN switch

Router



SecurityVLANs improve security by isolating groups. High-security users can be grouped into a VLAN, possibly on the same physical segment, and no users outside that VLAN can communicate with them.

Broadcast ControlJust as switches isolate collision domains for attached hosts and only forward appropriate traffic out a particular port, VLANs provide complete isolation between VLANs. A VLAN is a bridging domain, and all broadcast and multicast traffic is contained within it.

PerformanceThe logical grouping of users allows an accounting group to make intensive use of a networked accounting system assigned to a VLAN that contains just that accounting group and its servers. That group’s work will not affect other users. The VLAN configuration improves general network performance by not slowing down other users sharing the network.

Network ManagementThe logical grouping of users allows easier network management. It is not necessary to pull cables to move a user from one network to another. Adds, moves, and changes are achieved by configuring a port into the appropriate VLAN.

Network Monitoring Using SNMP

SNMP support has been added to provide mib-2 interfaces sparse table support for Fast Ethernet subinterfaces. Monitor your VLAN subinterface using the show vlans EXEC command. For more information on configuring SNMP on your Cisco network device or enabling an SNMP agent for remote access, refer to the “Configuring SNMP” chapter in the Cisco IOS Configuration Fundamentals Configuration Guide.

Communication Between VLANsCommunication between VLANs is accomplished through routing, and the traditional security and filtering functions of the router can be used. Cisco IOS software provides network services such as security filtering, quality of service (QoS), and accounting on a per-VLAN basis. As switched networks evolve to distributed VLANs, Cisco IOS software provides key inter-VLAN communications and allows the network to scale.

Before Cisco IOS Release 12.2, Cisco IOS support for interfaces that have 802.1Q encapsulation configured is IP, IP multicast, and IPX routing between respective VLANs represented as subinterfaces on a link. New functionality has been added in IEEE 802.1Q support for bridging on those interfaces and the capability to configure and use integrated routing and bridging (IRB).

The following section describes how bridging communication between IEEE 802.1Q VLANs occurs:

• Relaying Function



• Native VLAN

• PVST+

• Integrated Routing and Bridging

Relaying Function

The relaying function level, as displayed in Figure 73, is the lowest level in the architectural model described in the IEEE 802.1Q standard and presents three types of rules:

• Ingress rules—Rules relevant to the classification of received frames belonging to a VLAN.

• Forwarding rules between ports—Decides to filter or forward the frame.

• Egress rules (output of frames from the switch)—Decides if the frame must be sent tagged or untagged.

Figure 73 Relaying Function

The Tagging Scheme

Figure 74 shows the tagging scheme proposed by the 802.3ac standard, that is, the addition of the four octets after the source MAC address. Their presence is indicated by a particular value of the EtherType field (called TPID), which has been fixed to be equal to 0x8100. When a frame has the EtherType equal to 0x8100, this frame carries the tag IEEE 802.1Q/802.1p. The tag is stored in the following two octets and it contains 3 bits of user priority, 1 bit of Canonical Format Identifier (CFI), and 12 bits of VLAN ID (VID). The 3 bits of user priority are used by the 802.1p standard; the CFI is used for compatibility

5471

3

Port stateinformation

Ingressrules

Forwardingprocess

Filteringdatabase

Port stateinformation

Egressrules

Framereception

Frametransmission



reasons between Ethernet-type networks and Token Ring-type networks. The VID is the identification of the VLAN, which is basically used by the 802.1Q standard; being on 12 bits, it allows the identification of 4096 VLANs.

After the two octets of TPID and the two octets of the Tag Control Information field there are two octets that originally would have been located after the Source Address field where there is the TPID. They contain either the MAC length in the case of IEEE 802.3 or the EtherType in the case of Ethernet version 2.

Figure 74 Tagging Scheme

The EtherType and VLAN ID are inserted after the MAC source address, but before the original Ethertype/Length or Logical Link Control (LLC). The 1-bit CFI included a T-R Encapsulation bit so that Token Ring frames can be carried across Ethernet backbones without using 802.1H translation.

Adding a Tag Recomputes the Frame Control Sequence

Figure 75 shows how adding a tag in a frame recomputes the Frame Control Sequence. 802.1p and 802.1Q share the same tag.

Figure 75 Adding a Tag Recomputes the Frame Control Sequence

5471

2

Destination address

Source address

EtherType = 0x8100

Tag control information

MAC length/type

Data

VID (VLAN ID) - 12 bits

Userpriority CFI

PAD

FCS

6

6

2

2

2

Variable

4

5471

1

Dest FCSSrc Len/Etype Data

Dest

PRI VLAN ID

Token ring encapsulation flag

Taggedframe

Originalframe

(VLAN ID and TR encapsulationsare 802.1Q,not 802.1p)

Src Etype Len/EtypeTag FCSData



Native VLAN

Each physical port has a parameter called PVID. Every 802.1Q port is assigned a PVID value that is of its native VLAN ID (default is VLAN 1). All untagged frames are assigned to the LAN specified in the PVID parameter. When a tagged frame is received by a port, the tag is respected. If the frame is untagged, the value contained in the PVID is considered as a tag. Because the frame is untagged and the PVID is tagged to allow the coexistence, as shown in Figure 76, on the same pieces of cable of VLAN-aware bridge/stations and of VLAN-unaware bridges/stations. Consider, for example, the two stations connected to the central trunk link in the lower part of Figure 76. They are VLAN-unaware and they will be associated to the VLAN C, because the PVIDs of the VLAN-aware bridges are equal to VLAN C. Because the VLAN-unaware stations will send only untagged frames, when the VLAN-aware bridge devices receive these untagged frames they will assign them to VLAN C.

Figure 76 Native VLAN

PVST+

PVST+ provides support for 802.1Q trunks and the mapping of multiple spanning trees to the single spanning tree of 802.1Q switches.

The PVST+ architecture distinguishes three types of regions:

• A PVST region

• A PVST+ region

• A MST region

Each region consists of a homogenous type of switch. A PVST region can be connected to a PVST+ region by connecting two ISL ports. Similarly, a PVST+ region can be connected to an MST region by connecting two 802.1Q ports.

PVID = C PVID = C

PVID = C

PVID = C

VLAN-unawareend station

Trunklink

PVID = A

VLAN A

VLAN-awarebridge

VLAN-awarebridge

VLAN B

VLAN A

VLAN B

VLAN C

5471

0

Accessports

Accessports

PVID = B

PVID = A

PVID = B

VLAN-awareend station



VLAN BVLAN C



At the boundary between a PVST region and a PVST+ region the mapping of spanning trees is one-to-one. At the boundary between a MST region and a PVST+ region, the ST in the MST region maps to one PVST in the PVST+ region. The one it maps to is called the common spanning tree (CST). The default CST is the PVST of VLAN 1 (Native VLAN).

All PVSTs, except for the CST, are tunneled through the MST region. Tunneling means that bridge protocol data units (BPDUs) are flooded through the MST region along the single spanning tree present in the MST region.

Note When a Dot1q VLAN is configured on an interface, a default VLAN 1 is automatically created to process the CST. The default VLAN 1 created is only used for processing spanning tree BPDU packets. Even though these packets are Dot1q untagged, no other untagged data packet will be processed by this VLAN 1. Instead, all of the untagged data packet will be processed by the explicitly defined Native VLAN. If, however, no Native VLAN is defined, VLAN 1 will become the default the Native VLAN 1 (it can also be explicitly defined as Native VLAN 1) to handle all the untagged packets, including CST BPDUs and data packets.

Ingress and Egress Rules

The BPDU transmission on the 802.1Q port of a PVST+ router will be implemented in compliance with the following rules:

• The CST BPDU (of VLAN 1, by default) is sent to the IEEE address.

• All the other BPDUs are sent to Shared Spanning Tree Protocol (SSTP)-Address and encapsulated with Logical Link Control-Subnetwork Access Protocol (LLC-SNAP) header.

• The BPDU of the CST and BPDU of the VLAN equal to the PVID of the 802.1Q trunk are sent untagged.

• All other BPDUs are sent tagged with the VLAN ID.

• The CST BPDU is also sent to the SSTP address.

• Each SSTP-addressed BPDU is also tailed by a Tag-Length-Value for the PVID checking.

The BPDU reception on the 802.1Q port of a PVST+ router will follow these rules:

• All untagged IEEE addressed BPDUs must be received on the PVID of the 802.1Q port.

• The IEEE addressed BPDUs whose VLAN ID matches the Native VLAN are processed by CST.

• All the other IEEE addressed BPDUs whose VLAN ID does not match the Native VLAN and whose port type is not of 802.1Q are processed by the spanning tree of that particular VLAN ID.

• The SSTP addressed BPDU whose VLAN ID is not equal to the TLV are dropped and the ports are blocked for inconsistency.

• All the other SSTP addressed BPDUs whose VLAN ID is not equal to the Native VLAN are processed by the spanning tree of that particular VLAN ID.

• The SSTP addressed BPDUs whose VLAN ID is equal to the Native VLAN are dropped. It is used for consistency checking.

Integrated Routing and Bridging

IRB enables a user to route a given protocol between routed interfaces and bridge groups or route a given protocol between the bridge groups. Integrated routing and bridging is supported on the following protocols:

Routing Between VLANs OverviewVLAN Colors


• IP

• IPX

• AppleTalk

VLAN ColorsVLAN switching is accomplished through frame tagging where traffic originating and contained within a particular virtual topology carries a unique VLAN ID as it traverses a common backbone or trunk link. The VLAN ID enables VLAN switching devices to make intelligent forwarding decisions based on the embedded VLAN ID. Each VLAN is differentiated by a color, or VLAN identifier. The unique VLAN ID determines the frame coloring for the VLAN. Packets originating and contained within a particular VLAN carry the identifier that uniquely defines that VLAN (by the VLAN ID).

The VLAN ID allows VLAN switches and routers to selectively forward packets to ports with the same VLAN ID. The switch that receives the frame from the source station inserts the VLAN ID and the packet is switched onto the shared backbone network. When the frame exits the switched LAN, a switch strips the header and forwards the frame to interfaces that match the VLAN color. If you are using a Cisco network management product such as VlanDirector, you can actually color code the VLANs and monitor VLAN graphically.

Why Implement VLANs?Network managers can logically group networks that span all major topologies, including high-speed technologies such as, ATM, FDDI, and Fast Ethernet. By creating virtual LANs, system and network administrators can control traffic patterns and react quickly to relocations and keep up with constant changes in the network due to moving requirements and node relocation just by changing the VLAN member list in the router configuration. They can add, remove, or move devices or make other changes to network configuration using software to make the changes.

Issues regarding benefits of creating VLANs should have been addressed when you developed your network design. Issues to consider include the following:

• Scalability

• Performance improvements

• Security

• Network additions, moves, and changes

Communicating Between VLANsCisco IOS software provides full-feature routing at Layer 3 and translation at Layer 2 between VLANs. Five different protocols are available for routing between VLANs:

• Inter-Switch Link Protocol

• IEEE 802.10 Protocol

• IEEE 802.1Q Protocol

• ATM LANE Protocol

• ATM LANE Fast Simple Server Replication Protocol

Routing Between VLANs OverviewCommunicating Between VLANs


All five of these technologies are based on OSI Layer 2 bridge multiplexing mechanisms.

Inter-Switch Link ProtocolThe Inter-Switch Link (ISL) protocol is used to interconnect two VLAN-capable Ethernet, Fast Ethernet, or Gigabit Ethernet devices, such as the Catalyst 3000 or 5000 switches and Cisco 7500 routers. The ISL protocol is a packet-tagging protocol that contains a standard Ethernet frame and the VLAN information associated with that frame. The packets on the ISL link contain a standard Ethernet, FDDI, or Token Ring frame and the VLAN information associated with that frame. ISL is currently supported only over Fast Ethernet links, but a single ISL link, or trunk, can carry different protocols from multiple VLANs.

Procedures for configuring ISL and Token Ring ISL (TRISL) features are provided in the “Configuring Routing Between VLANs with Inter-Switch Link Encapsulation” chapter later in this publication.

IEEE 802.10 ProtocolThe IEEE 802.10 protocol provides connectivity between VLANs. Originally developed to address the growing need for security within shared LAN/MAN environments, it incorporates authentication and encryption techniques to ensure data confidentiality and integrity throughout the network. Additionally, by functioning at Layer 2, it is well suited to high-throughput, low-latency switching environments. The IEEE 802.10 protocol can run over any LAN or HDLC serial interface.

Procedures for configuring routing between VLANs with IEEE 802.10 encapsulation are provided in the “Configuring Routing Between VLANs with IEEE 802.10 Encapsulation” chapter later in this publication.

IEEE 802.1Q ProtocolThe IEEE 802.1Q protocol is used to interconnect multiple switches and routers, and for defining VLAN topologies. Cisco currently supports IEEE 802.1Q for Fast Ethernet and Gigabit Ethernet interfaces.

Note Cisco does not support IEEE 802.1Q encapsulation for Ethernet interfaces.

Procedures for configuring routing between VLANs with IEEE 802.1Q encapsulation are provided in the “Configuring Routing Between VLANs with IEEE 802.1Q Encapsulation” chapter later in this publication.

ATM LANE ProtocolThe ATM LAN Emulation (LANE) protocol provides a way for legacy LAN users to take advantage of ATM benefits without requiring modifications to end-station hardware or software. LANE emulates a broadcast environment like IEEE 802.3 Ethernet on top of an ATM network that is a point-to-point environment.

LANE makes ATM function like a LAN. LANE allows standard LAN drivers like NDIS and ODI to be used. The virtual LAN is transparent to applications. Applications can use normal LAN functions without the underlying complexities of the ATM implementation. For example, a station can send broadcasts and multicasts, even though ATM is defined as a point-to-point technology and does not support any-to-any services.

Routing Between VLANs OverviewVLAN Interoperability


To accomplish this, special low-level software is implemented on an ATM client workstation, called the LAN Emulation Client (LEC). The client software communicates with a central control point called a LAN Emulation Server (LES). A broadcast and unknown server (BUS) acts as a central point to distribute broadcasts and multicasts. The LAN Emulation Configuration Server (LECS) holds a database of LECs and the ELANs they belong to. The database is maintained by a network administrator.

These protocols are described in detail in the Cisco Internetworking Design Guide.

ATM LANE Fast Simple Server Replication ProtocolTo improve the ATM LANE Simple Server Replication Protocol (SSRP), Cisco introduced the ATM LANE Fast Simple Server Replication Protocol (FSSRP). FSSRP differs from LANE SSRP in that all configured LANE servers of an ELAN are always active. FSSRP-enabled LANE clients have virtual circuits (VCs) established to a maximum of four LANE servers and BUSs at one time. If a single LANE server goes down, the LANE client quickly switches over to the next LANE server and BUS, resulting in no data or LE ARP table entry loss and no extraneous signalling.

The FSSRP feature improves upon SSRP such that LANE server and BUS switchover for LANE clients is immediate. With SSRP, a LANE server would go down, and depending on the network load, it may have taken considerable time for the LANE client to come back up joined to the correct LANE server and BUS. In addition to going down with SSRP, the LANE client would do the following:

• Clear out its data direct VCs

• Clear out its LE ARP entries

• Cause substantial signalling activity and data loss

FSSRP was designed to alleviate these problems with the LANE client. With FSSRP, each LANE client is simultaneously joined to up to four LANE servers and BUSs. The concept of the master LANE server and BUS is maintained; the LANE client uses the master LANE server when it needs LANE server BUS services. However, the difference between SSRP and FSSRP is that if and when the master LANE server goes down, the LANE client is already connected to multiple backup LANE servers and BUSs. The LANE client simply uses the next backup LANE server and BUS as the master LANE server and BUS.

VLAN InteroperabilityCisco IOS features bring added benefits to the VLAN technology. Enhancements to ISL, IEEE 802.10, and ATM LANE implementations enable routing of all major protocols between VLANs. These enhancements allow users to create more robust networks incorporating VLAN configurations by providing communications capabilities between VLANs.

Inter-VLAN CommunicationsThe Cisco IOS supports full routing of several protocols over ISL and ATM LANE VLANs. IP, Novell IPX, and AppleTalk routing are supported over IEEE 802.10 VLANs. Standard routing attributes such as network advertisements, secondaries, and help addresses are applicable, and VLAN routing is fast switched. Table 42 shows protocols supported for each VLAN encapsulation format and corresponding Cisco IOS software releases.

Routing Between VLANs OverviewDesigning Switched VLANs


VLAN TranslationVLAN translation refers to the ability of the Cisco IOS software to translate between different VLANs or between VLAN and non-VLAN encapsulating interfaces at Layer 2. Translation is typically used for selective inter-VLAN switching of nonroutable protocols and to extend a single VLAN topology across hybrid switching environments. It is also possible to bridge VLANs on the main interface; the VLAN encapsulating header is preserved. Topology changes in one VLAN domain do not affect a different VLAN.

Designing Switched VLANsBy the time you are ready to configure routing between VLANs, you will have already defined them through the switches in your network. Issues related to network design and VLAN definition should be addressed during your network design. Refer to the Cisco Internetworking Design Guide and appropriate switch documentation for information on these topics:

• Sharing resources between VLANs

• Load balancing

• Redundant links

• Addressing

• Segmenting networks with VLANs—Segmenting the network into broadcast groups improves network security. Use router access lists based on station addresses, application types, and protocol types.

• Routers and their role in switched networks—In switched networks, routers perform broadcast management, route processing, and distribution, and provide communication between VLANs. Routers provide VLAN access to shared resources and connect to other parts of the network that are either logically segmented with the more traditional subnet approach or require access to remote sites across wide-area links.

Table 42 Inter-VLAN Routing Protocol Support

Protocol ISL ATM LANE IEEE 802.10

IP Release 11.1 Release 10.3 Release 11.1

Novell IPX (default encapsulation)

Release 11.1 Release 10.3 Release 11.1

Novell IPX (configurable encapsulation)

Release 11.3 Release 10.3 Release 11.3

AppleTalk Phase II Release 11.3 Release 10.3 —

DECnet Release 11.3 Release 11.0 —

Banyan VINES Release 11.3 Release 11.2 —

XNS Release 11.3 Release 11.2 —

CLNS Release 12.1 — —

IS-IS Release 12.1 — —


Configuring Routing Between VLANs with Inter-Switch Link Encapsulation

This chapter describes the Inter-Switch Link (ISL) protocol and provides guidelines for configuring ISL and Token Ring ISL (TRISL) features.



Overview of the ISL ProtocolISL is a Cisco protocol for interconnecting multiple switches and maintaining VLAN information as traffic goes between switches. ISL provides VLAN capabilities while maintaining full wire speed performance on Fast Ethernet links in full- or half-duplex mode. ISL operates in a point-to-point environment and will support up to 1000 VLANs. You can define virtually as many logical networks as are necessary for your environment.

This chapter describes how to configure routing between VLANs using ISL encapsulation.

Frame Tagging in ISLWith ISL, an Ethernet frame is encapsulated with a header that transports VLAN IDs between switches and routers. A 26-byte header that contains a 10-bit VLAN ID is prepended to the Ethernet frame.

A VLAN ID is added to the frame only when the frame is destined for a nonlocal network. Figure 77 shows VLAN packets traversing the shared backbone. Each VLAN packet carries the VLAN ID within the packet header.

Configuring Routing Between VLANs with Inter-Switch Link EncapsulationISL Encapsulation Configuration Task List


Figure 77 VLAN Packets Traversing the Shared Backbone

ISL Encapsulation Configuration Task ListYou can configure routing between any number of VLANs in your network. This section documents the configuration tasks for each protocol supported with ISL encapsulation. The basic process is the same, regardless of the protocol being routed. It involves the following tasks:

• Enabling the protocol on the router

• Enabling the protocol on the interface

• Defining the encapsulation format as ISL or TRISL

• Customizing the protocol according to the requirements for your environment

To configure routing between any number of VLANs in your network, perform the tasks described in the following sections particular to your network:

• Configuring AppleTalk Routing over ISL

• Configuring Banyan VINES Routing over ISL

• Configuring DECnet Routing over ISL

• Configuring the Hot Standby Router Protocol over ISL

• Configuring IP Routing over TRISL

• Configuring IPX Routing over TRISL

• Configuring VIP Distributed Switching over ISL

• Configuring XNS Routing over ISL

• Configuring CLNS Routing over ISL

• Configuring IS-IS Routing over ISL

• Monitoring and Maintaining VLAN Subinterfaces

Refer to the “ISL Encapsulation Configuration Examples” section at the end of this chapter for sample configurations.

Configuring AppleTalk Routing over ISLAppleTalk can be routed over VLAN subinterfaces using the ISL and IEEE 802.10 VLAN encapsulation protocols. The AppleTalk Routing over ISL and IEEE 802.10 Virtual LANs feature provides full-feature Cisco IOS software AppleTalk support on a per-VLAN basis, allowing standard AppleTalk capabilities to be configured on VLANs.

TokenRing Green

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To route AppleTalk over ISL or IEEE 802.10 between VLANs, you need to customize the subinterface to create the environment in which it will be used. Perform the tasks described in the following sections in the order in which they appear:

• Enabling AppleTalk Routing

• Defining the VLAN Encapsulation Format

• Configuring AppleTalk on the Subinterface

Enabling AppleTalk Routing

To enable AppleTalk routing on either ISL or 802.10 interfaces, use the following command in global configuration mode:

Defining the VLAN Encapsulation Format

To define the VLAN encapsulation format as either ISL or 802.10, use the following commands in interface configuration mode:

Configuring AppleTalk on the Subinterface

After you enable AppleTalk globally and define the encapsulation format, you need to enable it on the subinterface by specifying the cable range and naming the AppleTalk zone for each interface. To enable the AppleTalk protocol on the subinterface, use the following commands in interface configuration mode:

Command PurposeRouter(config)# appletalk routing [eigrp router-number]

Enables AppleTalk routing globally.

Command Purpose

Step 1 Router(config-if)# interface type slot/port.subinterface-number

Specifies the subinterface the VLAN will use.

Step 2 Router(config-if)# encapsulation isl vlan-identifier

or

Router(config-if)# encapsulation sde said

Defines the encapsulation format as either ISL (isl) or IEEE 802.10 (sde), and specifies the VLAN identifier or security association identifier, respectively.

Command Purpose

Router(config-if)# appletalk cable-range cable-range [network.node]

Assigns the AppleTalk cable range and zone for the subinterface.

Router(config-if)# appletalk zone zone-name Assigns the AppleTalk zone for the subinterface.



Configuring Banyan VINES Routing over ISLBanyan VINES can be routed over VLAN subinterfaces using the ISL encapsulation protocol. The Banyan VINES Routing over ISL Virtual LANs feature provides full-feature Cisco IOS software Banyan VINES support on a per-VLAN basis, allowing standard Banyan VINES capabilities to be configured on VLANs.

To route Banyan VINES over ISL between VLANs, you need to configure ISL encapsulation on the subinterface. Perform the tasks described in the following sections in the order in which they appear:

• Enabling Banyan VINES Routing


• Configuring Banyan VINES on the Subinterface

Enabling Banyan VINES Routing

To begin the VINES routing configuration, use the following command in global configuration mode:


To define the VINES routing encapsulation format, use the following commands in interface configuration mode:

Configuring Banyan VINES on the Subinterface

After you enable Banyan VINES globally and define the encapsulation format, you need to enable VINES on the subinterface by specifying the VINES routing metric. To enable the Banyan VINES protocol on the subinterface, use the following command in interface configuration mode:

Configuring DECnet Routing over ISLDECnet can be routed over VLAN subinterfaces using the ISL VLAN encapsulation protocols. The DECnet Routing over ISL Virtual LANs feature provides full-feature Cisco IOS software DECnet support on a per-VLAN basis, allowing standard DECnet capabilities to be configured on VLANs.

Command PurposeRouter(config)# vines routing [address] Enables Banyan VINES routing globally.

Command Purpose


Specifies the subinterface on which ISL will be used.


Defines the encapsulation format as ISL (isl), and specifies the VLAN identifier.

Command Purpose

Router(config-if)# vines metric [whole [fractional]] Enables VINES routing on an interface.



To route DECnet over ISL VLANs, you need to configure ISL encapsulation on the subinterface. Perform the tasks described in the following sections in the order in which they appear.

• Enabling DECnet Routing


• Configuring DECnet on the Subinterface

Enabling DECnet Routing

To begin the DECnet routing configuration, use the following command in global configuration mode:


To define the encapsulation format, use the following commands in interface configuration mode:

Configuring DECnet on the Subinterface

To configure DECnet routing on the subinterface, use the following command in interface configuration mode:

Configuring the Hot Standby Router Protocol over ISLThe Hot Standby Router Protocol (HSRP) provides fault tolerance and enhanced routing performance for IP networks. HSRP allows Cisco IOS routers to monitor each other’s operational status and very quickly assume packet forwarding responsibility in the event the current forwarding device in the HSRP group fails or is taken down for maintenance. The standby mechanism remains transparent to the attached hosts and can be deployed on any LAN type. With multiple Hot Standby groups, routers can simultaneously provide redundant backup and perform loadsharing across different IP subnets.

Command Purpose

Router(config)# decnet [network-number] routing [decnet-address]

Enables DECnet on the router.

Command Purpose





Command Purpose

Router(config-if)# decnet cost [cost-value] Enables DECnet routing on an interface.



Figure 78 illustrates HSRP in use with ISL providing routing between several VLANs.

Figure 78 Hot Standby Router Protocol in VLAN Configurations

A separate HSRP group is configured for each VLAN subnet so that Cisco IOS router A can be the primary and forwarding router for VLANs 10 and 20. At the same time, it acts as backup for VLANs 30 and 40. Conversely, Router B acts as the primary and forwarding router for ISL VLANs 30 and 40, as well as the secondary and backup router for distributed VLAN subnets 10 and 20.

Running HSRP over ISL allows users to configure redundancy between multiple routers that are configured as front ends for VLAN IP subnets. By configuring HSRP over ISLs, users can eliminate situations in which a single point of failure causes traffic interruptions. This feature inherently provides some improvement in overall networking resilience by providing load balancing and redundancy capabilities between subnets and VLANs.

To configure HSRP over ISLs between VLANs, you need to create the environment in which it will be used. Perform the tasks described in the following sections in the order in which they appear.

• Defining the Encapsulation Format

• Defining the IP Address

• Enabling HSRP

Cisco IOSrouter

Cisco VLANswitch

Cisco VLANswitch

ISL ISL

ISL

HSRP

VLAN 20 VLAN 10 VLAN 40

VLAN 10 VLAN 30 VLAN 20

Cisco IOSrouter

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Defining the Encapsulation Format

To define the encapsulation format as ISL, use the following commands in interface configuration mode:

Defining the IP Address

After you have specified the encapsulation format, to define the IP address over which HSRP will be routed, use the following command in interface configuration mode:

Enabling HSRP

To enable HSRP on an interface, enable the protocol, then customize it for the interface. Use the following command in interface configuration mode:

Note For more information on HSRP, see the “Configuring IP Services” chapter in the Cisco IOS IP Configuration Guide.

To customize Hot Standby group attributes, use the following commands in interface configuration mode, as needed:

Command Purpose




Defines the encapsulation format, and specifies the VLAN identifier.

Command PurposeRouter(config-if)# ip address ip-address mask [secondary] Specifies the IP address for the subnet on which ISL

will be used.

Command PurposeRouter(config-if)# standby [group-number] ip [ip-address [secondary]]

Enables HSRP.

Command PurposeRouter(config-if)# standby [group-number] timers hellotime holdtime

Configures the time between hello packets and the hold time before other routers declare the active router to be down.

Router(config-if)# standby [group-number] priority priority Sets the Hot Standby priority used to choose the active router.

Router(config-if)# standby [group-number] preempt Specifies that if the local router has priority over the current active router, the local router should attempt to take its place as the active router.



Configuring IP Routing over TRISLThe IP routing over TRISL VLANs feature extends IP routing capabilities to include support for routing IP frame types in VLAN configurations.

Enabling IP Routing

IP routing is automatically enabled in the Cisco IOS software for routers. To reenable IP routing if it has been disabled, use the following command in global configuration mode:

Once you have IP routing enabled on the router, you can customize the characteristics to suit your environment. If necessary, refer to the IP configuration chapters in the Cisco IOS IP Routing Configuration Guide for guidelines on configuring IP.


To define the encapsulation format as TRISL, use the following commands in interface configuration mode:

The DRiP database is automatically enabled when TRISL encapsulation is configured, and at least one TrBRF is defined, and the interface is configured for SRB or for routing with RIF.

Router(config-if)# standby [group-number] track type-number [interface-priority]

Configures the interface to track other interfaces, so that if one of the other interfaces goes down, the Hot Standby priority for the device is lowered.

Router(config-if)# standby [group-number] authentication string

Selects an authentication string to be carried in all HSRP messages.

Command Purpose

Command PurposeRouter(config)# ip routing Enables IP routing on the router.

Command Purpose


Specifies the subinterface on which TRISL will be used.

Step 2 Router(config-if)# encapsulation tr-isl trbrf-vlan vlanid bridge-num bridge-number

Defines the encapsulation for TRISL.



Assigning IP Address to Network Interface

An interface can have one primary IP address. To assign a primary IP address and a network mask to a network interface, use the following command in interface configuration mode:

A mask identifies the bits that denote the network number in an IP address. When you use the mask to subnet a network, the mask is then referred to as a subnet mask.

Note TRISL encapsulation must be specified for a subinterface before an IP address can be assigned to that subinterface.

Configuring IPX Routing on 802.10 VLANs over ISLThe IPX Encapsulation for 802.10 VLAN feature provides configurable IPX (Novell-FDDI, SAP, SNAP) encapsulation over 802.10 VLAN on router FDDI interfaces to connect the Catalyst 5000 VLAN switch. This feature extends Novell NetWare routing capabilities to include support for routing all standard IPX encapsulations for Ethernet frame types in VLAN configurations. Users with Novell NetWare environments can now configure any one of the three IPX Ethernet encapsulations to be routed using Secure Data Exchange (SDE) encapsulation across VLAN boundaries. IPX encapsulation options now supported for VLAN traffic include the following:

• Novell-FDDI (IPX FDDI RAW to 802.10 on FDDI)

• SAP (IEEE 802.2 SAP to 802.10 on FDDI)

• SNAP (IEEE 802.2 SNAP to 802.10 on FDDI)

NetWare users can now configure consolidated VLAN routing over a single VLAN trunking FDDI interface. Not all IPX encapsulations are currently supported for SDE VLAN. The IPX interior encapsulation support can be achieved by messaging the IPX header before encapsulating in the SDE format. Fast switching will also support all IPX interior encapsulations on non-MCI platforms (for example non-AGS+ and non-7000). With configurable Ethernet encapsulation protocols, users have the flexibility of using VLANs regardless of their NetWare Ethernet encapsulation. Configuring Novell IPX encapsulations on a per-VLAN basis facilitates migration between versions of Netware. NetWare traffic can now be routed across VLAN boundaries with standard encapsulation options (arpa, sap, and snap) previously unavailable. Encapsulation types and corresponding framing types are described in the “Configuring Novell IPX” chapter of the Cisco IOS AppleTalk and Novell IPX Configuration Guide.

Note Only one type of IPX encapsulation can be configured per VLAN (subinterface). The IPX encapsulation used must be the same within any particular subnet; a single encapsulation must be used by all NetWare systems that belong to the same VLAN.

Command Purpose

Router(config-if)# ip address ip-address mask Sets a primary IP address for an interface.



To configure Cisco IOS software on a router with connected VLANs to exchange different IPX framing protocols, perform the tasks described in the following sections in the order in which they are appear:

• Enabling NetWare Routing


• Configuring NetWare on the Subinterface

Enabling NetWare Routing

To enable IPX routing on SDE interfaces, use the following command in global configuration mode:


To define the encapsulation format as SDE, use the following commands in interface configuration mode:

Configuring NetWare on the Subinterface

After you enable NetWare globally and define the VLAN encapsulation format, to enable the subinterface by specifying the NetWare network number (if necessary) and the encapsulation type, use the following command in interface configuration mode:

Configuring IPX Routing over TRISLThe IPX Routing over ISL VLANs feature extends Novell NetWare routing capabilities to include support for routing all standard IPX encapsulations for Ethernet frame types in VLAN configurations. Users with Novell NetWare environments can configure either SAP or SNAP encapsulations to be routed using the TRISL encapsulation across VLAN boundaries. The SAP (Novell Ethernet_802.2) IPX encapsulation is supported for VLAN traffic.

NetWare users can now configure consolidated VLAN routing over a single VLAN trunking interface. With configurable Ethernet encapsulation protocols, users have the flexibility of using VLANs regardless of their NetWare Ethernet encapsulation. Configuring Novell IPX encapsulations on a

Command Purpose

Router(config)# ipx routing [node] Enables IPX routing globally.

Command Purpose

Step 1 Router(config)# interface fddi slot/port.subinterface-number Specifies the subinterface on which SDE will be used.

Step 2 Router(config-if)# encapsulation sde vlan-identifier Defines the encapsulation format and specifies the VLAN identifier.

Command PurposeRouter(config-if)# ipx network network encapsulation encapsulation-type Specifies the IPX encapsulation among

Novell-FDDI, SAP, or SNAP.



per-VLAN basis facilitates migration between versions of Netware. NetWare traffic can now be routed across VLAN boundaries with standard encapsulation options (sap and snap) previously unavailable. Encapsulation types and corresponding framing types are described in the “Configuring Novell IPX” chapter of the Cisco IOS AppleTalk and Novell IPX Configuration Guide.

Note Only one type of IPX encapsulation can be configured per VLAN (subinterface). The IPX encapsulation used must be the same within any particular subnet: A single encapsulation must be used by all NetWare systems that belong to the same LANs.

To configure Cisco IOS software to exchange different IPX framing protocols on a router with connected VLANs, perform the tasks described in the following sections in the order in which they are appear:





To enable IPX routing on TRISL interfaces, use the following command in global configuration mode:


To define the encapsulation format as TRISL, use the following commands in interface configuration mode:


After you enable NetWare globally and define the VLAN encapsulation format, to enable the subinterface by specifying the NetWare network number (if necessary) and the encapsulation type, use the following command in interface configuration mode:

Command PurposeRouter(config)# ipx routing [node] Enables IPX routing globally.

Command Purpose


Specifies the subinterface on which TRISL will be used.

Step 2 Router(config-if)# encapsulation tr-isl trbrf-vlan trbrf-vlan bridge-num bridge-num

Defines the encapsulation for TRISL.

Command PurposeRouter(config-if)# ipx network network encapsulation encapsulation-type

Specifies the IPX encapsulation.



Note The default IPX encapsulation format for Cisco IOS routers is “novell-ether” (Novell Ethernet_802.3). If you are running Novell Netware 3.12 or 4.0, the new Novell default encapsulation format is Novell Ethernet_802.2 and you should configure the Cisco router with the IPX encapsulation format “sap.”

Configuring VIP Distributed Switching over ISLWith the introduction of the VIP distributed ISL feature, ISL encapsulated IP packets can be switched on Versatile Interface Processor (VIP) controllers installed on Cisco 7500 series routers.

The second generation VIP2 provides distributed switching of IP encapsulated in ISL in VLAN configurations. Where an aggregation route performs inter-VLAN routing for multiple VLANs, traffic can be switched autonomously on-card or between cards rather than through the central Route Switch Processor (RSP). Figure 79 shows the VIP distributed architecture of the Cisco 7500 series router.

Figure 79 Cisco 7500 Distributed Architecture

This distributed architecture allows incremental capacity increases by installation of additional VIP cards. Using VIP cards for switching the majority of IP VLAN traffic in multiprotocol environments substantially increases routing performance for the other protocols because the RSP offloads IP and can then be dedicated to switching the non-IP protocols.

VIP distributed switching offloads switching of ISL VLAN IP traffic to the VIP card, removing involvement from the main CPU. Offloading ISL traffic to the VIP card substantially improves networking performance. Because you can install multiple VIP cards in a router, VLAN routing capacity is increased linearly according to the number of VIP cards installed in the router.

FastEthernet

VLAN1,2,3

VLAN4,5,6

VLAN7,8,9

VLAN10,11,12

VLAN13,14,15

VLAN16,17,18

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Processor

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cache

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CyBus



To configure distributed switching on the VIP, you must first configure the router for IP routing. Perform the tasks described in the following sections in the order in which they appear:

• Enabling IP Routing

• Enabling VIP Distributed Switching

• Configuring ISL Encapsulation on the Subinterface

Enabling IP Routing

To enable IP routing, use the following command in global configuration mode:

Once you have IP routing enabled on the router, you can customize the characteristics to suit your environment. Refer to the IP configuration chapters in the Cisco IOS IP Routing Configuration Guide for guidelines on configuring IP.

Enabling VIP Distributed Switching

To enable VIP distributed switching, use the following commands beginning in interface configuration mode:

Configuring ISL Encapsulation on the Subinterface

To configure ISL encapsulation on the subinterface, use the following commands in interface configuration mode:

Configuring XNS Routing over ISLXNS can be routed over VLAN subinterfaces using the ISL VLAN encapsulation protocol. The XNS Routing over ISL Virtual LANs feature provides full-feature Cisco IOS software XNS support on a per-VLAN basis, allowing standard XNS capabilities to be configured on VLANs.

Command Purpose

Router(config)# ip routing Enables IP routing on the router.

Command Purpose

Step 1 Router(config-if)# interface type slot/port-adapter/port

Specifies the interface and interface configuration mode.

Step 2 Router(config-if)# ip route-cache distributed Enables VIP distributed switching of IP packets on the interface.

Command Purpose

Step 1 Router(config-if)# interface type slot/port-adapter/port

Specifies the interface, and enters interface configuration mode.

Step 2 Router(config-if)# encapsulation isl vlan-identifier Defines the encapsulation format as ISL, and specifies the VLAN identifier.



To route XNS over ISL VLANs, you need to configure ISL encapsulation on the subinterface. Perform the tasks described in the following sections in the order in which they appear:

• Enabling XNS Routing


• Configuring XNS on the Subinterface

Enabling XNS Routing

To configure XNS routing, use the following command in global configuration mode:


To define the VLAN encapsulation format, use the following commands in interface configuration mode:

Configuring XNS on the Subinterface

To enable XNS on the subinterface by specifying the XNS network number, use the following command in interface configuration mode:

Configuring CLNS Routing over ISLCLNS can be routed over VLAN subinterfaces using the ISL VLAN encapsulation protocol. The CLNS Routing over ISL Virtual LANs feature provides full-feature Cisco IOS software CLNS support on a per-VLAN basis, allowing standard CLNS capabilities to be configured on VLANs.

To route CLNS over ISL VLANs, you need to configure ISL encapsulation on the subinterface. Perform the tasks described in the following sections in the order in which they appear:

• Enabling CLNS Routing


• Configuring CLNS on the Subinterface

Command Purpose

Router(config)# xns routing [address] Enables XNS routing globally.

Command Purpose





Command PurposeRouter(config-if)# xns network [number] Enables XNS routing on the subinterface.



Enabling CLNS Routing

To configure CLNS routing, use the following command in global configuration mode:



Configuring CLNS on the Subinterface

To enable CLNS on the subinterface by specifying the CLNS network number, use the following command in interface configuration mode:

Configuring IS-IS Routing over ISLIS-IS routing can be enabled over VLAN subinterfaces using the ISL VLAN encapsulation protocol. The IS-IS Routing over ISL Virtual LANs feature provides full-feature Cisco IOS software IS-IS support on a per-VLAN basis, allowing standard IS-IS capabilities to be configured on VLANs.

To enable IS-IS over ISL VLANs, you need to configure ISL encapsulation on the subinterface. Perform the tasks described in the following sections in the order in which they appear:

• Enabling IS-IS Routing


• Configuring IS-IS on the Subinterface

Command Purpose

Router(config)# clns routing Enables CLNS routing globally.

Command Purpose





Command PurposeRouter(config-if)# clns enable Enables CLNS routing on the subinterface.

Configuring Routing Between VLANs with Inter-Switch Link EncapsulationISL Encapsulation Configuration Examples


Enabling IS-IS Routing

To configure IS-IS routing, use the following command in global configuration mode:



Configuring IS-IS on the Subinterface

To enable IS-IS on the subinterface by specifying the IS-IS network number, use the following command in interface configuration mode:

Monitoring and Maintaining VLAN SubinterfacesTo indicate whether a VLAN is a native VLAN, use the following command in privileged EXEC mode:

ISL Encapsulation Configuration ExamplesThis section provides the following configuration examples for each of the protocols described in this chapter:

• AppleTalk Routing over ISL Configuration Examples

• Banyan VINES Routing over ISL Configuration Example

• DECnet Routing over ISL Configuration Example

Command Purpose

Step 1 Router(config)# router isis [tag] Enables IS-IS routing, and enters router configuration mode.

Step 2 Router(config)# net network-entity-title Configures the NET for the routing process.

Command Purpose





Command PurposeRouter(config-if)# clns router isis network [tag] Specifies the interfaces that should be actively routing

IS-IS.

Command PurposeRouter# show vlans Displays VLAN subinterfaces.



• HSRP over ISL Configuration Example

• IP Routing with RIF Between TrBRF VLANs Example

• IP Routing Between a TRISL VLAN and an Ethernet ISL VLAN Example

• IPX Routing over ISL Configuration Example

• IPX Routing on FDDI Interfaces with SDE Example

• Routing with RIF Between a TRISL VLAN and a Token Ring Interface Example

• VIP Distributed Switching over ISL Configuration Example

• XNS Routing over ISL Configuration Example

• CLNS Routing over ISL Configuration Example

• IS-IS Routing over ISL Configuration Example

AppleTalk Routing over ISL Configuration ExamplesThe configuration example illustrated in Figure 80 shows AppleTalk being routed between different ISL and IEEE 802.10 VLAN encapsulating subinterfaces.

Figure 80 Routing AppleTalk over VLAN Encapsulations

As shown in Figure 80, AppleTalk traffic is routed to and from switched VLAN domains 3, 4, 100, and 200 to any other AppleTalk routing interface. This example shows a sample configuration file for the Cisco 7500 series router with the commands entered to configure the network shown in Figure 80.

Cisco 7500 Router Configuration!appletalk routinginterface Fddi 1/0.100 encapsulation sde 100

Wide-area linkCisco 7500

series router

Catalyst 5000 switchsupporting 2 AppleTalk

VLANs on FastEthernetconnections with ISL

encapsulation

FastEthernet 2/0100BASE-T ISL

VLAN 4Apple 4.1

VLAN 3Apple 3.1

Apple 100.1VLAN 100 FDDI VLAN backbone using

802.10 encapsulation format

FDDI SDEfddi 1/0

Apple 200.1VLAN 200

Catalyst 1200

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appletalk cable-range 100-100 100.2 appletalk zone 100!interface Fddi 1/0.200 encapsulation sde 200 appletalk cable-range 200-200 200.2 appletalk zone 200!interface FastEthernet 2/0.3encapsulation isl 3

appletalk cable-range 3-3 3.2 appletalk zone 3!interface FastEthernet 2/0.4encapsulation isl 4

appletalk cable-range 4-4 4.2 appletalk zone 4!

Banyan VINES Routing over ISL Configuration ExampleTo configure routing of the Banyan VINES protocol over ISL trunks, you need to define ISL as the encapsulation type. This example shows Banyan VINES configured to be routed over an ISL trunk:

vines routinginterface fastethernet 0.1encapsulation isl 100vines metric 2

DECnet Routing over ISL Configuration ExampleTo configure routing the DECnet protocol over ISL trunks, you need to define ISL as the encapsulation type. This example shows DECnet configured to be routed over an ISL trunk:

decnet routing 2.1interface fastethernet 1/0.1encapsulation isl 200decnet cost 4

HSRP over ISL Configuration ExampleThe configuration example shown in Figure 81 shows HSRP being used on two VLAN routers sending traffic to and from ISL VLANs through a Catalyst 5000 switch. Each router forwards its own traffic and acts as a standby for the other.



Figure 81 Hot Standby Router Protocol Sample Configuration

The topology shown in Figure 81 shows a Catalyst VLAN switch supporting Fast Ethernet connections to two routers running HSRP. Both routers are configured to route HSRP over ISLs.

The standby conditions are determined by the standby commands used in the configuration. Traffic from Host 1 is forwarded through Router A. Because the priority for the group is higher, Router A is the active router for Host 1. Because the priority for the group serviced by Host 2 is higher in Router B, traffic from Host 2 is forwarded through Router B, making Router B its active router.

In the configuration shown in Figure 81, if the active router becomes unavailable, the standby router assumes active status for the additional traffic and automatically routes the traffic normally handled by the router that has become unavailable.

Host 1 Configurationinterface Ethernet 1/2ip address 10.1.1.25 255.255.255.0ip route 0.0.0.0 0.0.0.0 10.1.1.101

Host 2 Configurationinterface Ethernet 1/2ip address 10.1.1.27 255.255.255.0ip route 0.0.0.0 0.0.0.0 10.1.1.102

!

Router A Configurationinterface FastEthernet 1/1.110encapsulation isl 110ip address 10.1.1.2 255.255.255.0standby 1 ip 10.1.1.101standby 1 preemptstandby 1 priority 105standby 2 ip 10.1.1.102standby 2 preempt

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Enterprisenetwork

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FE 1/1FE 1/1

Port 2/8

Port 5/3

Port 2/9

Port 5/4

ISL VLAN 110

Catalyst VLANswitch

Ethernet 1/2

Ethernet 1/2

Ethernet 1/2

Ethernet 1/2

Host 1 Host 2

Cisco IOS Router Aon FastEthernet

ISL connection to aCatalyst 5000 switch

Cisco IOS Router Bon FastEthernetISL connection to aCatalyst 5000 switch

Cisco IOSCisco IOS



!end

!

Router B Configurationinterface FastEthernet 1/1.110encapsulation isl 110ip address 10.1.1.3 255.255.255.0standby 1 ip 10.1.1.101standby 1 preemptstandby 2 ip 10.1.1.102standby 2 preemptstandby 2 priority 105

router igrp 1!network 10.1.0.0network 10.2.0.0!

VLAN Switch Configurationset vlan 110 5/4set vlan 110 5/3set trunk 2/8 110set trunk 2/9 110

IP Routing with RIF Between TrBRF VLANs ExampleFigure 82 shows IP routing with RIF between two TrBRF VLANs.

Figure 82 IP Routing with RIF Between TrBRF VLANs

The following is the configuration for the router:

interface FastEthernet4/0.1ip address 10.5.5.1 255.255.255.0encapsulation tr-isl trbrf-vlan 999 bridge-num 14multiring trcrf-vlan 200 ring 100multiring all

Catalyst5000 switch

5500

1125

0

End station

TokenRing103

End station

TrBRF 998 / Bridge 13

TrBRF 999 / Bridge 14Router

101

100

TokenRing102

Fast Ethernet 4/0.1

Fast Ethernet 4/0.2

Token Ringswitch module

5.5.5.1

4.4.4.1

TrCRF VLAN 40Slot 5Port 1


TrCRF 300

TrCRF 200



!interface FastEthernet4/0.2ip address 10.4.4.1 255.255.255.0encapsulation tr-isl trbrf-vlan 998 bridge-num 13multiring trcrf-vlan 300 ring 101multiring all

The following is the configuration for the Catalyst 5000 switch with the Token Ring switch module in slot 5. In this configuration, the Token Ring port 102 is assigned with TrCRF VLAN 40 and the Token Ring port 103 is assigned with TrCRF VLAN 50:

#vtpset vtp domain trislset vtp mode serverset vtp v2 enable#dripset set tokenring reduction enableset tokenring distrib-crf disable#vlansset vlan 999 name trbrf type trbrf bridge 0xe stp ieeeset vlan 200 name trcrf200 type trcrf parent 999 ring 0x64 mode srbset vlan 40 name trcrf40 type trcrf parent 999 ring 0x66 mode srbset vlan 998 name trbrf type trbrf bridge 0xd stp ieeeset vlan 300 name trcrf300 type trcrf parent 998 ring 0x65 mode srbset vlan 50 name trcrf50 type trcrf parent 998 ring 0x67 mode srb#add token port to trcrf 40set vlan 40 5/1#add token port to trcrf 50set vlan 50 5/2set trunk 1/2 on

IP Routing Between a TRISL VLAN and an Ethernet ISL VLAN ExampleFigure 83 shows IP routing between a TRISL VLAN and an Ethernet ISL VLAN.

Figure 83 IP Routing Between a TRISL VLAN and an Ethernet ISL VLAN


interface FastEthernet4/0.1ip address 10.5.5.1 255.255.255.0encapsulation tr-isl trbrf-vlan 999 bridge-num 14multiring trcrf-vlan 20 ring 100multiring all

!

End station

End station

Ethernet ISL VLAN 12

5.5.5.1

4.4.4.1

TrBRF 999 / Bridge 14

Router A

1125

1

Token Ring switch modulein slot 5

TrCRF100Slot 5Port 1

Ethernetmodulein slot 2

Catalyst5000 switch

5500

TokenRing

1100

TrCRF 200



interface FastEthernet4/0.2ip address 10.4.4.1 255.255.255.0encapsulation isl 12

IPX Routing over ISL Configuration ExampleFigure 84 shows IPX interior encapsulations configured over ISL encapsulation in VLAN configurations. Note that three different IPX encapsulation formats are used. VLAN 20 uses SAP encapsulation, VLAN 30 uses ARPA, and VLAN 70 uses novell-ether encapsulation. Prior to the introduction of this feature, only the default encapsulation format, “novell-ether,” was available for routing IPX over ISL links in VLANs.

Figure 84 Configurable IPX Encapsulations Routed over ISL in VLAN Configurations

VLAN 20 Configuration ipx routinginterface FastEthernet 2/0 no shutdown

interface FastEthernet 2/0.20encapsulation isl 20ipx network 20 encapsulation sap

Wide-area linkcarrying VLAN traffic

Workstation Con an IPX LAN

with novell-etherencapsulation

VLAN 70VLAN 20

VLAN 30

FE 2/0

Catalyst5000 switch

Catalyst2900 switch

FE 3/0

Fast Ethernet linkscarrying ISL traffic

Workstation Aunning NetWare 4.0on an IPX LAN withsap encapsulation

Workstation Bon an IPX LAN witharpa encapsulation S

6240

Cisco 7200 routerrunning traffic

between VLANsRSP



VLAN 30 Configurationipx routinginterface FastEthernet 2/0 no shutdown

interface FastEthernet 2/0.30encapsulation isl 30ipx network 30 encapsulation arpa

VLAN 70 Configurationipx routinginterface FastEthernet 3/0no shutdown

interface Fast3/0.70encapsulation isl 70ipx network 70 encapsulation novell-ether

IPX Routing on FDDI Interfaces with SDE ExampleThe following example enables IPX routing on FDDI interfaces 0.2 and 0.3 with SDE. On FDDI interface 0.2, the encapsulation type is SNAP. On FDDI interface 0.3, the encapsulation type is Novell’s FDDI_RAW.

ipx routing

interface fddi 0.2 enc sde 2ipx network f02 encapsulation snap

interface fddi 0.3 enc sde 3ipx network f03 encapsulation novell-fddi

Routing with RIF Between a TRISL VLAN and a Token Ring Interface ExampleFigure 85 shows routing with RIF between a TRISL VLAN and a Token Ring interface.

Figure 85 Routing with RIF Between a TRISL VLAN and a Token Ring Interface

1077

7

Fast Ethernet 4/0.1

5.5.5.14.4.4.1

100

Catalyst 5000 switch

5500Token Ringswitchmodule


TrBRF 999 / Bridge 14TrCRF 200

End station

TokenRing 1

End station

End station

End station

TokenRing 2




source-bridge ring-group 100!interface TokenRing 3/1ip address 10.4.4.1 255.255.255.0

!interface FastEthernet4/0.1ip address 10.5.5.1 255.255.255.0encapsulation tr-isl trbrf 999 bridge-num 14multiring trcrf-vlan 200 ring-group 100multiring all

The following is the configuration for the Catalyst 5000 switch with the Token Ring switch module in slot 5. In this configuration, the Token Ring port 1 is assigned to the TrCRF VLAN 40:

#vtpset vtp domain trislset vtp mode serverset vtp v2 enable#dripset set tokenring reduction enableset tokenring distrib-crf disable#vlansset vlan 999 name trbrf type trbrf bridge 0xe stp ieeeset vlan 200 name trcrf200 type trcrf parent 999 ring 0x64 mode srtset vlan 40 name trcrf40 type trcrf parent 999 ring 0x1 mode srt#add token port to trcrf 40set vlan 40 5/1set trunk 1/2 on

VIP Distributed Switching over ISL Configuration ExampleFigure 86 shows a topology in which Catalyst VLAN switches are connected to routers forwarding traffic from a number of ISL VLANs. With the VIP distributed ISL capability in the Cisco 7500 series router, each VIP card can route ISL-encapsulated VLAN IP traffic. The inter-VLAN routing capacity is increased linearly by the packet-forwarding capability of each VIP card.



Figure 86 VIP Distributed ISL VLAN Traffic

In Figure 86, the VIP cards forward the traffic between ISL VLANs or any other routing interface. Traffic from any VLAN can be routed to any of the other VLANs, regardless of which VIP card receives the traffic.

These commands show the configuration for each of the VLANs shown in Figure 86:

interface FastEthernet1/0/0 ip address 10.1.1.1 255.255.255.0 ip route-cache distributed full-duplex

interface FastEthernet1/0/0.1 ip address 10.1.1.1 255.255.255.0 encapsulation isl 1



interface FastEthernet1/1/0 ip route-cache distributed full-duplex


FE

VIP

CyBus

Fast Ethernetport adapters

Cisco 7500 series router withVIP2 or later cards routing

traffic between VLANs

Catalyst VLANswitches forwardingISL VLAN traffic

FE FEFE

S62

38ISL VLAN 1 ISL VLAN 2 ISL VLAN 3 ISL VLAN 4 ISL VLAN 5

WAN

ISL VLAN 6 ISL VLAN 7

Fast Ethernet linkscarrying ISL VLAN traffic

RSP

VIP



interface Fast Ethernet 2/0/0ip address 10.1.1.1 255.255.255.0ip route-cache distributedfull-duplex


interface FastEthernet2/1/0 ip address 10.3.1.1 255.255.255.0 ip route-cache distributed full-duplex



XNS Routing over ISL Configuration ExampleTo configure routing of the XNS protocol over ISL trunks, you need to define ISL as the encapsulation type. This example shows XNS configured to be routed over an ISL trunk:

xns routing 0123.4567.adcbinterface fastethernet 1/0.1encapsulation isl 100xns network 20

CLNS Routing over ISL Configuration ExampleTo configure routing of the CLNS protocol over ISL trunks, you need to define ISL as the encapsulation type. This example shows CLNS configured to be routed over an ISL trunk:

clns routing interface fastethernet 1/0.1encapsulation isl 100clns enable

IS-IS Routing over ISL Configuration ExampleTo configure IS-IS routing over ISL trunks, you need to define ISL as the encapsulation type. This example shows IS-IS configured over an ISL trunk:

isis routing test-proc2net 49.0001.0002.aaaa.aaaa.aaaa.00interface fastethernet 2.0encapsulation isl 101clns router is-is test-proc2


Configuring Routing Between VLANs with IEEE 802.10 Encapsulation

This chapter describes the required and optional tasks for configuring routing between VLANs with IEEE 802.10 encapsulation.



The IEEE 802.10 standard provides a method for secure bridging of data across a shared backbone. It defines a single frame type known as the Secure Data Exchange (SDE), a MAC-layer frame with an IEEE 802.10 header inserted between the MAC header and the frame data. A well-known Logical Link Control Service Access Point notifies the switch of an incoming IEEE 802.10 frame. The VLAN ID is carried in the 4-byte security association identifier (SAID) field.

HDLC Serial links can be used as VLAN trunks in IEEE 802.10 VLANs to extend a virtual topology beyond a LAN backbone.

Configuring AppleTalk Routing over IEEE 802.10 AppleTalk can be routed over VLAN subinterfaces using the ISL or IEEE 802.10 VLANs feature that provides full-feature Cisco IOS software AppleTalk support on a per-VLAN basis, allowing standard AppleTalk capabilities to be configured on VLANs.

AppleTalk users can now configure consolidated VLAN routing over a single VLAN trunking interface. Prior to introduction of this feature, AppleTalk could be routed only on the main interface on a LAN port. If AppleTalk routing was disabled on the main interface or if the main interface was shut down, the entire physical interface would stop routing any AppleTalk packets. With this feature enabled, AppleTalk routing on subinterfaces will be unaffected by changes in the main interface with the main interface in the “no-shut” state.

Configuring Routing Between VLANs with IEEE 802.10 EncapsulationConfiguring AppleTalk Routing over IEEE 802.10


To route AppleTalk over IEEE 802.10 between VLANs, create the environment in which it will be used by customizing the subinterface and perform the tasks described in the following sections in the order in which they appear:




• Monitoring and Maintaining VLAN Subinterfaces

Enabling AppleTalk RoutingTo enable AppleTalk routing on IEEE 802.10 interfaces, use the following command in global configuration mode:

Note For more information on configuring AppleTalk, see the “Configuring AppleTalk” chapter in the Cisco IOS AppleTalk and Novell IPX Configuration Guide.

Configuring AppleTalk on the SubinterfaceAfter you enable AppleTalk globally and define the encapsulation format, you need to enable it on the subinterface by specifying the cable range and naming the AppleTalk zone for each interface. To enable the AppleTalk protocol on the subinterface, use the following commands in interface configuration mode:

Command PurposeRouter(config)# appletalk routing [eigrp router-number] Enables AppleTalk routing globally.

Command Purpose

Router(config-if)# appletalk cable-range cable-range [network.node]


Router(config-if)# appletalk zone zone-name Assigns the AppleTalk zone for the subinterface.

Configuring Routing Between VLANs with IEEE 802.10 EncapsulationRouting AppleTalk over IEEE 802.10 Configuration Example


Defining the VLAN Encapsulation FormatTo define the VLAN encapsulation format as either ISL or 802.10, use the following commands in interface configuration mode:


Routing AppleTalk over IEEE 802.10 Configuration ExampleThe configuration example shown in Figure 87 shows AppleTalk being routed between different ISL and IEEE 802.10 VLAN encapsulating subinterfaces.

Figure 87 Routing AppleTalk over VLAN encapsulations

Command Purpose



Step 2 Router(config-if)# encapsulation sde said Defines the encapsulation format as IEEE 802.10 (sde) and specifies the VLAN identifier or security association identifier, respectively.

Command PurposeRouter# show vlans Displays VLAN subinterfaces.

Wide-area linkCisco 7500

series router

Catalyst 5000 switchsupporting 2 AppleTalk

VLANs on FastEthernetconnections with ISL

encapsulation

FastEthernet 2/0100BASE-T ISL

VLAN 4Apple 4.1

VLAN 3Apple 3.1

Apple 100.1VLAN 100 FDDI VLAN backbone using

802.10 encapsulation format

FDDI SDEfddi 1/0

Apple 200.1VLAN 200

Catalyst 1200

S62

41

Configuring Routing Between VLANs with IEEE 802.10 EncapsulationRouting AppleTalk over IEEE 802.10 Configuration Example


As shown in Figure 87, AppleTalk traffic is routed to and from switched VLAN domains 3, 4, 100, and 200 to any other AppleTalk routing interface. This example shows a sample configuration file for the Cisco 7500 series router with the commands entered to configure the network shown in Figure 87.

Cisco 7500 Router Configuration!interface Fddi 1/0.100 encapsulation sde 100 appletalk cable-range 100-100 100.2 appletalk zone 100!interface Fddi 1/0.200 encapsulation sde 200 appletalk cable-range 200-200 200.2 appletalk zone 200!interface FastEthernet 2/0.3encapsulation isl 3

appletalk cable-range 3-3 3.2 appletalk zone 3!interface FastEthernet 2/0.4encapsulation isl 4

appletalk cable-range 4-4 4.2 appletalk zone 4!


Configuring Routing Between VLANs with IEEE 802.1Q Encapsulation

This chapter describes the required and optional tasks for configuring routing between VLANs with IEEE 802.1Q encapsulation.



The IEEE 802.1Q protocol is used to interconnect multiple switches and routers, and for defining VLAN topologies. The IEEE 802.1Q standard is extremely restrictive to untagged frames. The standard provides only a per-port VLANs solution for untagged frames. For example, assigning untagged frames to VLANs takes into consideration only the port from which they have been received. Each port has a parameter called a permanent virtual identification (Native VLAN) that specifies the VLAN assigned to receive untagged frames.

The main characteristics of IEEE 802.1Q are as follows:

• Assigns frames to VLANs by filtering.

• The standard assumes the presence of a single spanning tree and of an explicit tagging scheme with one-level tagging.

IEEE 802.1Q Encapsulation VLANs Configuration Task ListYou can configure routing between any number of VLANs in your network.

This section documents the configuration tasks for each protocol supported with IEEE 802.1Q encapsulation. The basic process is the same, regardless of the protocol being routed. It involves the following tasks:

• Enabling the protocol on the router

• Enabling the protocol on the interface

• Defining the encapsulation format as IEEE 802.1Q

• Customizing the protocol according to the requirements for your environment

Configuring Routing Between VLANs with IEEE 802.1Q EncapsulationIEEE 802.1Q Encapsulation VLANs Configuration Task List


To configure IEEE 802.1Q of your network, perform the tasks described in the following sections. The first three sections contain required tasks; the remaining tasks are optional:

• Configuring AppleTalk Routing over IEEE 802.1Q (Required)

• Configuring IP Routing over IEEE 802.1Q (Required)

• Configuring IPX Routing over IEEE 802.1Q (Required)

Perform the tasks in the following sections to connect a network of hosts over a simple bridging-access device to a remote access concentrator bridge between IEEE 802.1Q VLANs. The following sections contain configuration tasks for the Integrated Routing and Bridging, Transparent Bridging, and PVST+ Between VLANs with IEEE 802.1Q Encapsulation feature:

• Configuring a VLAN for a bridge-group with Default VLAN1(Optional)

• Configuring a VLAN for a bridge-group as a Native VLAN (Optional)

• Monitoring and Maintaining VLAN Subinterfaces (Optional)

Configuring AppleTalk Routing over IEEE 802.1Q AppleTalk can be routed over virtual LAN (VLAN) subinterfaces using the IEEE 802.1Q VLAN encapsulation protocol. AppleTalk Routing provides full-feature Cisco IOS software AppleTalk support on a per-VLAN basis, allowing standard AppleTalk capabilities to be configured on VLANs.

To route AppleTalk over IEEE 802.1Q between VLANs, you need to customize the subinterface to create the environment in which it will be used. Perform these tasks in the order in which they appear:




Enabling AppleTalk Routing

To enable AppleTalk routing on IEEE 802.1Q interfaces, use the following command in global configuration mode:

Note For more information on configuring AppleTalk, see the “Configuring AppleTalk” chapter in the Cisco IOS AppleTalk and Novell IPX Configuration Guide.

Command PurposeRouter(config)# appletalk routing [eigrp router-number] Enables AppleTalk routing globally.



Configuring AppleTalk on the Subinterface

After you enable AppleTalk globally and define the encapsulation format, you need to enable it on the subinterface by specifying the cable range and naming the AppleTalk zone for each interface. To enable the AppleTalk protocol on the subinterface, use the following commands in interface configuration mode:


To define the VLAN encapsulation format as IEEE 802.1Q, use the following commands in interface configuration mode:

Configuring IP Routing over IEEE 802.1QIP routing over IEEE 802.1Q extends IP routing capabilities to include support for routing IP frame types in VLAN configurations using the IEEE 802.1Q encapsulation.

To route IP over IEEE 802.1Q between VLANs, you need to customize the subinterface to create the environment in which it will be used. Perform the tasks described in the following sections in the order in which they appear:

• Enabling IP Routing


• Assigning an IP Address to Network Interface

Enabling IP Routing

IP routing is automatically enabled in the Cisco IOS software for routers. To reenable IP routing if it has been disabled, use the following command in global configuration mode:

Command Purpose

Step 1 Router(config-if)# appletalk cable-range cable-range [network.node]


Step 2 Router(config-if)# appletalk zone zone-name Assigns the AppleTalk zone for the subinterface.

Command Purpose

Step 1 Router(config-if)# interface fastethernet slot/port.subinterface-number


Step 2 Router(config-if)# encapsulation dot1q vlan-identifier

Defines the encapsulation format as IEEE 802.1Q (dot1q), and specifies the VLAN identifier.

Command PurposeRouter(config)# ip routing Enables IP routing on the router.



Once you have IP routing enabled on the router, you can customize the characteristics to suit your environment. If necessary, refer to the IP configuration chapters in the Cisco IOS IP Routing Configuration Guide for guidelines on configuring IP.


To define the encapsulation format as IEEE 802.1Q, use the following commands in interface configuration mode:

Assigning an IP Address to Network Interface

An interface can have one primary IP address. To assign a primary IP address and a network mask to a network interface, use the following command in interface configuration mode:

A mask identifies the bits that denote the network number in an IP address. When you use the mask to subnet a network, the mask is then referred to as a subnet mask.

Configuring IPX Routing over IEEE 802.1QIPX routing over IEEE 802.1Q VLANs extends Novell NetWare routing capabilities to include support for routing Novell Ethernet_802.3 encapsulation frame types in VLAN configurations. Users with Novell NetWare environments can configure Novell Ethernet_802.3 encapsulation frames to be routed using IEEE 802.1Q encapsulation across VLAN boundaries.

To configure Cisco IOS software on a router with connected VLANs to exchange IPX Novell Ethernet_802.3 encapsulated frames, perform the tasks described in the following sections in the order in which they are appear:




Command Purpose


Specifies the subinterface on which IEEE 802.1Q will be used.

Step 2 Router(config-if)# encapsulation dot1q vlanid Defines the encapsulation format as IEEE 802.1Q (dot1q), and specifies the VLAN identifier

Command PurposeRouter(config-if)# ip address ip-address mask Sets a primary IP address for an interface.




To enable IPX routing on IEEE 802.1Q interfaces, use the following command in global configuration mode:


To define the encapsulation format as IEEE 802.1Q, use the following commands in interface configuration mode:


After you enable NetWare globally and define the VLAN encapsulation format, you may need to enable the subinterface by specifying the NetWare network number. Use this command in interface configuration mode:

Configuring a VLAN for a bridge-group with Default VLAN1To configure a VLAN associated to a bridge group with a default native VLAN, use the following commands beginning in global configuration mode:

Note If there is no explicitly defined native VLAN, the default VLAN 1 becomes the native VLAN 1.

Command Purpose

Router(config)# ipx routing [node] Enables IPX routing globally.

Command Purpose


Specifies the subinterface on which IEEE 802.1Q will be used.

Step 2 Router(config-if)# encapsulation dot1q vlan-identifier

Defines the encapsulation format as IEEE 802.1Q and specifies the VLAN identifier.

Command PurposeRouter(config-if)# ipx network network Specifies the IPX network number.

Command Purpose

Step 1 Router(config)# interface fastethernet slot/port Selects a particular Fast Ethernet interface for configuration.

Step 2 Router(config-subif)# encapsulation dot1q 1 Enables IEEE 802.1Q encapsulation of traffic on a specified subinterface in VLANs, and defaults the associated VLAN as a native VLAN.

Step 3 Router(config-subif)# bridge-group bridge-group Assigns each network interface to a bridge group.

Configuring Routing Between VLANs with IEEE 802.1Q EncapsulationIEEE 802.1Q Encapsulation Configuration Examples


Configuring a VLAN for a bridge-group as a Native VLANTo configure a VLAN associated to a bridge group as a native VLAN, use the following beginning commands in global configuration mode:

Note If there is an explicitly defined native VLAN, VLAN 1 will only be used to process CST.


IEEE 802.1Q Encapsulation Configuration ExamplesConfiguration examples for each protocols are provided in the following sections:

• !Configuring AppleTalk over IEEE 802.1Q Example

• Configuring IP Routing over IEEE 802.1Q Example

• Configuring IPX Routing over IEEE 802.1Q Example

• VLAN 100 for Bridge Group 1 with Default VLAN 1 Example

• VLAN 20 for Bridge Group 1 with Native VLAN Example

• VLAN ISL or IEEE 802.1Q Routing Example

• VLAN IEEE 802.1Q Bridging Example

• VLAN IEEE 802.1Q IRB Example

Command Purpose

Step 1 Router(config)# interface fastethernet slot/port Selects a particular Fast Ethernet interface for configuration.

Step 2 Router(config-subif)# encapsulation dot1q vlan-id native

Enables IEEE 802.1Q encapsulation of traffic on a specified subinterface in VLANs, and defaults to 1.

Step 3 Router(config-subif)# bridge-group bridge-group Assigns each network interface to a bridge group.

Command Purpose

Router# show vlans Displays VLAN subinterfaces.



Configuring AppleTalk over IEEE 802.1Q ExampleThis configuration example shows AppleTalk being routed on VLAN 100:

!appletalk routing!interface fastethernet 4/1.100

encapsulation dot1q 100appletalk cable-range 100-100 100.1appletalk zone eng

!

Configuring IP Routing over IEEE 802.1Q ExampleThis configuration example shows IP being routed on VLAN 101:

!ip routing!interface fastethernet 4/1.101

encapsulation dot1q 101ip addr 10.0.0.11 255.0.0.0

!

Configuring IPX Routing over IEEE 802.1Q ExampleThis configuration example shows IPX being routed on VLAN 102:

!ipx routing!interface fastethernet 4/1.102

encapsulation dot1q 102ipx network 100

!

VLAN 100 for Bridge Group 1 with Default VLAN 1 ExampleThe following example configures VLAN 100 for bridge group 1 with a default VLAN 1:

interface FastEthernet 4/1.100encapsulation dot1q 1bridge-group 1

VLAN 20 for Bridge Group 1 with Native VLAN ExampleThe following example configures VLAN 20 for bridge group 1 as a native VLAN:

interface FastEthernet 4/1.100encapsulation dot1q 20 nativebridge-group 1



VLAN ISL or IEEE 802.1Q Routing ExampleThe following example configures VLAN ISL or IEEE 802.10 routing:

ipx routingappletalk routing!interface Ethernet 1ip address 10.1.1.1 255.255.255.0appletalk cable-range 1-1 1.1appletalk zone 1ipx network 10 encapsulation snap!router igrp 1network 10.1.0.0!end!#Catalyst5000!set VLAN 110 2/1set VLAN 120 2/2!set trunk 1/1 110,120# if 802.1Q, set trunk 1/1 nonegotiate 110, 120!end!

ipx routingappletalk routing!interface FastEthernet 1/1.110encapsulation isl 110!if 802.1Q, encapsulation dot1Q 110ip address 10.1.1.2 255.255.255.0appletalk cable-range 1.1 1.2appletalk zone 1ipx network 110 encapsulation snap!interface FastEthernet 1/1.120encapsulation isl 120!if 802.1Q, encapsulation dot1Q 120ip address 10.2.1.2 255.255.255.0appletalk cable-range 2-2 2.2appletalk zone 2ipx network 120 encapsulation snap!router igrp 1network 10.1.0.0network 10.2.1.0.0!end!

ipx routingappletalk routing!interface Ethernet 1ip address 10.2.1.3 255.255.255.0appletalk cable-range 2-2 2.3appletalk zone 2ipx network 120 encapsulation snap



!router igrp 1network 10.2.0.0!end

VLAN IEEE 802.1Q Bridging ExampleThe following examples configures IEEE 802.1Q bridging:

interface FastEthernet4/0 no ip address no ip route-cache half-duplex!interface FastEthernet4/0.100 encapsulation dot1Q 100 no ip route-cache bridge-group 1!interface FastEthernet4/0.200 encapsulation dot1Q 200 native no ip route-cache bridge-group 2!interface FastEthernet4/0.300 encapsulation dot1Q 1 no ip route-cache bridge-group 3!interface FastEthernet10/0 no ip address no ip route-cache half-duplex!interface FastEthernet10/0.100 encapsulation dot1Q 100 no ip route-cache bridge-group 1!interface Ethernet11/3 no ip address no ip route-cache bridge-group 2!interface Ethernet11/4 no ip address no ip route-cache bridge-group 3!bridge 1 protocol ieeebridge 2 protocol ieeebridge 3 protocol ieee



VLAN IEEE 802.1Q IRB ExampleThe following examples configures IEEE 802.1Q integrated routing and bridging:

ip cefappletalk routingipx routing 0060.2f27.5980!bridge irb!interface TokenRing3/1 no ip address ring-speed 16 bridge-group 2!interface FastEthernet4/0 no ip address half-duplex!interface FastEthernet4/0.100 encapsulation dot1Q 100 bridge-group 1!interface FastEthernet4/0.200 encapsulation dot1Q 200 bridge-group 2!interface FastEthernet10/0ip address 10.3.1.10 255.255.255.0 half-duplex appletalk cable-range 200-200 200.10 appletalk zone irb ipx network 200!interface Ethernet11/3 no ip address bridge-group 1!interface BVI 1 ip address 10.1.1.11 255.255.255.0 appletalk cable-range 100-100 100.11 appletalk zone bridging ipx network 100!router rip network 10.0.0.0 network 10.3.0.0!bridge 1 protocol ieee bridge 1 route appletalk bridge 1 route ip bridge 1 route ipxbridge 2 protocol ieee!

LAN Emulation


LAN Emulation Overview

This overview chapter gives a high-level description of LAN Emulation (LANE).

Procedures for configuring LANE are provided in the following chapters in this publication:

• “Configuring LAN Emulation” chapter

• “Configuring Token Ring LAN Emulation” chapter

LAN EmulationThe Cisco implementation of LANE makes an ATM interface look like one or more Ethernet interfaces.

LANE is an ATM service defined by the ATM Forum specification LAN Emulation over ATM, ATM_FORUM 94-0035. This service emulates the following LAN-specific characteristics:

• Connectionless services

• Multicast services

• LAN MAC driver services

LANE service provides connectivity between ATM-attached devices and connectivity with LAN-attached devices. This includes connectivity between ATM-attached stations and LAN-attached stations and also connectivity between LAN-attached stations across an ATM network.

Because LANE connectivity is defined at the MAC layer, upper protocol-layer functions of LAN applications can continue unchanged when the devices join emulated LANs (ELANs). This feature protects corporate investments in legacy LAN applications.

An ATM network can support multiple independent ELAN networks. Membership of an end system in any of the ELANs is independent of the physical location of the end system. This characteristic enables easy hardware moves and location changes. In addition, the end systems can also move easily from one ELAN to another, whether or not the hardware moves.

LANE in an ATM environment provides routing between ELANs for supported routing protocols and high-speed, scalable switching of local traffic.

The ATM LANE system has three servers that are single points of failure. These are the LANE Configuration Server (LECS), the ELAN server (LES), and the broadcast and unknown server (BUS). Beginning with Cisco IOS Release 11.2, LANE fault tolerance or Simple LANE Service Replication on the ELAN provides backup servers to prevent problems if these servers fail.

The fault tolerance mechanism that eliminates these single points of failure is described in the “Configuring LAN Emulation” chapter. Although this scheme is proprietary, no new protocol additions have been made to the LANE subsystems.

LAN Emulation OverviewLAN Emulation


LANE ComponentsAny number of ELANs can be set up in an ATM switch cloud. A router can participate in any number of these ELANs.

LANE is defined on a LAN client/server model. The following components are implemented:

• LANE client—A LANE client emulates a LAN interface to higher layer protocols and applications. It forwards data to other LANE components and performs LANE address resolution functions.

Each LANE client is a member of only one ELAN. However, a router can include LANE clients for multiple ELANs: one LANE client for each ELAN of which it is a member.

If a router has clients for multiple ELANs, the Cisco IOS software can route traffic between the ELANs.

• LES—The LES for an ELAN is the control center. It provides joining, address resolution, and address registration services to the LANE clients in that ELAN. Clients can register destination unicast and multicast MAC addresses with the LES. The LES also handles LANE ARP (LE ARP) requests and responses.

The Cisco implementation has a limit of one LES per ELAN.

• LANE BUS—The LANE BUS sequences and distributes multicast and broadcast packets and handles unicast flooding.

In this release, the LES and the LANE BUS are combined and located in the same Cisco 7000 family or Cisco 4500 series router; one combined LECS and BUS is required per ELAN.

• LECS—The LECS contains the database that determines which ELAN a device belongs to (each configuration server can have a different named database). Each LANE client consults the LECS just once, when it joins an ELAN, to determine which ELAN it should join. The LECS returns the ATM address of the LES for that ELAN.

One LECS is required per LANE ATM switch cloud.

The LECS’s database can have the following four types of entries:

– ELAN name-ATM address of LES pairs

– LANE client MAC address-ELAN name pairs

– LANE client ATM template-ELAN name pairs

– Default ELAN name

Note ELAN names must be unique on an interface. If two interfaces participate in LANE, the second interface may be in a different switch cloud.

LANE Operation and CommunicationCommunication among LANE components is ordinarily handled by several types of switched virtual circuits (SVCs). Some SVCs are unidirectional; others are bidirectional. Some are point-to-point and others are point-to-multipoint. Figure 88 illustrates the various virtual channel connections (VCCs)—also known as virtual circuit connections—that are used in LANE configuration.



Figure 88 shows LANE components: LE server stands for the LANE server (LECS), LECS stands for the LANE configuration server, and BUS stands for the LANE broadcast.

Figure 88 LANE VCC Types

The following section describes various processes that occur, starting with a client requesting to join an ELAN after the component routers have been configured.

Client Joining an ELAN

The following process normally occurs after a LANE client has been enabled:

• Client requests to join an ELAN—The client sets up a connection to the LECS—a bidirectional point-to-point Configure Direct VCC—to find the ATM address of the LES for its ELAN.

LANE clients find the LECS by using the following methods in the listed order:

– Locally configured ATM address

– Interim Local Management Interface (ILMI)

– Fixed address defined by the ATM Forum

– PVC 0/17

• Configuration server identifies the LES—Using the same VCC, the LECS returns the ATM address and the name of the LES for the client’s ELAN.

• Client contacts the server for its LAN—The client sets up a connection to the LES for its ELAN (a bidirectional point-to-point Control Direct VCC) to exchange control traffic.

Once a Control Direct VCC is established between a LANE client and a LES, it remains up.

• Server verifies that the client is allowed to join the ELAN—The server for the ELAN sets up a connection to the LECS to verify that the client is allowed to join the ELAN—a bidirectional point-to-point Configure Direct (server) VCC. The server’s configuration request contains the client’s MAC address, its ATM address, and the name of the ELAN. The LECS checks its database to determine whether the client can join that LAN; then it uses the same VCC to inform the server whether the client is or is not allowed to join.

LE server

Client A

LECS

Client B

BUS

S37

36

1–72–83–11

Control direct Control distribute Configure direct (client)

4–95–106–611–12

Multicast send Multicast forward Data directConfigure direct (server)

1 2 3 4

5

6 6

2

1 3 5 4

910

911

78

7

1112



• LES allows or disallows the client to join the ELAN—If allowed, the LES adds the LANE client to the unidirectional point-to-multipoint Control Distribute VCC and confirms the join over the bidirectional point-to-point Control Direct VCC. If disallowed, the LES rejects the join over the bidirectional point-to-point Control Direct VCC.

• LANE client sends LE ARP packets for the broadcast address, which is all 1s—Sending LE ARP packets for the broadcast address sets up the VCCs to and from the BUS.

Address Resolution

As communication occurs on the ELAN, each client dynamically builds a local LANE ARP (LE ARP) table. A LE ARP table belonging to a client can also have static, preconfigured entries. The LE ARP table maps MAC addresses to ATM addresses.

Note LE ARP is not the same as IP ARP. IP ARP maps IP addresses (Layer 3) to Ethernet MAC addresses (Layer 2); LE ARP maps ELAN MAC addresses (Layer 2) to ATM addresses (also Layer 2).

When a client first joins an ELAN, its LE ARP table has no dynamic entries and the client has no information about destinations on or behind its ELAN. To learn about a destination when a packet is to be sent, the client begins the following process to find the ATM address corresponding to the known MAC address:

• The client sends a LE ARP request to the LES for this ELAN (point-to-point Control Direct VCC).

• The LES forwards the LE ARP request to all clients on the ELAN (point-to-multipoint Control Distribute VCC).

• Any client that recognizes the MAC address responds with its ATM address (point-to-point Control Direct VCC).

• The LES forwards the response (point-to-multipoint Control Distribute VCC).

• The client adds the MAC address-ATM address pair to its LE ARP cache.

• Then the client can establish a VCC to the desired destination and send packets to that ATM address (bidirectional point-to-point Data Direct VCC).

For unknown destinations, the client sends a packet to the BUS, which forwards the packet to all clients via flooding. The BUS floods the packet because the destination might be behind a bridge that has not yet learned this particular address.

Multicast Traffic

When a LANE client has broadcast or multicast traffic, or unicast traffic with an unknown address to send, the following process occurs:

• The client sends the packet to the BUS (unidirectional point-to-point Multicast Send VCC).

• The BUS forwards (floods) the packet to all clients (unidirectional point-to-multipoint Multicast Forward VCC).

This VCC branches at each ATM switch. The switch forwards such packets to multiple outputs. (The switch does not examine the MAC addresses; it simply forwards all packets it receives.)



Typical LANE ScenariosIn typical LANE cases, one or more Cisco 7000 family routers, or Cisco 4500 series routers are attached to a Cisco LightStream ATM switch. The LightStream ATM switch provides connectivity to the broader ATM network switch cloud. The routers are configured to support one or more ELANs. One of the routers is configured to perform the LECS functions. A router is configured to perform the server function and the BUS function for each ELAN. (One router can perform the server function and the BUS function for several ELANs.) In addition to these functions, each router also acts as a LANE client for one or more ELANs.

This section presents two scenarios using the same four Cisco routers and the same Cisco LightStream ATM switch. Figure 89 illustrates a scenario in which one ELAN is set up on the switch and routers. Figure 90 illustrates a scenario in which several ELANs are set up on the switch and routers.

The physical layout and the physical components of an emulated network might not differ for the single and the multiple ELAN cases. The differences are in the software configuration for the number of ELANs and the assignment of LANE components to the different physical components.

Single ELAN Scenario

In a single ELAN scenario, the LANE components might be assigned as follows:

• Router 1 includes the following LANE components:

– The LECS (one per LANE switch cloud)

– The LES and BUS for the ELAN with the default name man (for Manufacturing)

– The LANE client for the man ELAN.

• Router 2 includes a LANE client for the man ELAN.



Figure 89 illustrates this single ELAN configured across several routers.

Figure 89 Single ELAN Configured on Several Routers

Cisco LightStreamATM switch

man client

man client

man client

configuration serverman server-busman client

S50

40

Router 1

Router 2 Router 3

Router 4



Multiple ELAN Scenario

In the multiple LAN scenario, the same switch and routers are used, but multiple ELANs are configured. See Figure 90.

Figure 90 Multiple ELANs Configured on Several Routers

In the following scenario, three ELANs are configured on four routers:

• Router 1 includes following LANE components:

– The LECS (one per LANE switch cloud)

– The LES and BUS for the ELAN called man (for Manufacturing)

– The LES and BUS functions for the ELAN called eng (for Engineering)

– A LANE client for the man ELAN

– A LANE client for the eng ELAN

• Router 2 includes only the LANE clients for the man and eng ELANs.

• Router 3 includes only the LANE clients for the man and mkt (for Marketing) ELANs.

• Router 4 includes the following LANE components:

– The LES and BUS for the mkt ELAN

– A LANE client for the man ELAN

– A LANE client for the mkt ELANs

In this scenario, once routing is enabled and network level addresses are assigned, Router 1 and Router 2 can route between the man and the eng ELANs, and Router 3 and Router 4 can route between the man and the mkt ELANs.


man clientmkt client

mkt server-busman clientmkt client

man clienteng client

Configuration serverman server-buseng server-busman clienteng client

S50

39

Router 1

Router 2 Router 3

Router 4


Configuring LAN Emulation

This chapter describes how to configure LAN emulation (LANE) on the following platforms that are connected to an ATM switch or switch cloud:

• ATM Interface Processor (AIP) on the Cisco 7500 series routers

• ATM port adapter on the Cisco 7200 series and Cisco 7500 series routers

• Network Processor Module (NPM) on the Cisco 4500 and Cisco 4700 routers

Note Beginning with Cisco IOS Release 11.3, all commands supported on the Cisco 7500 series routers are also supported on the Cisco 7000 series.

This chapter contains these sections:

• LANE on ATM

• LANE Implementation Considerations

• LANE Configuration Task List

• LANE Configuration Examples


To identify the hardware platform or Cisco IOS image information associated with a feature, use the Feature Navigator on Cisco.com to search for information about the feature or refer to the Cisco IOS release notes for a specific release. For more information, see the section “Identifying Supported Platforms” in the chapter “Using Cisco IOS Software.”

LANE on ATMLANE emulates an IEEE 802.3 Ethernet or IEEE 802.5 Token Ring LAN using ATM technology. LANE provides a service interface for network-layer protocols that is identical to existing MAC layers. No changes are required to existing upper layer protocols and applications. With LANE, Ethernet and Token Ring packets are encapsulated in the appropriate ATM cells and sent across the ATM network. When the packets reach the other side of the ATM network, they are deencapsulated. LANE essentially bridges LAN traffic across ATM switches.

Configuring LAN EmulationLANE on ATM


Benefits of LANEATM is a cell-switching and multiplexing technology designed to combine the benefits of circuit switching (constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and efficiency for intermittent traffic).

LANE allows legacy Ethernet and Token Ring LAN users to take advantage of ATM’s benefits without modifying end-station hardware or software. ATM uses connection-oriented service with point-to-point signalling or multicast signalling between source and destination devices. However, LANs use connectionless service. Messages are broadcast to all devices on the network. With LANE, routers and switches emulate the connectionless service of a LAN for the endstations.

By using LANE, you can scale your networks to larger sizes while preserving your investment in LAN technology.

LANE ComponentsA single emulated LAN (ELAN) consists of the following entities: A LECS, a BUS, a LES, and LANE clients.

• LANE configuration server—A server that assigns individual clients to particular emulated LANs by directing them to the LES for the ELAN. The LANE configuration server (LECS) maintains a database of LANE client and server ATM or MAC addresses and their emulated LANs. An LECS can serve multiple emulated LANs.

• LANE broadcast and unknown server—A multicast server that floods unknown destination traffic and forwards multicast and broadcast traffic to clients within an ELAN. One broadcast and unknown server (BUS) exists per ELAN.

• LANE server—A server that provides a registration facility for clients to join the ELAN. There is one LANE server (LES) per ELAN. The LES handles LAN Emulation Address Resolution Protocol (LE ARP) requests and maintains a list of LAN destination MAC addresses. For Token Ring LANE, the LES also maintains a list of route-descriptors that is used to support source-route bridging (SRB) over the ELAN. The route-descriptors are used to determine the ATM address of the next hop in the Routing Information Field (RIF).

• LANE client—An entity in an endpoint, such as a router, that performs data forwarding, address resolution, and other control functions for a single endpoint in a single ELAN. The LANE client (LEC) provides standard LAN service to any higher layers that interface with it. A router can have multiple resident LANE clients, each connecting with different emulated LANs. The LANE client registers its MAC and ATM addresses with the LES.

ELAN entities coexist on one or more Cisco routers. On Cisco routers, the LES and the BUS are combined into a single entity.

Other LANE components include ATM switches—any ATM switch that supports the Interim Local Management Interface (ILMI) and signalling. Multiple emulated LANs can coexist on a single ATM network.

Simple Server RedundancyLANE relies on three servers: the LECS, the LES, and the BUS. If any one of these servers fails, the ELAN cannot fully function.

Configuring LAN EmulationLANE Implementation Considerations


Cisco has developed a fault tolerance mechanism known as simple server redundancy that eliminates these single points of failure. Although this scheme is proprietary, no new protocol additions have been made to the LANE subsystems.

Simple server redundancy uses multiple LECSs and multiple broadcast-and-unknown and LESs. You can configure servers as backup servers, which will become active if a master server fails. The priority levels for the servers determine which servers have precedence.

Refer to the “Configuring Fault-Tolerant Operation” section for details and notes on the Simple Server Redundancy Protocol (SSRP).

LANE Implementation ConsiderationsThe following sections contain information relevant to implementation:

• Network Support

• Hardware Support

• Addressing

• Rules for Assigning Components to Interfaces and Subinterfaces

Network SupportIn this release, Cisco supports the following networking features:

• Ethernet-emulated LANs

– Routing from one ELAN to another via IP, IPX, or AppleTalk

– Bridging between emulated LANs and between emulated LANs and other LANs

– DECnet, Banyan VINES, and XNS routed protocols

• Token-Ring emulated LANs

– IP routing (fast switched) between emulated LANs and between a Token Ring ELAN and a legacy LAN

– IPX routing between emulated LANs and between a Token Ring ELAN and a legacy LAN

– Two-port and multiport SRB (fast switched) between emulated LANs and between emulated LANs and a Token Ring

– IP and IPX multiring

– SRB, source-route translational bridging (SR/TLB), and source-route transparent bridging (SRT)

– AppleTalk for (IOS) TR-LANE and includes Appletalk fast switched routing.

– DECnet, Banyan VINES, and XNS protocols are not supported

Cisco’s implementation of LAN Emulation over 802.5 uses existing terminology and configuration options for Token Rings, including SRB. For more information about configuring SRB, see the chapter “Configuring Source-Route Bridging” in the Cisco IOS Bridging and IBM Networking Configuration Guide. Transparent bridging and Advanced Peer-to-Peer Networking (APPN) are not supported at this time.

• Hot Standby Router Protocol (HSRP)



For information about configuring APPN over Ethernet LANE, refer to the “Configuring APPN” chapter in the Cisco IOS Bridging and IBM Networking Configuration Guide.

Hardware SupportThis release of LANE is supported on the following platforms:

• Cisco 4500-M, Cisco 4700-M

• Cisco 7200 series

• Cisco 7500 series

Note Beginning with Cisco IOS Release 11.3, all commands supported on the Cisco 7500 series routers are also supported on the Cisco 7000 series routers equipped with RSP7000. Token Ring LAN emulation on Cisco 7000 series routers requires the RSP7000 upgrade. The RSP7000 upgrade requires a minimum of 24 MB DRAM and 8 MB Flash memory.

The router must contain an ATM Interface Processor (AIP), ATM port adapter, or an NP-1A ATM Network Processor Module (NPM). These modules provide an ATM network interface for the routers. Network interfaces reside on modular interface processors, which provide a direct connection between the high-speed Cisco Extended Bus (CxBus) and the external networks. The maximum number of AIPs, ATM port adapters, or NPMs that the router supports depends on the bandwidth configured. The total bandwidth through all the AIPs, ATM port adapters, or NPMs in the system should be limited to 200 Mbps full duplex—two Transparent Asynchronous Transmitter/Receiver Interfaces (TAXIs), one Synchronous Optical Network (SONET) and one E3, or one SONET and one lightly used SONET.

This feature also requires one of the following switches:

• Cisco LightStream 1010 (recommended)

• Cisco LightStream 100

• Any ATM switch with UNI 3.0/3.1 and ILMI support for communicating the LECS address

TR-LANE requires Cisco IOS Release 3.1(2) or later on the LightStream 100 switch and Cisco IOS Release 11.1(8) or later on the LightStream 1010.

For a complete description of the routers, switches, and interfaces, refer to your hardware documentation.

AddressingOn a LAN, packets are addressed by the MAC-layer address of the destination and source stations. To provide similar functionality for LANE, MAC-layer addressing must be supported. Every LANE client must have a MAC address. In addition, every LANE component (server, client, BUS, and LECS) must have an ATM address that is different from that of all the other components.

All LANE clients on the same interface have the same, automatically assigned MAC address. That MAC address is also used as the end-system identifier (ESI) part of the ATM address, as explained in the next section. Although client MAC addresses are not unique, all ATM addresses are unique.



LANE ATM Addresses

A LANE ATM address has the same syntax as an NSAP, but it is not a network-level address. It consists of the following:

• A 13-byte prefix that includes the following fields defined by the ATM Forum:

– AFI (Authority and Format Identifier) field (1 byte)

– DCC (Data Country Code) or ICD (International Code Designator) field (2 bytes)

– DFI field (Domain Specific Part Format Identifier) (1 byte)

– Administrative Authority field (3 bytes)

– Reserved field (2 bytes)

– Routing Domain field (2 bytes)

– Area field (2 bytes)

• A 6-byte end-system identifier (ESI)

• A 1-byte selector field

Method of Automatically Assigning ATM Addresses

We provide the following standard method of constructing and assigning ATM and MAC addresses for use in a LECS’s database. A pool of MAC addresses is assigned to each ATM interface on the router. On the Cisco 7200 series routers, Cisco 7500 series routers, Cisco 4500 routers, and Cisco 4700 routers, the pool contains eight MAC addresses. For constructing ATM addresses, the following assignments are made to the LANE components:

• The prefix fields are the same for all LANE components in the router; the prefix indicates the identity of the switch. The prefix value must be configured on the switch.

• The ESI field value assigned to every client on the interface is the first of the pool of MAC addresses assigned to the interface.

• The ESI field value assigned to every server on the interface is the second of the pool of MAC addresses.

• The ESI field value assigned to the broadcast-and-unknown server on the interface is the third of the pool of MAC addresses.

• The ESI field value assigned to the configuration server is the fourth of the pool of MAC addresses.

• The selector field value is set to the subinterface number of the LANE component—except for the LECS, which has a selector field value of 0.

Because the LANE components are defined on different subinterfaces of an ATM interface, the value of the selector field in an ATM address is different for each component. The result is a unique ATM address for each LANE component, even within the same router. For more information about assigning components to subinterfaces, see the “Rules for Assigning Components to Interfaces and Subinterfaces” section later in this chapter.

For example, if the MAC addresses assigned to an interface are 0800.200C.1000 through 0800.200C.1007, the ESI part of the ATM addresses is assigned to LANE components as follows:

• Any client gets the ESI 0800.200c.1000.

• Any server gets the ESI 0800.200c.1001.



• The BUS gets the ESI 0800.200c.1002.

• The LECS gets the ESI 0800.200c.1003.

Refer to the “Multiple Token Ring ELANs with Unrestricted Membership Example” and the “Multiple Token Ring ELANs with Restricted Membership Example” sections for examples using MAC address values as ESI field values in ATM addresses and for examples using subinterface numbers as selector field values in ATM addresses.

Using ATM Address Templates

ATM address templates can be used in many LANE commands that assign ATM addresses to LANE components (thus overriding automatically assigned ATM addresses) or that link client ATM addresses to emulated LANs. The use of templates can greatly simplify the use of these commands. The syntax of address templates, the use of address templates, and the use of wildcard characters within an address template for LANE are very similar to those for address templates of ISO CLNS.

Note E.164-format ATM addresses do not support the use of LANE ATM address templates.

LANE ATM address templates can use two types of wildcards: an asterisk (*) to match any single character, and an ellipsis (...) to match any number of leading or trailing characters.

In LANE, a prefix template explicitly matches the prefix but uses wildcards for the ESI and selector fields. An ESI template explicitly matches the ESI field but uses wildcards for the prefix and selector. Table 43 indicates how the values of unspecified digits are determined when an ATM address template is used:

Table 43 Values of Unspecified Digits in ATM Address Templates

Unspecified Digits In Value Is

Prefix (first 13 bytes) Obtained from ATM switch via Interim Local Management Interface (ILMI)

ESI (next 6 bytes) Filled with the slot MAC address1 plus

• 0—LANE client

• 1—LES

• 2—LANE BUS

• 3—LECS

1. The lowest of the pool of MAC addresses assigned to the ATM interface plus a value that indicates the LANE component. For the Cisco 7200 series routers, Cisco 7500 series routers, Cisco 4500 routers, and Cisco 4700 routers, the pool has eight MAC addresses.

Selector field (last 1 byte) Subinterface number, in the range 0 through 255.

Configuring LAN EmulationLANE Configuration Task List


Rules for Assigning Components to Interfaces and SubinterfacesThe following rules apply to assigning LANE components to the major ATM interface and its subinterfaces in a given router:

• The LECS always runs on the major interface.

The assignment of any other component to the major interface is identical to assigning that component to the 0 subinterface.

• The server and the client of the same ELAN can be configured on the same subinterface in a router.

• Clients of two different emulated LANs cannot be configured on the same subinterface in a router.

• Servers of two different emulated LANs cannot be configured on the same subinterface in a router.

LANE Configuration Task ListBefore you begin to configure LANE, you must decide whether you want to set up one or multiple emulated LANs. If you set up multiple emulated LANs, you must also decide where the servers and clients will be located, and whether to restrict the clients that can belong to each ELAN. Bridged emulated LANs are configured just like any other LAN, in terms of commands and outputs. Once you have made those basic decisions, you can proceed to configure LANE.

To configure LANE, perform the tasks described in the following sections:

• Creating a LANE Plan and Worksheet

• Configuring the Prefix on the Switch

• Setting Up the Signalling and ILMI PVCs

• Displaying LANE Default Addresses

• Entering the LECS’s ATM Address on the Cisco Switch

• Setting Up the LECS’s Database

• Enabling the LECS

• Setting Up LESs and Clients

Once LANE is configured, you can configure Multiprotocol over ATM (MPOA). For MPOA to work with LANE, a LANE client must have an ELAN ID to work properly, a LANE client must have an ELAN ID. To set up a LANE client for MPOA and give an ELAN ID perform the tasks described in the following section:

• Setting Up LANE Clients for MPOA

Although the sections described contain information about configuring SSRP fault tolerance, refer to the “Configuring Fault-Tolerant Operation” section for detailed information about requirements and implementation considerations.

Once LANE is configured, you can monitor and maintain the components in the participating routers by completing the tasks described in the “Monitoring and Maintaining the LANE Components” section.

For configuration examples, see the “LANE Configuration Examples” section at the end of this chapter.



Creating a LANE Plan and WorksheetDraw up a plan and a worksheet for your own LANE scenario, showing the following information and leaving space for noting the ATM address of each of the LANE components on each subinterface of each participating router:

• The router and interface where the LECS will be located.

• The router, interface, and subinterface where the LES and BUS for each ELAN will be located. There can be multiple servers for each ELAN for fault-tolerant operation.

• The routers, interfaces, and subinterfaces where the clients for each ELAN will be located.

• The name of the default ELAN (optional).

• The names of the emulated LANs that will have unrestricted membership.

• The names of the emulated LANs that will have restricted membership.

The last three items in this list are very important; they determine how you set up each ELAN in the LECS’s database.

Configuring the Prefix on the SwitchBefore you configure LANE components on any Cisco 7200 series router, Cisco 7500 series router, Cisco 4500 router, or Cisco 4700 router, you must configure the Cisco ATM switch with the ATM address prefix to be used by all LANE components in the switch cloud. On the Cisco switch, the ATM address prefix is called the node ID. Prefixes must be 26 digits long. If you provide fewer than 26 digits, zeros are added to the right of the specified value to fill it to 26 digits.

To set the ATM address prefix on the Cisco LightStream 1010 Switch, use the following commands on the switch beginning in global configuration mode:

To set the ATM address prefix on the Cisco LightStream 100, use the following commands on the Cisco switch:

On the switches, you can display the current prefix by using the show network EXEC command.

Note If you do not save the configured value permanently, it will be lost when the switch is reset or powered off.

Command Purpose

Step 1 Router(config)# atm-address {atm-address | prefix...}

Sets the local node ID (prefix of the ATM address).

Step 2 Router(config)# exit Exits global configuration mode.

Step 3 Router# copy system:running-config nvram:startup-config

Saves the configuration values permanently.

Command Purpose

Step 1 Router(config-route-map)# set local name ip-address mask prefix


Step 2 Router(config-route-map)# save Saves the configuration values permanently.



Setting Up the Signalling and ILMI PVCsYou must set up the signalling permanent virtual circuit (PVC) and the PVC that will communicate with the ILMI on the major ATM interface of any router that participates in LANE.

Complete this task only once for a major interface. You do not need to repeat this task on the same interface even though you might configure LESs and clients on several of its subinterfaces.

To set up these PVCs, use the following commands beginning in global configuration mode:

Displaying LANE Default AddressesYou can display the LANE default addresses to make configuration easier. Complete this task for each router that participates in LANE. This command displays default addresses for all ATM interfaces present on the router. Write down the displayed addresses on your worksheet.

To display the default LANE addresses, use the following command in EXEC mode:

Entering the LECS’s ATM Address on the Cisco Switch You must enter the LECS’s ATM address into the Cisco LightStream 100 or Cisco Lightstream 1010 ATM switch and save it permanently so that the value is not lost when the switch is reset or powered off.

You must specify the full 40-digit ATM address. Use the addresses on your worksheet that you obtained from the previous task.

If you are configuring SSRP or Fast Simple Server Redundancy Protocol (FSSRP), enter the multiple LECS addresses into the end ATM switches. The switches are used as central locations for the list of LECS addresses. LANE components connected to the switches obtain the global list of LECS addresses from the switches.

Command Purpose

Step 1

Router(config-if)# interface atm slot/0

Router(config-if)# interface atm slot/port-adapter/0

Router(config-if)# interface atm number

Specifies the major ATM interface and enter interface configuration mode:

• On the AIP for Cisco 7500 series routers; on the ATM port adapter for Cisco 7200 series routers.

• On the ATM port adapter for Cisco 7500 series routers.

• On the NPM for Cisco 4500 and Cisco 4700 routers.

Step 2 Router(config-if)# atm pvc vcd vpi vci qsaal

Sets up the signalling PVC that sets up and tears down switched virtual circuits (SVCs); the vpi and vci values are usually set to 0 and 5, respectively.

Step 3 Router(config-if)# atm pvc vcd vpi vci ilmi

Sets up a PVC to communicate with the ILMI; the vpi and vci values are usually set to 0 and 16, respectively.

Command PurposeRouter# show lane default-atm-addresses Displays the LANE default addresses.



Depending on which type of switch you are using, perform one of the tasks in the following sections:

• Entering the ATM Addresses on the Cisco LightStream 1010 ATM Switch

• Entering the ATM Addresses on the Cisco LightStream 100 ATM Switch

Entering the ATM Addresses on the Cisco LightStream 1010 ATM Switch

On the Cisco LightStream 1010 ATM switch, the LECS address can be specified for a port or for the entire switch.

To enter the LECS addresses on the Cisco LightStream 1010 ATM switch for the entire switch, use the following commands beginning in global configuration mode:

To enter the LECS addresses on the Cisco LightStream 1010 ATM switch per port, use the following commands beginning in interface configuration mode:

Entering the ATM Addresses on the Cisco LightStream 100 ATM Switch

To enter the LECS’s ATM address into the Cisco LightStream 100 ATM switch and save it permanently, use the following commands in privileged EXEC mode:

Command Purpose

Step 1 Router(config)# atm lecs-address-default lecsaddress [sequence #]1

1.Refer to the LightStream 1010 ATM Switch Command Reference for further information about this command.

Specifies the LECS’s ATM address for the entire switch. If you are configuring SSRP, include the ATM addresses of all the LECSs.



Saves the configuration value permanently.

Command Purpose

Step 1 Router(config-if)# atm lecs-address lecsaddress [sequence #]1

1.Refer to the LightStream 1010 ATM Switch Command Reference for further information about this command.

Specifies the LECS’s ATM address for a port. If you are configuring SSRP, include the ATM addresses of all the LECSs.

Step 2 Router(config-if)# Ctrl-Z Exits interface configuration mode.


Saves the configuration value permanently.

Command Purpose

Step 1 Router# set configserver index atm-address Specifies the LECS’s ATM address. If you are configuring SSRP, repeat this command for each LECS address. The index value determines the priority. The highest priority is 0. There can be a maximum of 4 LECSs.

Step 2 Router# save Saves the configuration value permanently.



Setting Up the LECS’s DatabaseThe LECS’s database contains information about each ELAN, including the ATM addresses of the LESs.

You can specify one default ELAN in the database. The LECS will assign any client that does not request a specific ELAN to the default ELAN.

Emulated LANs are either restricted or unrestricted. The LECS will assign a client to an unrestricted ELAN if the client specifies that particular ELAN in its configuration. However, the LECS will only assign a client to a restricted ELAN if the client is specified in the database of the LECS as belonging to that ELAN. The default ELAN must have unrestricted membership.

If you are configuring fault tolerance, you can have any number of servers per ELAN. Priority is determined by entry order; the first entry has the highest priority, unless you override it with the index option.

To set up the database, complete the tasks in the following sections as appropriate for your ELAN plan and scenario:

• Setting Up the Database for the Default ELAN Only

• Setting Up the Database for Unrestricted-Membership Emulated LANs

• Setting Up the Database for Restricted-Membership LANs

Setting Up the Database for the Default ELAN Only

When you configure a router as the LECS for one default ELAN, you provide a name for the database, the ATM address of the LES for the ELAN, and a default name for the ELAN. In addition, you indicate that the LECS’s ATM address is to be computed automatically.

When you configure a database with only a default unrestricted ELAN, you do not have to specify where the LANE clients are located. That is, when you set up the LECS’s database for a single default ELAN, you do not have to provide any database entries that link the ATM addresses of any clients with the ELAN name. All of the clients will be assigned to the default ELAN.

To set up the LECS for the default ELAN, use the following commands beginning in global configuration mode:

Command Purpose

Step 1 Router(config)# lane database database-name Creates a named database for the LECS.

Step 2 Router(lane-config-dat)# name elan-name server-atm-address atm-address [index number]

In the configuration database, binds the name of the ELAN to the ATM address of the LES.

If you are configuring SSRP, repeat this step for each additional server for the same ELAN. The index determines the priority. The highest priority is 0.

Step 3 Router(lane-config-dat)# name elan-name local-seg-id segment-number

If you are configuring a Token Ring ELAN, assigns a segment number to the emulated Token Ring LAN in the configuration database.

Step 4 Router(lane-config-dat)# default-name elan-name

In the configuration database, provides a default name for the ELAN.

Step 5 Router(lane-config-dat)# exit Exits from database configuration mode and return to global configuration mode.



In Step 2, enter the ATM address of the server for the specified ELAN, as noted in your worksheet and obtained in the “Displaying LANE Default Addresses” section.

You can have any number of servers per ELAN for fault tolerance. Priority is determined by entry order. The first entry has the highest priority unless you override it with the index option.

If you are setting up only a default ELAN, the elan-name value in Steps 2 and 3 is the same as the default ELAN name you provide in Step 4.

To set up fault-tolerant operation, see the “Configuring Fault-Tolerant Operation” section later in this chapter.

Setting Up the Database for Unrestricted-Membership Emulated LANs

When you set up a database for unrestricted emulated LANs, you create database entries that link the name of each ELAN to the ATM address of its server.

However, you may choose not to specify where the LANE clients are located. That is, when you set up the LECS’s database, you do not have to provide any database entries that link the ATM addresses or MAC addresses of any clients with the ELAN name. The LECS will assign the clients to the emulated LANs specified in the client’s configurations.

To configure a router as the LECS for multiple emulated LANs with unrestricted membership, use the following commands beginning in global configuration mode:

Command Purpose


Step 2 Router(lane-config-dat)# name elan-name1 server-atm-address atm-address [index number]

In the configuration database, binds the name of the first ELAN to the ATM address of the LES for that ELAN.

If you are configuring SSRP, repeat this step with the same ELAN name but with different server ATM addresses for each additional server for the same ELAN. The index determines the priority. The highest priority is 0.

Step 3 Router(lane-config-dat)# name elan-name2 server-atm-address atm-address [index number]

In the configuration database, binds the name of the second ELAN to the ATM address of the LES.


Repeat this step, providing a different ELAN name and ATM address for each additional ELAN in this switch cloud.

Step 4 Router(lane-config-dat)# name elan-name1 local-seg-id segment-number

For a Token Ring ELAN, assigns a segment number to the first emulated Token Ring LAN in the configuration database.


For Token Ring emulated LANs, assigns a segment number to the second emulated Token Ring LAN in the configuration database.

Repeat this step, providing a different ELAN name and segment number for each additional source-route bridged ELAN in this switch cloud.



In the preceding steps, enter the ATM address of the server for the specified ELAN, as noted in your worksheet and obtained in the “Displaying LANE Default Addresses” section.


Setting Up the Database for Restricted-Membership LANs

When you set up the database for restricted-membership emulated LANs, you create database entries that link the name of each ELAN to the ATM address of its server.

However, you must also specify where the LANE clients are located. That is, for each restricted-membership ELAN, you provide a database entry that explicitly links the ATM address or MAC address of each client of that ELAN with the name of that ELAN.

The client database entries specify which clients are allowed to join the ELAN. When a client requests to join an ELAN, the LECS consults its database and then assigns the client to the ELAN specified in the LECS’s database.

When clients for the same restricted-membership ELAN are located in multiple routers, each client’s ATM address or MAC address must be linked explicitly with the name of the ELAN. As a result, you must configure as many client entries (at Steps 6 and 7, in the following procedure) as you have clients for emulated LANs in all the routers. Each client will have a different ATM address in the database entries.

To set up the LECS for emulated LANs with restricted membership, use the following commands beginning in global configuration mode:

Step 6 Router(lane-config-dat)# default-name elan-name1

(Optional) Specifies a default ELAN for LANE clients not explicitly bound to an ELAN.


Command Purpose

Command Purpose


Step 2 Router(lane-config-dat)# name elan-name1 server-atm-address atm-address restricted [index number]

In the configuration database, binds the name of the first ELAN to the ATM address of the LES for that ELAN.


Step 3 Router(lane-config-dat)# name elan-name2 server-atm-address atm-address restricted [index number]

In the configuration database, binds the name of the second ELAN to the ATM address of the LES.


Repeat this step, providing a different name and a different ATM address, for each additional ELAN.




Enabling the LECSOnce you have created the database, you can enable the LECS on the selected ATM interface and router by using the following commands beginning in global configuration mode:


For a Token Ring ELAN, assigns a segment number to the first emulated Token Ring LAN in the configuration database.


If you are configuring Token Ring emulated LANs, assigns a segment number to the second emulated Token Ring LAN in the configuration database.


Step 6 Router(lane-config-dat)# client-atm-address atm-address-template name elan-name1

Adds a database entry associating a specific client’s ATM address with the first restricted-membership ELAN.

Repeat this step for each of the clients of the first restricted-membership ELAN.

Step 7 Router(lane-config-dat)# client-atm-address atm-address-template name elan-name2

Adds a database entry associating a specific client’s ATM address with the second restricted-membership ELAN.

Repeat this step for each of the clients of the second restricted-membership ELAN.

Repeat this step, providing a different name and a different list of client ATM address, for each additional ELAN.


Command Purpose

Command Purpose

Step 1

Router(config)# interface atm slot/0[.subinterface-number]

Router(config)# interface atm slot/port-adapter/0[.subinterface-number]

Router(config)# interface atm number[.subinterface-number]

If you are not currently configuring the interface, specifies the major ATM interface where the LECS is located.

• On the AIP for Cisco 7500 series routers; On the ATM port adapter for Cisco 7200 series routers.



Step 2 Router(config-if)# lane config database database-name

Link the LECS’s database name to the specified major interface, and enable the LECS.



Setting Up LESs and ClientsFor each router that will participate in LANE, set up the necessary servers and clients for each ELAN; then display and record the server and client ATM addresses. Be sure to keep track of the router interface where the LECS will eventually be located.

You can set up servers for more than one ELAN on different subinterfaces or on the same interface of a router, or you can place the servers on different routers.

When you set up a server and BUS on a router, you can combine them with a client on the same subinterface, a client on a different subinterface, or no client at all on the router.

Where you put the clients is important because any router with clients for multiple emulated LANs can route frames between those emulated LANs.

Depending on where your clients and servers are located, perform one of the following tasks for each LANE subinterface.

• Setting Up the Server, BUS, and a Client on a Subinterface

• Setting Up Only a Client on a Subinterface

Step 3Router(config-if)# lane config auto-config-atm-address

Router(config-if)# lane config auto-config-atm-addressorRouter(config-if)# lane config fixed-config-atm-address

Router(config-if)# lane config fixed-config-atm-address

Router(config-if)# lane config config-atm-address atm-address-template

Specifies how the LECS’s ATM address will be computed. You may opt to choose one of the following scenarios:

The LECS will participate in SSRP and the address is computed by the automatic method.

The LECS will participate in SSRP, and the address is computed by the automatic method. If the LECS is the master, the fixed address is also used.

The LECS will not participate in SSRP, the LECS is the master, and only the well-known address is used.

The LECS will participate in SSRP and the address is computed using an explicit, 20-byte ATM address.

Step 4 exit Exits interface configuration mode.

Step 5 Ctrl-Z Returns to EXEC mode.

Step 6 copy system:running-config nvram:startup-config

Saves the configuration.

Command Purpose



Setting Up the Server, BUS, and a Client on a Subinterface

To set up the server, BUS, and (optionally) clients for an ELAN, use the following commands beginning in global configuration mode:

If the ELAN in Step 3 is intended to have restricted membership, consider carefully whether you want to specify its name here. You will specify the name in the LECS’s database when it is set up. However, if you link the client to an ELAN in this step, and through some mistake it does not match the database entry linking the client to an ELAN, this client will not be allowed to join this ELAN or any other.

If you do decide to include the name of the ELAN linked to the client in Step 3 and later want to associate that client with a different ELAN, make the change in the LECS’s database before you make the change for the client on this subinterface.

Each ELAN is a separate subnetwork. In Step 4 make sure that the clients of the same ELAN are assigned protocol addresses on the same subnetwork and that clients of different emulated LANs are assigned protocol addresses on different subnetworks.

Setting Up Only a Client on a Subinterface

On any given router, you can set up one client for one ELAN or multiple clients for multiple emulated LANs. You can set up a client for a given ELAN on any routers you choose to participate in that ELAN. Any router with clients for multiple emulated LANs can route packets between those emulated LANs.

You must first set up the signalling and ILMI PVCs on the major ATM interface, as described earlier in the “Setting Up the Signalling and ILMI PVCs” section, before you set up the client.

Command Purpose

Step 1

Router(config)# interface atm slot/0.subinterface-number

Router(config)# interface atm slot/port-adapter/0.subinterface-number

Router(config)# interface atm number.subinterface-number

Specifies the subinterface for the ELAN on this router.




Step 2 Router(config-if)# lane server-bus {ethernet | tokenring} elan-name

Enables a LES and a LANE BUS for the ELAN.

Step 3 Router(config-if)# lane client {ethernet | tokenring} [elan-name] [elan-id id]

(Optional) Enables a LANE client for the ELAN.

To participate in MPOA, configures the LES and a LANE BUS for the ELAN with the ELAN ID.

Step 4 Router(config-if)# ip address mask1

1. The command or commands depend on the routing protocol used. If you are using IPX or AppleTalk, see the relevant protocol chapter (IPX or AppleTalk) in the Cisco IOS AppleTalk and Novell IPX Configuration Guide for the commands to use.

Provides a protocol address for the client.

Step 5 Router(config-if)# Ctrl-Z Returns to EXEC mode.





To set up only a client for an emulated LANs, use the following commands beginning in interface configuration mode:

Each ELAN is a separate subnetwork. In Step 2, make sure that the clients of the same ELAN are assigned protocol addresses on the same subnetwork and that clients of different emulated LANs are assigned protocol addresses on different subnetworks.

Disabling the LE_FLUSH Process of LAN Emulation Clients

Disable the LE_FLUSH process and make the transition from using the BUS to using a data direct virtual channel connection (VCC). Disabling the LE_FLUSH process is recommended to prevent the initial packet drops during the establishment of LANE Direct VC. With the LE_FLUSH process disabled, LAN Emulation Clients (LECs) in the node will not send a flush request and will directly use a data direct VCC for data transfer.

Note Disabling the LE_FLUSH process affects all the LECs in a Cisco networking device.

To keep LECs from sending LE_FLUSH messages to the remote LEC, use the following command in interface configuration mode:

Command Purpose

Step 1

Router(config)# interface atm slot/0.subinterface-number

Router(config)# interface atm slot/port-adapter/0.subinterface-number

Router(config)# interface atm number.subinterface-number

Specifies the subinterface for the ELAN on this router.




Step 2 Router(config-if)# ip address mask1

1. The command or commands depend on the routing protocol used. If you are using IPX or AppleTalk, see the relevant protocol chapter (IPX or AppleTalk) in the Cisco IOS AppleTalk and Novell IPX Configuration Guide for the commands to use.

Provides a protocol address for the client on this subinterface.

Step 3 Router(config-if)# lane client {ethernet | tokenring} [elan-name]

Enables a LANE client for the ELAN.

Step 4 Router(config-if)# Ctrl-Z Returns to EXEC mode.



Command PurposeRouter(config-if)# no lane client flush Disables the flush mechanism of a LEC.



Setting Up LANE Clients for MPOAFor Multiprotocol over ATM (MPOA) to work properly, a LANE client must have an ELAN ID for all ELANs represented by the LANE client. To configure an ELAN ID, use one of the following commands in LANE database configuration mode or in interface configuration mode when starting up the LES for that ELAN:

Caution If an ELAN ID is supplied by both commands, make sure that the ELAN ID matches in both.

For more information on configuring the MPOA client, refer to the “Configuring the Multiprotocol over ATM Client” chapter.

Configuring Fault-Tolerant OperationThe LANE simple server redundancy feature creates fault tolerance using standard LANE protocols and mechanisms. If a failure occurs on the LECS or on the LES/BUS, the ELAN can continue to operate using the services of a backup LES. This protocol is called the SSRP.

This section describes how to configure simple server redundancy for fault tolerance on an ELAN.

Note This server redundancy does not overcome other points of failure beyond the router ports: Additional redundancy on the LAN side or in the ATM switch cloud are not a part of the LANE simple server redundancy feature.

Simple Server Redundancy Requirements

For simple LANE service replication or fault tolerance to work, the ATM switch must support multiple LES addresses. This mechanism is specified in the LANE standard. The LE servers establish and maintain a standard control circuit that enables the server redundancy to operate.

LANE simple server redundancy is supported on Cisco IOS Release 11.2 and later. Older LANE configuration files continue to work with this new software.

This redundancy feature works only with Cisco LECSs and LES/BUS combinations. Third-party LANE Clients can be used with the SSRP, but third-party configuration servers, LE servers, and BUS do not support SSRP.

Command PurposeRouter(lane-config-dat)# name elan-name elan-id id Configures the ELAN ID in the LAN Emulation Client Server

(LECS) database to participate in MPOA.

Router(lane-config-dat)# lane server-bus {ethernet | tokenring} elan-name [elan-id id]

Configures the LES and a LANE BUS for the ELAN (ELAN).

To participate in MPOA, configure the LES and a LANE BUS for the ELAN with the ELAN ID.



For server redundancy to work correctly:

• All the ATM switches must have identical lists of the global LECS addresses, in the identical priority order.

• The operating LECSs must use exactly the same configuration database. Load the configuration table data using the copy {rcp | tftp} system:running-config command. This method minimizes errors and enables the database to be maintained centrally in one place.

The LANE protocol does not specify where any of the ELAN server entities should be located, but for the purpose of reliability and performance, Cisco implements these server components on its routers.

Fast Simple Server Redundancy Requirements

Fast Simple Server Replication Protocol (FSSRP) differs from LANE SSRP in that all configured LE servers of an ELAN are always active. FSSRP-enabled LANE clients have virtual circuits (VCs) established to a maximum of four LE servers and broadcast and unknown servers (BUSs) at one time. If a single LES goes down, the LANE client quickly switches over to the next LES and BUS resulting in no data or LE-ARP table entry loss and no extraneous signalling.

Due to the increase in LAN client connections to all LE servers in an ELAN, FSSRP increases the number of VCs in your network. On a per client basis, up to 12 additional VCs will be added. These include the additional control direct, control distribute, multicast send and multicast forward VCs (times the 3 extra LE servers and BUSs), which totals 12 additional VCs.

Users should take care to calculate whether or not the number of existing VCs in their network can be maintained with additional VC connections to the secondary LE servers and BUSs.

A LANE client may connect to up to only 4 LE servers and BUSs at a time.

Redundant Configuration Servers

To enable redundant LECSs, enter the multiple LECS addresses into the end ATM switches. LANE components can obtain the list of LECS addresses from the ATM switches through the Interim Local Management Interface (ILMI).

Refer to the “Entering the LECS’s ATM Address on the Cisco Switch” section for more details.

Redundant Servers and BUSs

The LECS turns on server/BUS redundancy by adjusting its database to accommodate multiple server ATM addresses for a particular ELAN. The additional servers serve as backup servers for that ELAN.

To activate the feature, you add an entry for the hierarchical list of servers that will support the given ELAN. All database modifications for the ELAN must be identical on all LECSs.

Refer to the “Setting Up the LECS’s Database” section for more details.

Implementation Considerations

The following is a list of LANE implementation restrictions:

• The LightStream 1010 can handle up to 16 LECS addresses. The LightStream 100 allows a maximum of 4 LECS addresses.

• There is no limit on the number of LE servers that can be defined per ELAN.

• When a LECS switchover occurs, no previously joined clients are affected.



• When a LES/BUS switches over, momentary loss of clients occurs until they are all transferred to the new LES/BUS.

• LECSs come up as masters until a higher-level LECS tells them otherwise. This is automatic and cannot be changed.

• If a higher-priority LES comes online, it bumps the current LES off on the same ELAN. Therefore, there may be some flapping of clients from one LES to another after a powerup, depending on the order of the LE servers coming up. Flapping should settle after the last highest-priority LES comes up.

• If none of the specified LE servers are up or connected to the master LECS and more than one LES is defined for an ELAN, a configuration request for that specific ELAN is rejected by the LECS.

• Changes made to the list of LECS addresses on ATM switches may take up to a minute to propagate through the network. Changes made to the configuration database regarding LES addresses take effect almost immediately.

• If none of the designated LECSs is operational or reachable, the ATM Forum-defined well-known LECS address is used.

• You can override the LECS address on any subinterface, by using the following commands:

– lane auto-config-atm-address

– lane fixed-config-atm-address

– lane config-atm-address

Caution When an override like this is performed, fault-tolerant operation cannot be guaranteed. To avoid affecting the fault-tolerant operation, do not override any LECS, LES or BUS addresses.

• If an underlying ATM network failure occurs, there may be multiple master LECSs and multiple active LE servers for the same ELAN. This situation creates a “partitioned” network. The clients continue to operate normally, but transmission between different partitions of the network is not possible. When the network break is repaired, the system recovers.

• When the LECS is already up and running, and you use the lane config fixed-config-atm-address interface command to configure the well-known LECS address, be aware of the following scenarios:

– If you configure the LECS with only the well-known address, the LECS will not participate in the SSRP, act as a “standalone” master, and only listen on the well-known LECS address. This scenario is ideal if you want a “standalone” LECS that does not participate in SSRP, and you would like to listen to only the well-known address.

– If only the well-known address is already assigned, and you assign at least one other address to the LECS, (additional addresses are assigned using the lane config auto-config-atm-address interface command and/or the lane config config-atm-address interface command) the LECS will participate in the SSRP and act as the master or slave based on the normal SSRP rules. This scenario is ideal if you would like the LECS to participate in SSRP, and you would like to make the master LECS listen on the well-known address.

– If the LECS is participating in SSRP, has more than one address (one of which is the well-known address), and all the addresses but the well-known address is removed, the LECS will declare itself the master and stop participating in SSRP completely.

– If the LECS is operating as an SSRP slave, and it has the well-known address configured, it will not listen on the well-known address unless it becomes the master.

– If you want the LECS to assume the well-known address only when it becomes the master, configure the LECS with the well-known address and at least one other address.



SSRP Changes to Reduce Network Flap

SSRP was originally designed so that when a higher LES came on line, all the LECs in that ELAN flipped over to the higher LES. This caused unnecessary disruptions in large networks. Now SSRP is designed to eliminate unnecessary flapping. If the current LES is healthy, the flapping can be eliminated by changing the SSRP behavior so that the ELAN does not flip over to another LES. Obviously, if the currently active LES goes down, all the LECs will then be switched over to the first available highest LES in the list. This is now the default behavior.

If ELANs are now configured in the new way, an LECS switchover may or may not cause a network flap depending on how quickly each LES now reconnects to the new master LECS. If the old active LES connects first, the flap will not occur. However, if another LES connects first (since now the criteria is that the first connected LES is assumed the master LES, rather than the highest ranking one), then the network will still flap.

For customers who would specifically like to maintain the old SSRP behavior, they can use the new LECS name elan-name preempt LANE database configuration command. This command will force the old behavior to be maintained. This feature can be enabled/disabled on a per individual ELAN basis from the LECS database. In the older scheme (preempt), the LES switchover caused network flap.

To enable network flap and set the ELAN preempt for a LES, use the following command in LANE database configuration mode:

Command PurposeRouter(lane-config-dat)# name elan-name preempt Sets the ELAN LES preemption.



Monitoring and Maintaining the LANE ComponentsAfter configuring LANE components on an interface or any of its subinterfaces, on a specified subinterface, or on an ELAN, you can display their status. To show LANE information, use the following commands in EXEC mode:

Command Purpose

|Router# show lane [interface atm slot/0[.subinterface-number] | name elan-name] [brief]

Router# show lane [interface atm slot/port-adapter/0[.subinterface-number] | name elan-name] [brief]

Router# show lane [interface atm number[.subinterface-number] | name elan-name] [brief]

Displays the global and per-virtual channel connection LANE information for all the LANE components and emulated LANs configured on an interface or any of its subinterfaces.




Router# show lane bus [interface atm slot/0[.subinterface-number] | name elan-name] [brief]

Router# show lane bus [interface atm slot/port-adapter/ 0 [.subinterface-number] | name elan-name] [brief]

Router# show lane bus [interface atm number[.subinterface-number] | name elan-name] [brief]

Displays the global and per-VCC LANE information for the BUS configured on any subinterface or ELAN.




Router# show lane client [interface atm slot/0[.subinterface-number] | name elan-name] [brief]

Router# show lane client [interface atm slot/port-adapter/0[.subinterface-number] | name elan-name] [brief]

Router# show lane client [interface atm number[.subinterface-number] | name elan-name] [brief]

Displays the global and per-VCC LANE information for all LANE clients configured on any subinterface or ELAN.






Router# show lane config [interface atm slot/0]

Router# show lane config [interface atm slot/port-adapter/0]

Router# show lane config [interface atm number]

Displays the global and per-VCC LANE information for the LECS configured on any interface.




Router# show lane database [database-name] Displays the LECS’s database.

Router# show lane default-atm-addresses [interface atm slot/0.subinterface-number]

Router# show lane default-atm-addresses [interface atm slot/port-adapter/0.subinterface-number]

Router# show lane default-atm-addresses [interface atm number.subinterface-number]

Displays the automatically assigned ATM address of each LANE component in a router or on a specified interface or subinterface.




Router# show lane le-arp [interface atm slot/0[.subinterface-number] | name elan-name]

Router# show lane le-arp [interface atm slot/port-adapter/0[.subinterface-number] | name elan-name]

Router# show lane le-arp [interface atm number[.subinterface-number] | name elan-name]

Display the LANE ARP table of the LANE client configured on the specified subinterface or ELAN.




Router# show lane server [interface atm slot/0[.subinterface-number] | name elan-name] [brief]

Router# show lane server [interface atm slot/port-adapter/0[.subinterface-number] | name elan-name] [brief]

Router# show lane server [interface atm number[.subinterface-number] | name elan-name] [brief]

Display the global and per-VCC LANE information for the LES configured on a specified subinterface or ELAN.




Command Purpose

Configuring LAN EmulationLANE Configuration Examples


LANE Configuration ExamplesThe examples in the following sections describe how to configure LANE for the following cases:

• Default Configuration for a Single Ethernet ELAN Example

• Default Configuration for a Single Ethernet ELAN with a Backup LECS and LES Example

• Multiple Token Ring ELANs with Unrestricted Membership Example

• Multiple Token Ring ELANs with Restricted Membership Example

• TR-LANE with 2-Port SRB Example

• TR-LANE with Multiport SRB Example

• Routing Between Token Ring and Ethernet Emulated LANs Example

• Disabling LANE Flush Process Example

All examples use the automatic ATM address assignment method described in the “Method of Automatically Assigning ATM Addresses” section earlier in this chapter. These examples show the LANE configurations, not the process of determining the ATM addresses and entering them.

Default Configuration for a Single Ethernet ELAN ExampleThe following example configures four Cisco 7500 series routers for one Ethernet ELAN. Router 1 contains the LECS, the server, the BUS, and a client. The remaining routers each contain a client for the ELAN. This example accepts all default settings that are provided. For example, it does not explicitly set ATM addresses for the different LANE components that are collocated on the router. Membership in this LAN is not restricted.

Router 1 Configurationlane database example1 name eng server-atm-address 39.000001415555121101020304.0800.200c.1001.01default-name eng

interface atm 1/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database example1interface atm 1/0.1 ip address 172.16.0.1 255.255.255.0 lane server-bus ethernet eng lane client ethernet

Router 2 Configurationinterface atm 1/0atm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmi

interface atm 1/0.1ip address 172.16.0.3 255.255.255.0lane client ethernet


interface atm 2/0.1



ip address 172.16.0.4 255.255.255.0lane client ethernet



Default Configuration for a Single Ethernet ELAN with a Backup LECS and LES Example

This example configures four Cisco 7500 series routers for one ELAN with fault tolerance. Router 1 contains the LECS, the server, the BUS, and a client. Router 2 contains the backup LECS and the backup LES for this ELAN and another client. Routers 3 and 4 contain clients only. This example accepts all default settings that are provided. For example, it does not explicitly set ATM addresses for the various LANE components collocated on the router. Membership in this LAN is not restricted.

Router 1 Configurationlane database example1name eng server-atm-address 39.000001415555121101020304.0800.200c.1001.01name eng server-atm-address 39.000001415555121101020304.0612.200c 2001.01default-name eng

interface atm 1/0atm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-address lane config database example1

interface atm 1/0.1ip address 172.16.0.1 255.255.255.0lane server-bus ethernet englane client ethernet

Router 2 Configurationlane database example1_backupname eng server-atm-address 39.000001415555121101020304.0800.200c.1001.01name eng server-atm-address 39.000001415555121101020304.0612.200c 2001.01 (backup LES)default-name eng

interface atm 1/0atm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-addresslane config database example1_backup

interface atm 1/0.1ip address 172.16.0.3 255.255.255.0lane server-bus ethernet englane client ethernet







Multiple Token Ring ELANs with Unrestricted Membership ExampleThe following example configures four Cisco 7500 series routers for three emulated LANS for Engineering, Manufacturing, and Marketing, as shown in Figure 91. This example does not restrict membership in the emulated LANs.

Figure 91 Multiple Emulated LANs

In this example, Router 1 has the following LANE components:

• The LECS (there is one LECS for this group of emulated LANs)

• The LES and BUS for the ELAN for Manufacturing (man)

• The LES and BUS for the ELAN for Engineering (eng)






S50

39

Router 1

Router 2 Router 3

Router 4



• A LANE client for the ELAN for Manufacturing (man)

• A LANE client for the ELAN for Engineering (eng)

Router 2 has the following LANE components:


• A LANE client for the ELAN for Engineering (eng)



• A LANE client for the ELAN for Marketing (mkt)


• The LES and BUS for the ELAN for Marketing (mkt)


• A LANE client for the ELAN for Marketing (mkt)

For the purposes of this example, the four routers are assigned ATM address prefixes and end system identifiers (ESIs) as shown in Table 44 (the ESI part of the ATM address is derived from the first MAC address of the AIP shown in the example).

Router 1 Configuration

Router 1 has the LECS and its database, the server and BUS for the Manufacturing ELAN, the server and BUS for the Engineering ELAN, a client for Manufacturing, and a client for Engineering. Router 1 is configured as shown in this example:

!The following lines name and configure the configuration server’s database.lane database example2 name eng server-atm-address 39.000001415555121101020304.0800.200c.1001.02 name eng local-seg-id 1000 name man server-atm-address 39.000001415555121101020304.0800.200c.1001.01 name man local-seg-id 2000 name mkt server-atm-address 39.000001415555121101020304.0800.200c.4001.01 name mkt local-seg-id 3000 default-name man!! The following lines bring up the configuration server and associate! it with a database name.interface atm 1/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database example2!! The following lines configure the “man” server, broadcast-and-unknown server,! and the client on atm subinterface 1/0.1. The client is assigned to the default

Table 44 ATM Prefixes for TR-LANE Example

Router ATM Address Prefix ESI Base

Router 1 39.000001415555121101020304 0800.200c.1000

Router 2 39.000001415555121101020304 0800.200c.2000

Router 3 39.000001415555121101020304 0800.200c.3000

Router 4 39.000001415555121101020304 0800.200c.4000



! emulated lan.interface atm 1/0.1 ip address 172.16.0.1 255.255.255.0 lane server-bus tokenring man lane client tokenring man!! The following lines configure the “eng” server, broadcast-and-unknown server,! and the client on atm subinterface 1/0.2. The client is assigned to the ! engineering emulated lan. Each emulated LAN is a different subnetwork, so the “eng”! client has an IP address on a different subnetwork than the “man” client.interface atm 1/0.2 ip address 172.16.1.1 255.255.255.0 lane server-bus tokenring eng lane client tokenring eng


Router 2 is configured for a client of the Manufacturing ELAN and a client of the Engineering ELAN. Because the default ELAN name is man, the first client is linked to that ELAN name by default. Router 2 is configured as follows:

interface atm 1/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmiinterface atm 1/0.1 ip address 172.16.0.2 255.255.255.0 lane client tokenringinterface atm 1/0.2 ip address 172.16.1.2 255.255.255.0 lane client tokenring eng


Router 3 is configured for a client of the Manufacturing ELAN and a client of the Marketing ELAN. Because the default ELAN name is man, the first client is linked to that ELAN name by default. Router 3 is configured as shown here:

interface atm 2/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmiinterface atm 2/0.1 ip address 172.16.0.3 255.255.255.0 lane client tokenringinterface atm 2/0.2 ip address 172.16.2.3 255.255.255.0 lane client tokenring mkt


Router 4 has the server and BUS for the Marketing ELAN, a client for Marketing, and a client for Manufacturing. Because the default ELAN name is man, the second client is linked to that ELAN name by default. Router 4 is configured as shown here:

interface atm 3/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmiinterface atm 3/0.1 ip address 172.16.2.4 255.255.255.0 lane server-bus tokenring mkt lane client tokenring mkt



interface atm 3/0.2 ip address 172.16.0.4 255.255.255.0 lane client tokenring

Multiple Token Ring ELANs with Restricted Membership ExampleThe following example, shown in Figure 92, configures a Cisco 7500 series router for three emulated LANS for Engineering, Manufacturing, and Marketing.

The same components are assigned to the four routers as in the previous example. The ATM address prefixes and MAC addresses are also the same as in the previous example.

However, this example restricts membership for the Engineering and Marketing emulated LANs. The LECS’s database has explicit entries binding the ATM addresses of LANE clients to specified, named emulated LANs. In such cases, the client requests information from the LECS about which ELAN it should join; the LECS checks its database and replies to the client. Since the Manufacturing ELAN is unrestricted, any client not in the LECS’s database is allowed to join it.

Figure 92 Multiple Emulated LANs with Restricted Membership


Router 1 has the LECS and its database, the server and BUS for the Manufacturing ELAN, the server and BUS for the Engineering ELAN, a client for Manufacturing, and a client for Engineering. It also has explicit database entries binding the ATM addresses of LANE clients to specified, named emulated LANs. Router 1 is configured as shown here:

! The following lines name and configure the configuration server’s database.lane database example3 name eng server-atm-address 39.000001415555121101020304.0800.200c.1001.02 restricted name eng local-seg-id 1000 name man server-atm-address 39.000001415555121101020304.0800.200c.1001.01 name man local-seg-id 2000 name mkt server-atm-address 39.000001415555121101020304.0800.200c.4001.01 restricted name mkt local-seg-id 3000! ! The following lines add database entries binding specified client ATM ! addresses to emulated LANs. In each case, the Selector byte corresponds ! to the subinterface number on the specified router.






S50

39

Router 1

Router 2 Router 3

Router 4



! The next command binds the client on Router 1’s subinterface 2 to the eng ELAN. client-atm-address 39.0000014155551211.0800.200c.1000.02 name eng ! The next command binds the client on Router 2’s subinterface 2 to the eng ELAN. client-atm-address 39.0000014155551211.0800.200c.2000.02 name eng ! The next command binds the client on Router 3’s subinterface 2 to the mkt ELAN. client-atm-address 39.0000014155551211.0800.200c.3000.02 name mkt ! The next command binds the client on Router 4’s subinterface 1 to the mkt ELAN. client-atm-address 39.0000014155551211.0800.200c.4000.01 name mkt default-name man!! The following lines bring up the configuration server and associate! it with a database name.interface atm 1/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database example3!! The following lines configure the “man” server/broadcast-and-unknown server,! and the client on atm subinterface 1/0.1. The client is assigned to the default! emulated lan.interface atm 1/0.1 ip address 172.16.0.1 255.255.255.0 lane server-bus tokenring man lane client tokenring!! The following lines configure the “eng” server/broadcast-and-unknown server! and the client on atm subinterface 1/0.2. The configuration server assigns the ! client to the engineering emulated lan. interface atm 1/0.2 ip address 172.16.1.1 255.255.255.0 lane server-bus tokenring eng lane client tokenring eng


Router 2 is configured for a client of the Manufacturing ELAN and a client of the Engineering ELAN. Because the default ELAN name is man, the first client is linked to that ELAN name by default. Router 2 is configured as shown in this example:

interface atm 1/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi! This client is not in the configuration server’s database, so it will be ! linked to the “man” ELAN by default.interface atm 1/0.1 ip address 172.16.0.2 255.255.255.0 lane client tokenring! A client for the following interface is entered in the configuration ! server’s database as linked to the “eng” ELAN.interface atm 1/0.2 ip address 172.16.1.2 255.255.255.0 lane client tokenring eng


Router 3 is configured for a client of the Manufacturing ELAN and a client of the Marketing ELAN. Because the default ELAN name is man, the first client is linked to that ELAN name by default. The second client is listed in the database as linked to the mkt ELAN. Router 3 is configured as shown in this example:



interface atm 2/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi! The first client is not entered in the database, so it is linked to the! “man” ELAN by default.interface atm 2/0.1 ip address 172.16.0.3 255.255.255.0 lane client tokenring man! The second client is explicitly entered in the configuration server’s ! database as linked to the “mkt” ELAN.interface atm 2/0.2 ip address 172.16.2.3 255.255.255.0 lane client tokenring mkt


Router 4 has the server and BUS for the Marketing ELAN, a client for Marketing, and a client for Manufacturing. The first client is listed in the database as linked to the mkt emulated LANs. The second client is not listed in the database, but is linked to the man ELAN name by default. Router 4 is configured as shown here:

interface atm 3/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi! The first client is explicitly entered in the configuration server’s ! database as linked to the “mkt” ELAN.interface atm 3/0.1 ip address 172.16.2.4 255.255.255.0 lane server-bus tokenring mkt lane client tokenring mkt! The following client is not entered in the database, so it is linked to the ! “man” ELAN by default. interface atm 3/0.2 ip address 172.16.0.4 255.255.255.0 lane client tokenring

TR-LANE with 2-Port SRB ExampleThe following example configures two Cisco 7500 series routers for one emulated Token-Ring LAN using SRB, as shown in Figure 93. This example does not restrict membership in the emulated LANs.

Figure 93 2-Port SRB TR-LANE

TokenRing

TokenRing

ClientCiscoLightStream 1010

ATM switch

Configuration serverServer-bus

Client S59

93

Router 1 Router 2




Router 1 contains the LECS, the server and BUS, and a client. Router 1 is configured as shown in this example:

hostname Router1!! The following lines configure the database cisco_eng.lane database cisco_eng name elan1 server-atm-address 39.020304050607080910111213.00000CA05B41.01 name elan1 local-seg-id 2048 default-name elan1!interface Ethernet0/0 ip address 10.6.10.4 255.255.255.0!! The following lines configure a configuration server using the cisco_eng database on! the interface. No IP address is needed since we are using source-route bridging.interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database cisco_eng!! The following lines configure the server-bus and the client on the subinterface and! specify source-route bridging information.interface ATM2/0.1 multipoint lane server-bus tokenring elan1 lane client tokenring elan1 source-bridge 2048 1 1 source-bridge spanning!! The following lines configure source-route bridging on the Token Ring interface.interface TokenRing3/0/0 no ip address ring-speed 16 source-bridge 1 1 2048 source-bridge spanning!router igrp 65529 network 10.0.0.0


Router 2 contains only a client for the ELAN. Router 2 is configured as shown here:

hostname Router2!interface Ethernet0/0 ip address 10.6.10.5 255.255.255.0!! The following lines configure source-route bridging on the Token Ring interface.interface TokenRing1/0 no ip address ring-speed 16 source-bridge 2 2 2048 source-bridge spanning!! The following lines set up the signalling and ILMI PVCs.interface ATM2/0 no ip address



atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi!! The following lines set up a client on the subinterface and configure! source-route bridging.interface ATM2/0.1 multipoint ip address 1.1.1.2 255.0.0.0 lane client tokenring elan1 source-bridge 2048 2 2 source-bridge spanning!router igrp 65529 network 10.0.0.0

TR-LANE with Multiport SRB ExampleThe following example configures two Cisco 7500 series routers for one emulated Token-Ring LAN using SRB, as shown in Figure 94. Since each router connects to three rings (the two Token Rings and the ELAN “ring”), a virtual ring must be configured on the router. This example does not restrict membership in the emulated LANs.

Figure 94 Multiport SRB Token Ring ELAN


Router 1 contains the LECS, the server and BUS, and a client. Router 1 is configured as shown in this example:

hostname Router1!! The following lines configure the database with the information about the! elan1 emulated Token Ring LAN.lane database cisco_eng name elan1 server-atm-address 39.020304050607080910111213.00000CA05B41.01 name elan1 local-seg-id 2048 default-name elan1!! The following line configures virtual ring 256 on the router.source-bridge ring-group 256!interface Ethernet0/0 ip address 10.6.10.4 255.255.255.0!! The following lines configure the configuration server to use the cisco_eng database.! The Signalling and ILMI PVCs are also configured.

TokenRing

TokenRing

TokenRing

Client

Virtual ring

S59

94Cisco

LightStream 1010ATM switch

Configuration serverServer-bus

Client

TokenRing

Virtual ring

Router 1 Router 2



interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database cisco_eng!! The following lines configure the server and broadcast-and-unknown server and a client! on the interface. The lines also specify source-route bridging information.interface ATM2/0.1 multipoint lane server-bus tokenring elan1 lane client tokenring elan1 source-bridge 2048 5 256 source-bridge spanning!! The following lines configure the Token Ring interfaces.interface TokenRing3/0 no ip address ring-speed 16 source-bridge 1 1 256 source-bridge spanninginterface TokenRing3/1 no ip address ring-speed 16 source-bridge 2 2 256 source-bridge spanning!router igrp 65529 network 10.0.0.0


Router 2 contains only a client for the ELAN. Router 2 is configured as follows:

hostname Router2!! The following line configures virtual ring 512 on the router.source-bridge ring-group 512!interface Ethernet0/0 ip address 10.6.10.5 255.255.255.0!! The following lines configure the Token Ring interfaces.interface TokenRing1/0 no ip address ring-speed 16 source-bridge 3 3 512 source-bridge spanninginterface TokenRing1/1 no ip address ring-speed 16 source-bridge 4 4 512 source-bridge spanning!! The following lines configure the signalling and ILMI PVCs.interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi!! The following lines configure the client. Source-route bridging is also configured.interface ATM2/0.1 multipoint ip address 1.1.1.2 255.0.0.0



lane client tokenring elan1 source-bridge 2048 6 512 source-bridge spanning!router igrp 65529 network 10.0.0.0

Routing Between Token Ring and Ethernet Emulated LANs ExampleThis example, shown in Figure 95, configures routing between a Token Ring ELAN (trelan) and an Ethernet ELAN (ethelan) on the same ATM interface. Router 1 contains the LECS, a LES and BUS for each ELAN, and a client for each ELAN. Router 2 contains a client for trelan (Token Ring); Router 3 contains a client for ethelan (Ethernet).

Figure 95 Routing Between Token Ring and Ethernet Emulated LANs


Router 1 contains the LECS, a LES and BUS for each ELAN, and a client for each ELAN. Router 1 is configured as shown in this example:

hostname router1!! The following lines name and configures the configuration server's database.! The server addresses for trelan and ethelan and the ELAN ring number for! trelan are entered into the database. The default ELAN is trelan.lane database cisco_engname trelan server-atm-address 39.020304050607080910111213.00000CA05B41.01name trelan local-seg-id 2048name ethelan server-atm-address 39.020304050607080910111213.00000CA05B41.02default-name trelan

!! The following lines enable the configuration server and associate it! with the cisco_eng database.interface ATM2/0no ip addressatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-addresslane config database cisco_eng

!

ethelan client

Router 3

trelan client

Router 2

CiscoLightStreamATM switch

ATM 2/0.11.1.1.1

ATM 2/0.22.2.2.2

ATM 2/0.11.1.1.2

ATM 2/0.22.2.2.1

Configuration servertrelan server-busethelan server-bustrelan clientethelan client

S62

82

Router 1



! The following lines configure the tokenring LES/BUS and LEC for trelan! on subinterface atm2/0.1 and assign an IP address to the subinterface. interface ATM2/0.1 multipointip address 10.1.1.1 255.255.255.0lane server-bus tokenring trelanlane client tokenring trelan

!! The following lines configure the Ethernet LES/BUS and LEC for ethelan ! on subinterface atm2/0.2 and assign an IP address to the subinterface. interface ATM2/0.2 multipointip address 20.2.2.1 255.255.255.0lane server-bus ethernet ethelanlane client ethernet ethelan

!! The following lines configure the IGRP routing protocol to enable routing ! between ELANS.router igrp 1 network 10.0.0.0network 20.0.0.0


Router 2 contains a client for trelan (Token Ring). Router 2 is configured as follows:

hostname router2!! The following lines set up the signalling and ILMI PVCs for the interface.interface ATM2/0no ip addressno keepaliveatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmi

!! The following lines configure a Token Ring LEC on atm2/0.1 and assign! an IP address to the subinterface.interface ATM2/0.1 multipointip address 10.1.1.2 255.255.255.0lane client tokenring trelan

!! The following lines configure the IGRP routing protocol to enable routing ! between ELANS.router igrp 1network 10.0.0.0network 20.0.0.0


Router 3 contains a client for ethelan (Ethernet). Router 3 is configured as follows:

hostname router3!! The following lines set up the signalling and ILMI PVCs for the interface.interface ATM2/0no ip addressno ip mroute-cacheatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmi

!! The following lines configure an Ethernet LEC on atm2/0.1 and assign! an IP address to the subinterface.interface ATM2/0.1 multipointip address 20.2.2.2 255.255.255.0



lane client ethernet ethelan!! The following lines configure the IGRP routing protocol to enable routing ! between ELANS.router igrp 1network 10.0.0.0network 20.0.0.0

Disabling LANE Flush Process ExampleThe following example shows a running configuration and the LE_FLUSH process disabled for all LECs:

more system:running-configBuilding configuration...

Current configuration :496 bytes ! ! Last configuration change at 11:36:21 UTC Thu Dec 20 2001 ! version 12.1 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname donner_b !no lane client flush ! interface ATM0 atm preferred phy A atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi no atm ilmi-keepalive ! interface ATM0.1 multipoint lane config-atm-address 47.009181000000001007385101.0050A2FEBC43.00 lane client ethernet 100 elan1 ! line con 0 line vty 0 4 no login ! end


Configuring Token Ring LAN Emulation

This chapter describes how to configure Token Ring LAN emulation (LANE) on the Catalyst 5000 platform. This feature is supported on the following Catalyst 5000 series ATM modules:

• ATM Dual PHY OC-12 modules (WS-X5161 and WS-X5162)

• ATM Dual OC-3 modules (WS-5167 and WS-X5168)

Support for the Token Ring LANE feature was first introduced in Cisco IOS Release 12.0(7)T.

Note Beginning with Cisco IOS Release 11.3, all commands supported on the Cisco 7500 series routers are also supported on the Cisco 7000 series.


• Token Ring LANE on ATM

• Network Support

• Restrictions

• Prerequisites

• Token Ring LANE Configuration Task List

• Token Ring LANE Configuration Example



Token Ring LANE on ATMLANE bridges LAN traffic across an ATM network. The Catalyst 5000 Series Token Ring LANE feature emulates an IEEE 802.5 Token Ring LAN using ATM technology. LANE is transparent to upperlayer protocols and applications. No changes are required to existing upperlayer protocols and applications. With Token Ring LANE, Token Ring packets are encapsulated in the appropriate ATM cells and sent across the ATM network. When the packets reach the other side of the ATM network, they are deencapsulated.

Configuring Token Ring LAN EmulationToken Ring LANE on ATM


BenefitsATM is a cell-switching and multiplexing technology that combines the benefits of circuit switching (constant transmission delay and guaranteed capacity) with those of packet switching (flexibility and efficiency for intermittent traffic). Like X.25 and Frame Relay, ATM defines the interface between the user equipment (such as workstations and routers) and the network (referred to as the User-Network Interface [UNI]).

Token Ring LANE allows Token Ring LAN users to take advantage of the benefits of ATM without modifying end-station hardware or software. ATM uses connection-oriented service with point-to-point signalling or multicast signalling between source and destination devices. However, Token Ring LANs use connectionless service. Messages are broadcast to all devices on the network. With Token Ring LANE, routers and switches emulate the connectionless service of a Token Ring LAN for the end stations.

By using Token Ring LANE, you can scale your networks to larger sizes while preserving your investment in LAN technology.

Note The Catalyst 5000 series Cisco IOS Token Ring LANE software does not support Ethernet LANE or RFC 1483 permanent virtual connections (PVCs).

LANE Token Ring ComponentsLANE defines emulated LANs (ELANs). An ELAN consists of the following components:

• LANE client (LEC)—A LEC emulates a LAN interface to higher-layer protocols and applications. It forwards data to other LANE components and performs LANE address resolution functions. Each LEC is a member of only one ELAN. However, a switch or a Catalyst ATM module can include LECs for multiple ELANs; there is one LEC for each ELAN of which it is a member.

If a switch has LECs for multiple ELANs, the switch can route traffic between ELANs.

• LANE server (LES)—The LES is the control center for an ELAN. It provides joining, address resolution, and address registration services to the LECs in that ELAN. LECs can register destination unicast and multicast MAC address with the LES. The LES also handles LANE Address Resolution Protocol (LE_ARP) requests and responses and maintains a list of route descriptors that is used to support source-route bridging (SRB) over ELANs. The route descriptors are used to determine the ATM address of the next hop in the frame’s routing information field (RIF).

There is one LES per ELAN.

• LANE broadcast and unknown server (BUS)—The BUS floods unknown destination traffic and forwards multicast and broadcast traffic to LECs within an ELAN.

One combined LES and BUS is required for each ELAN.

• LANE Configuration Server (LECS)—The LECS contains the database that determines which ELAN a device belongs to (each LECS can have a different database). Each LEC contacts the LECS once to determine which ELAN it should join. The LECS returns the ATM address of the LES for that ELAN.

One LECS is required for each ATM LANE switch cloud.

The LECS database can have the following four types of entries:

– ELAN name, ATM address of LES pairs

– ELAN name and the ring number of the ELAN (local-seg-id)

Configuring Token Ring LAN EmulationNetwork Support


– LEC MAC address, ELAN name pairs

– LEC ATM template, ELAN name pairs

– Default ELAN name

Note An ELAN name must be unique on an interface. If two interfaces participate in LANE, the second interface may be in a different switch cloud.

The server assigns individual LECs to particular ELANs by directing them to the LES for the ELAN. The LECS maintains a database of LEC and server ATM or MAC addresses and their ELANs. A LECS can serve multiple ELANs.

• Fast Simple Server Redundancy Protocol (FSSRP)—Token Ring LANE relies on three servers: LECS, LES, and BUS. If any one of these servers fails, the ELAN cannot fully function.

Cisco has developed a fault tolerant mechanism known as Simple Server Redundancy Protocol (SSRP) that eliminates these single points of failure. Although there is only one LES per ELAN, SSRP allows you to configure redundant servers. You can configure servers to act as backup servers that become active if a master server fails. The priority levels for the servers determine which servers have precedence.

FSSRP is an enhancement to the SSRP. With FSSRP, LECs no longer need to go down whenever there is a change in the master LES. This uninterrupted service is achieved by connecting the LECs simultaneously to more than one LES/BUS (up to four) so that if the master LES goes down, the backup LESs are immediately available. With the basic SSRP, the LEC must go down and completely recycle before coming back up. This operation is accomplished by keeping the control connections open to all of the active LESs and BUSs in the ELAN. Although this method uses more virtual circuits (VCs), the main benefits are the transparency and speed in the switchover.

Note ELAN components coexist on one or more Cisco routers or Catalyst switches that contain an ATM module. On Cisco routers or Catalyst switches the LES and the BUS are combined into a single entity.

Network SupportThe Token Ring LANE on the Catalyst 5000 series ATM module feature supports the following networking features:

• LAN switching between ELANs and between a Token Ring ELAN and a legacy LAN

• Two-port and multiport SRB between ELANs and between ELANs and a Token Ring LAN

• SRB, source-route transparent bridging (SRT), and source-route switching

The Cisco implementation of LANE over IEEE 802.5 uses existing terminology and configuration options for Token Rings and provides for the IEEE 802.5 transport of Token Ring frames across an ATM switching fabric.

Configuring Token Ring LAN EmulationRestrictions


RestrictionsBefore you implement Token Ring LANE, be aware of the following restrictions:

Caution While VLAN Trunking Protocol (VTP) Version 2 must be enabled on a Catalyst 5000 for Token Ring to function, do not use VTP to distribute VLAN configuration information between the switches. Configure the switches to operate in VTP transparent mode and manually configure the VLANs on each switch.

• If you plan to run both Ethernet and Token Ring LANE, the Ethernet LANE software and the Token Ring LANE software must be run on separate ATM modules.

• All ATM switches have identical lists of the global LECS addresses with the identical priorities.

• Ensure that the spanning-tree port cost and priority for the ATM port are configured so that the ATM port is the preferred path (the lowest port cost with the highest priority).

• Only one LEC can be defined for each subinterface. Up to 256 subinterfaces per ATM module can be configured.

• Do not create more than one LEC for each Token Ring Bridge Relay Function (TrBRF) in each ATM module.

While you can have only one LEC for each TrBRF in each module, you can have more than one module installed. These additional modules allow you to have more than one LEC per TrBRF, which means the module can participate in more than one ELAN. The ELANs, however, cannot be parallel or the Spanning-Tree Protocol will block one of the connections.

Note Configuring more than one LEC for a TrBRF on a single ATM module will adversely affect frame forwarding.

• Do not configure parallel ELANs within a TrBRF (parallel ELANs are those ELANs that form a loop between switches).

• Do not create more than one LEC for each Token Ring Concentrator Relay Function (TrCRF) per ATM module.

• Ensure that all-routes explorer (ARE) reduction is enabled (using the set tokenring reduction enable command) on the Token Ring module.

• The number of LESs that can be defined per ELAN is unlimited; however, only one LES per ELAN can be active at a time.

• When a LECS switchover occurs, no previously joined clients are affected.

• In a LES/BUS switchover, there is a momentary loss of clients until all clients are transferred to the new LES/BUS.

• LECSs automatically come up as masters until a higher-level LECS takes priority.

• Using FSSRP, you can configure redundant LESs or BUSs and LECSs to reduce the possibility of a server failure resulting in loss of communication on the LANE network. With redundant LES/BUSs and LECSs, LANE components can switch automatically to the backup LES/BUS or LECS if the primary server fails. For specific information on how to configure FSSRP, refer to the “Configuring Fast SSRP for Redundant LANE Services” section.

Configuring Token Ring LAN EmulationPrerequisites


Note FSSRP works only with LECS and LES/BUS combinations on Cisco devices. Third-party LANE components interoperate with the LECS and LES/BUS functions of Cisco devices but cannot take advantage of the redundancy features. Additionally, FSSRP-unaware LECs on Cisco equipment cannot take advantage of FSSRP LES/BUS redundancy.

• When a higher-priority LES comes online, it bumps the current LES off the same ELAN. For a short time after power on, some clients might change from one LES to another, depending upon the order of the LESs coming up.

• If no LES/BUS pair is up or connected to the master LECS, and more than one LES/BUS is defined for an ELAN, the LECS rejects any configuration request for that specific ELAN.

• Changes made to the list of LECS addresses on ATM switches can take up to 1 minute to propagate through the network. Changes made to the LECS database regarding LES addresses take effect almost immediately.

• If no LECS is operational or reachable, the “well-known” LECS address defined by the ATM Forum is used.

• The LECS to be used can be overridden on any subinterface by entering the following command:

lane config-atm address atm-address template

Note To avoid affecting the LES/BUS or LEC redundancy, do not override any LECS, LES, or BUS addresses.

• In an underlying ATM network failure, there can be multiple master LECS and multiple active LESs or BUSs for the same ELAN, resulting in a partitioned network. Clients continue to operate normally, but transmission between partitions of the network is not possible. The system recovers when the network break is repaired.

PrerequisitesToken Ring LANE requires that the Catalyst 5000 series switch contain one of the following ATM modules running ATM software Release 4.9b or later:

• ATM Dual PHY OC-12 (WS-X5161 and WS-X5162)

• ATM Dual PHY OC-3 (WS-X5167 and WS-X5168)

These ATM modules provide an ATM network interface for the Catalyst 5000 series switch. Network interfaces reside on modular interface processors, which provide a direct connection between the high-speed synergy backplane and the external networks. The maximum number of ATM modules that the switch supports depends on the bandwidth configured.

The Catalyst 5000 series Token Ring LANE software also requires the Catalyst 5000 series supervisor engine software Release 4.3(1a) or later and one of the following switches:

• Cisco LightStream 1010 with Cisco IOS Release 12.0(1)W5 or later (recommended)

• Any ATM switch with UNI 3.0/3.1 and Interim Local Management Interface (ILMI) support for communicating the LECS address

Configuring Token Ring LAN EmulationToken Ring LANE Configuration Task List


Note If you plan to run both Ethernet and Token Ring LANE, the Ethernet LANE software and the Token Ring LANE software must be run on separate ATM modules.

Token Ring LANE Configuration Task ListTo configure Token Ring LANE, complete the tasks described in the following sections:

• Opening a Session from the Switch to the ATM Module

• Creating a LANE Plan and Worksheet

• Configuring the ATM Module from the Terminal

• Configuring the ATM Module from NVRAM

• Configuring the Prefix on the LightStream 1010 Switch

• Setting Up the Signalling PVC

• Displaying LANE Default Addresses

• Entering the LECS ATM Address on the LightStream 1010 Switch

• Configuring the LECS Database

• Binding the LECS to the ATM Interface

• Setting Up a LES/BUS and a LEC

• Configuring Redundant LANE Services

• Verifying the LANE Setup

• Monitoring and Maintaining LANE Components

Note There can be multiple LECSs in an ATM cloud.

Before configuring Token Ring LANE, you must first open a session with the ATM module in the Catalyst 5000 series switch by entering the session line configuration command from the supervisor Console> prompt. After opening the session, you see the ATM> prompt. You only have direct access to the ATM module with which you have established a session.

Note The ATM module uses a subset of the Cisco IOS software. Generally, the Cisco IOS software works the same on the ATM module as it does on routers. After configuring the ATM module, you are ready to implement LANE.

Opening a Session from the Switch to the ATM ModuleUse the session mod_num line configuration command to open a session to the ATM module from the Catalyst 5000 family switch in which the module is installed.

This example shows how to create a session to an ATM module installed in slot 5 of the Catalyst 5000 switch:

Console> (enable) session 5Trying ATM-5...



Connected to ATM-5.Escape character is '^]'. ATM>

After opening the session, you see the ATM> prompt. You then have direct access only to the ATM module with which you have established a session.

Note The ATM module uses a subset of Cisco IOS software. Generally, Cisco IOS software works the same on the ATM module as it does on routers.

To configure the ATM module, you must use the ATM configuration mode in the Cisco IOS software. To enter global configuration mode, enter the configure EXEC command at the privileged EXEC prompt (ATM#). You see the following message, which asks you to specify the terminal, the NVRAM, or a file stored on a network server as the source of configuration commands:

Configuring from terminal, memory, or network [terminal]?

If you specify terminal, the run-time configuration is used. You can then save the run-time configuration into the NVRAM. If you specify memory, the run-time configuration is updated from the NVRAM. If you specify network, the run-time configuration is updated from a file in a server on the network.

Note You cannot configure from the network.

The ATM module accepts one configuration command per line. You can enter as many configuration commands as you want.

You can add comments to a configuration file describing the commands you have entered. Precede a comment with an exclamation point (!) or pound sign (#). Comments are not stored in NVRAM or in the active copy of the configuration file. In other words, comments do not appear when you list the active configuration with the write terminal EXEC command or list the configuration in NVRAM with the show configuration EXEC command. Comments are stripped out of the configuration file when it is loaded to the ATM module.

Creating a LANE Plan and WorksheetBefore you begin to configure Token Ring LANE, you must decide whether you want to set up one or multiple ELANs. If you set up multiple ELANs, you must also decide where the servers and LECs will be located, and whether to restrict the clients that can belong to each ELAN. Bridged ELANs are configured just like any other LAN, in terms of commands and outputs. Once you have made those decisions, you can configure Token Ring LANE.

Before implementing Token Ring LANE, it might help you to begin by drawing up a plan and a worksheet for your own LANE scenario, showing the following information and leaving space to note the ATM address of each LANE component on each subinterface for each participating switch:

• Catalyst 5000 series switch interface where the LECS will be located.

• Catalyst 5000 series switch interface and subinterface where the LES/BUS for each ELAN will be located. For fault-tolerant operation, multiple servers can be on each ELAN.

• Catalyst 5000 series switch ATM modules, subinterfaces, and VLANs where the LECs for each ELAN will be located.



• Name of the default ELAN (optional). The default Token Ring ELAN is the same as the default TrCRF (1003). You can use the default Token Ring ELAN (trcrf-default) or configure a new one.

• Names of the ELANs that will have unrestricted membership.

• Names of the ELANs that will have restricted membership.

• Local segment ID for the ELAN. The local segment ID must be identical to the ring number of the TrCRF.

Note The last three items in the list above are important because they determine how you set up each ELAN in the LECS database.

Default LANE Configuration

Table 45 shows the default LANE configuration.

Configuring the ATM Module from the TerminalTo configure the ATM module from the terminal, use the following commands beginning in privileged EXEC mode:

Table 45 Default LANE Configuration

Feature Default Value

LANE components No LECS database is configured.

No LES/BUS is configured.

No LECs are configured.

PVCs ILMI and signalling PVCs are set up.

Preferred PHY (Dual PHY modules only) PHY A

Output throttling Disabled

ILMI keepalives Disabled

UNI version Autonegotiate (reverts to UNI 3.0 if autonegotiation fails)

VTP Disabled

Command Purpose

Step 1 ATM# configure terminal Selects the terminal option and enters global configuration mode.

Step 2 ATM(config)# interface atm elanname Selects an ATM ELAN subinterface.

Step 3 ATM(config-if)# lane client tokenring elanname

Identifies the ELAN attached to this subinterface as a Token Ring ELAN.

Step 4 ATM(config-if)# Ctrl-Z Exits global configuration mode.

Step 5 ATM(config)# write memory Saves the configuration file modifications to NVRAM.



In the following example, the ATM module is configured from the terminal. The interface atm 0 interface configuration command designates that ATM interface 0 is to be configured. The lane client tokenring command links TrCRF 10 to the ELAN named trcrf-10. The Ctrl-Z command quits configuration mode. The write memory command loads the configuration changes into NVRAM on the ATM module.

ATM# configure terminalATM (config)# interface atm 0ATM (config-subif)# lane client tokenring 10 trcrf-10ATM (config-subif)# Ctrl-ZATM# write memory

NVRAM stores the current configuration information in text format as configuration commands, recording only nondefault settings. The ATM module software performs a memory checksum to guard against corrupted data.

As part of its startup sequence, the ATM module startup software always checks for configuration information in NVRAM. If NVRAM holds valid configuration commands, the ATM module executes the commands automatically at startup. If the ATM module detects a problem with its NVRAM or the configuration it contains, the module goes into default configuration. Problems can include a bad checksum for the information in NVRAM or the absence of critical configuration information.

Configuring the ATM Module from NVRAMTo configure the ATM module from NVRAM, reexecute the configuration commands in privileged EXEC mode:

Configuring the Prefix on the LightStream 1010 SwitchBefore you configure LANE components on a Catalyst 5000 series switch ATM module, you must configure the Cisco LightStream 1010 switch with the ATM address prefix to be used by all LANE components in the switch cloud.

To set the ATM address prefix, use the following commands on the Cisco LightStream 1010 switch beginning in global configuration mode:

Note On the Cisco LightStream 1010 switch, the ATM address prefix is called the node ID. Prefixes must be 26 digits long. If you provide fewer than 26 digits, zeros are added to the right of the specified value to fill it to 26 digits. LANE prefixes must start with 39 or 47.

Command PurposeATM(config)# configure memory Configures the ATM module from NVRAM.

Command Purpose

Step 1 Switch(config)# atm address {atm_address | prefix...}


Step 2 Switch(config)# exit Exits global configuration mode.

Step 3 Switch# copy running-config startup-config Saves the configuration values permanently.



Note If you do not save the configured value permanently, it will be lost when the switch is reset or powered off.

To display the current prefix on the Cisco LightStream 1010 switch, use the show network EXEC command.

Setting Up the Signalling PVCYou must set up the signalling PVC and the PVC that will communicate with the ILMI on the major ATM interface of any Catalyst 5000 series switch that participates in LANE. Complete this task only once for a major interface. You need not repeat this task on the same interface even though you might configure LESs and clients on several of its subinterfaces.

To set up these PVCs, use the following commands beginning in global configuration mode:

Displaying LANE Default AddressesYou can display the LANE default addresses to make configuration easier. Complete this task for each Catalyst 5000 series switch ATM interface that participates in LANE. The show lane default-atm-address EXEC command displays default addresses for all ATM interfaces present on the switch. Write down the displayed addresses on your LANE worksheet.

To display the default LANE addresses, use the following command in global configuration mode:

Entering the LECS ATM Address on the LightStream 1010 SwitchYou must enter the LECS ATM address into each ATM switch (such as a Cisco LightStream 1010 ATM switch) connected to an ATM module in your LANE network and save the address permanently so that the value will not be lost when the switch is reset or powered off. Programming the LECS addresses allows the LESs and LECs to determine the LECS addresses dynamically through ILMI.

Command Purpose

Step 1 ATM(config)# interface atm slot/port Specifies the major ATM interface and enters interface configuration mode.

Step 2 ATM(config)# atm pvc vcd vpi vci qsaal Establishes the signalling PVC that sets up and tears down switched virtual circuits (SVCs); the vpi and vci values are usually set to 0 and 5, respectively. The vcd is the virtual channel descriptor.

Step 3 ATM(config)# atm pvc vcd vpi vci ilmi Sets up a PVC to communicate with the ILMI; the vpi and vci values are usually set to 0 and 16, respectively.

Command PurposeATM# show lane default-atm-addresses [interface atm number[.subinterface-number]]

Displays the LANE default addresses.



To enter a LECS ATM address into a LightStream 1010 switch and save it there permanently, use the following commands on the Cisco LightStream 1010 switch beginning in global configuration mode:

Configuring the LECS DatabaseThe LECS database contains LANE configuration information, including ELAN name-to-LES/BUS ATM address mappings, LEC address-to-ELAN name mappings, and the name of the default ELAN, if specified. You must configure at least one LECS database in the LANE network.

When configuring the LECS database, remember the following guidelines:

• You can configure redundant LECSs. Redundant LECSs should be configured on different devices in the LANE network. If you configure more than one LECS, make sure that all databases with the same name are identical.

• You can specify one default ELAN in the database. The LECS assigns any client that does not request a specific ELAN to the default ELAN.

• ELANs are either restricted or unrestricted. The LECS assigns a client to an unrestricted ELAN if the client specifies that particular ELAN in its configuration. However, the LECS only assigns a client to a restricted ELAN if the client is specified in the LECS’s database as belonging to that ELAN. The default ELAN should have unrestricted membership.

• If you are configuring fault tolerance, you can have any number of servers per ELAN. Priority is determined by entry order; the first entry has the highest priority unless you override it with the index option.

When setting up the LECS database remember that the following are requirements when configuring LECs:

• The VLAN name must match the ELAN name.

• The ring number defined when configuring the VLAN must match the local segment ID.

The set vlan interface configuration command assumes that any ring number you enter is in hexadecimal. Therefore, 12 is stored as the hexadecimal value 0x12. The name elan_name local-seg-id segment_number LANE database configuration command assumes that any value you enter for the local-seg-id is in decimal unless you enter it explicitly in hexadecimal. For example, to define a TrCRF with a ring number of 12 you could enter the set vlan 12 name crf12 type trcrf ring 12 parent 100 interface configuration command or the set vlan 12 name crf12 type trcrf ring 0x12 parent 100 interface configuration command.

When defining a corresponding LEC, you could enter the name crf12 local-seg-id 0x12 or name crf12 local-seg-id 18 LANE database configuration command because 18 is the decimal equivalent of 0x12.

Command Purpose

Step 1 Switch(config)# atm lecs-address-default address1 [address2...]

Specifies the LECS’s ATM address for the entire switch. Use the addresses from your LANE worksheet and specify the full 40-digit ATM address.


Step 3 Switch# copy running-config startup-config Saves the configuration value permanently.



To set up the database, complete the tasks in the following sections as appropriate for your ELAN plan and scenario:

• Setting Up the Database for the Default ELAN

• Setting Up the Database for Unrestricted-Membership ELANs

• Setting Up the Database for Restricted-Membership ELANs

Setting Up the Database for the Default ELAN

When you configure a Catalyst 5000 series switch ATM module as the LECS for one default ELAN, you need to provide the following information:

• A name for the database

• The ATM address of the LES for the ELAN

• A default name for the ELAN

In addition, you indicate that the LECS’s ATM address is to be computed automatically.

The default ELAN cannot be a restricted-membership ELAN. You do not need to specify the ATM or MAC addresses of the LECs for the default ELAN.

On the Dual PHY ATM modules, you must configure redundant LESs or BUSs and a LECS, one for each PHY.

When you configure a database with only a default unrestricted ELAN, you need not specify where the LECs are located. That is, when you set up the LECS’s database for a single default ELAN, you need not provide any database entries that link the ATM addresses of any clients with the ELAN name. All of the clients are automatically assigned to a default ELAN.

To set up the LECS for a default ELAN, use the following commands beginning in global configuration mode:

Command Purpose

Step 1 ATM(config)# lane database database-name Enters database configuration mode for the LANE database that you specify.

Step 2 ATM(lane-config-database)# name elan-name server-atm-address atm-address [index n]

Binds the name of the ELAN to the ATM address of the LES in the configuration database.

The index determines the priority. The highest priority is 0.

Enter the ATM address of the server for the specified ELAN, as noted in your LANE worksheet and obtained in the “Displaying LANE Default Addresses” section. You can have any number of servers per ELAN for fault tolerance. Priority is determined by entry order. The first entry has the highest priority unless you override it with the index number.



Note After you configure the LECS database, you must bind the LECS database to the major ATM interface (ATM0) on the ATM module. For information on how to bind the database to the interface, see the “Binding the LECS to the ATM Interface” section later on in this chapter.

Setting Up the Database for Unrestricted-Membership ELANs

When you configure unrestricted-membership ELANs in the LECS database, you create database entries that link the name of each ELAN to the ATM address of its LES/BUS.

However, you may choose not to specify where the LECs are located. That is, when you set up the LECS’s database, you do not have to provide any database entries that link the ATM addresses or MAC addresses of any clients with the ELAN name. The LECS assigns the clients to the ELANs specified in the client’s configurations.

Note In the steps listed in the task table, enter the ATM address of the server for the specified ELAN, as noted in your LANE worksheet and obtained in the Displaying LANE Default Addresses section earlier in this chapter.

Step 3 ATM(lane-config-database)# name elan-name local-seg-id segment-number

Assigns a segment number to the emulated Token Ring LAN in the configuration database.

The segment number you specify for the local-seg-id keyword must remain the same for each entry you add and it must also be identical to the ring number of the TrCRF. The set vlan interface configuration command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number LANE database configuration command assumes that any value you enter for the local-seg-id keyword is in decimal unless you enter it explicitly in hexadecimal.

Step 4 ATM(lane-config-database)# default-name elan-name

Provides a default name for the ELAN in the configuration database.

If you are setting up only a default ELAN, the elan-name argument in Step 2 and Step 3 is the same as the default ELAN name you provide in Step 4.

Step 5 ATM(lane-config-database)# exit Exits from database configuration mode and returns to global configuration mode.

Command Purpose



To configure unrestricted-membership ELANs in the LECS database, use the following commands beginning in global configuration mode:

Setting Up the Database for Restricted-Membership ELANs

When you configure restricted-membership ELANs in the LECS database, you create database entries that link the name of each ELAN to the ATM address of its LES/BUS.

Command Purpose


Step 2 ATM(lane-config-database)# name elan-name1 server-atm-address atm-address [index n]

Binds the name of the first ELAN to the ATM address of the LES/BUS for that ELAN in the configuration database.


Step 3 ATM(lane-config-database)# name elan-name2 server-atm-address atm-address [index n]

Binds the name of the second ELAN to the ATM address of the LES/BUS in the configuration database.


Repeat this step, providing a different ELAN name and ATM address for each additional ELAN in this switch cloud.

Step 4 ATM(lane-config-database)# name elan-name1 local-seg-id segment-number

Assigns a segment number to the first emulated Token Ring LAN in the configuration database.

The segment number you specify for local-seg-id must be identical to the ring number of the TrCRF. The set vlan command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number command assumes that any value you enter for the local-seg-id is in decimal unless you enter it explicitly in hexadecimal.


Assigns a segment number to the second emulated Token Ring LAN in the configuration database.

The segment number you specify for local-seg-id must be identical to the ring number of the TrCRF. The set vlan command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number command assumes that any value you enter for the local-seg-id is in decimal unless you enter it explicitly in hexadecimal.


Step 6 ATM(lane-config-database)# default-name elan-name

(Optional) Specifies a default ELAN for LECs not explicitly bound to an ELAN.

Step 7 ATM(lane-config-database)# exit Exits database configuration mode and returns to global configuration mode.



Unlike unrestricted-membership, you must also specify where the LECs are located. That is, for each restricted-membership ELAN, you provide a database entry that explicitly links the ATM address or MAC address of each client of that ELAN with the name of that ELAN.

Those client database entries specify which clients are allowed to join the ELAN. When a client requests to join an ELAN, the LECS consults its database and then assigns the client to the ELAN specified in the LECS’s database.

When clients for the same restricted-membership ELAN are located in multiple switch ATM interfaces, each client’s ATM address or MAC address must be linked explicitly with the name of the ELAN. As a result, you must configure as many client entries as you have clients for ELANs in all the switch ATM interfaces. Each client will have a different ATM address in the database entries.

To configure restricted-membership ELANs in the LECS database, use the following commands beginning in global configuration mode:

Command Purpose


Step 2 ATM(lane-config-database)# name elan-name1 server-atm-address atm-address restricted [index n]

Binds the name of the first ELAN to the ATM address of the LES/BUS for that ELAN in the configuration database.


Step 3 ATM(lane-config-database)# name elan-name2 server-atm-address atm-address restricted [index n]

Binds the name of the second ELAN to the ATM address of the LES/BUS in the configuration database.


Repeat this step, providing a different name and a different ATM address, for each additional ELAN.


Assigns a segment number to the first emulated Token Ring LAN in the configuration database.

The segment number you specify for the local-seg-id keyword must be identical to the ring number of the TrCRF. The set vlan interface configuration command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number LANE database configuration command assumes that any value you enter for the local-seg-id keyword is in decimal unless you enter it explicitly in hexadecimal.



Binding the LECS to the ATM InterfaceOnce you have created the database entries as appropriate to the type and the membership conditions of the ELANs, to enable the LECS on the selected ATM interface and switch, use the following commands beginning in global configuration mode:

Setting Up a LES/BUS and a LECFor each Catalyst 5000 series switch ATM module that will participate in LANE, set up the necessary servers and clients for each ELAN and then display and record the server and client ATM addresses. Be sure to keep track of the switch ATM interface where the LECS will eventually be located.


Assigns a segment number to the second emulated Token Ring LAN in the configuration database.

The segment number you specify for the local-seg-id keyword must be identical to the ring number of the TrCRF. The set vlan interface configuration command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number LANE database configuration command assumes that any value you enter for the local-seg-id keyword is in decimal unless you enter it explicitly in hexadecimal.


Step 6 ATM(lane-config-database)# client-atm-address atm-address-template name elan-name

Adds a database entry associating a specific client’s ATM address with a specific restricted-membership ELAN.

Repeat this step for each of the clients of each of the restricted-membership ELANs on the switch cloud, in each case specifying that client’s ATM address and the name of the ELAN with which it is linked.

Step 7 ATM(lane-config-database)# exit Exits from database configuration mode and returns to global configuration mode.

Command Purpose

Command Purpose

Step 1 ATM(config)# interface atm number If you are not currently configuring the interface, specifies the major ATM interface where the LECS is located and enters interface configuration mode.

Step 2 ATM(config-if)# lane config auto-config-atm-address

Specifies that the LECS’s ATM address will be computed by the automatic method.

Step 3 ATM(config-if)# lane config database database-name

Binds the LECS’s database name to the specified major interface, and enables the LECS.

Step 4 ATM(config-if)# exit Exits interface configuration mode.

Step 5 ATM# copy running-config startup-config Saves the configuration.



If you will have only one default ELAN, you only need to set up one server. If you will have multiple ELANs, you can set up the server for another ELAN on a different subinterface on the same interface of this switch, or you can place it on a different switch.

When you set up a server and BUS on a switch, you can combine them with a client on the same subinterface, a client on a different subinterface, or no client at all on the switch.

Depending on where your clients and servers are located, perform one of the following tasks for each LANE subinterface:

• Setting Up the LES/BUS for an ELAN

• Setting Up a LEC for an ELAN

Setting Up the LES/BUS for an ELAN

To set up the LES/BUS for an ELAN, use the following commands beginning in global configuration mode.

If the ELAN specified in Step 2 is intended to have restricted membership in the LECS database, carefully consider whether or not you want to specify its name here. You will specify the name in the LECS database when it is set up. However, if you link the client to an ELAN in this step, and through some mistake it does not match the database entry linking the client to an ELAN, this client will not be allowed to join this ELAN or any other.

If you do decide to include the name of the ELAN linked to the client in Step 2 and later want to associate that client with a different ELAN, make the change in the LECS’s database before you make the change for the client on this subinterface.

Setting Up a LEC for an ELAN

This section describes the following tasks for setting up a LEC:

• Guidelines for Setting Up a LEC

• Creating a Token Ring VLAN

• Setting Up the Token Ring VLAN on a LEC

Command Purpose

Step 1 ATM(config)# interface atm number[.subinterface-number]

Specifies the subinterface for the first ELAN on this switch and enters interface configuration mode.

Step 2 ATM(config-if)# lane server-bus tokenring elan-name1

Enables a LES/BUS for the first ELAN on the subinterface (you cannot configure more than one LES/BUS per subinterface).

Step 3 Repeat Steps 1 and 2 for all LES/BUSs you want to configure on the ATM module.

Step 4 ATM(config-if)# exit Exits interface configuration mode.

Step 5 ATM# copy running-config startup-config Saves the configuration.



Guidelines for Setting Up a LEC

The Catalyst 5000 series Token Ring LANE requires the following software:

• Catalyst 5000 series supervisor engine software Release 4.3(1a) and later

• ATM software Release 4.9(b) and later

• VTP Version 2

Note While VTP version 2 must be enabled on a Catalyst 5000 for Token Ring to function, do not use VTP to distribute VLAN configuration information between the switches. Configure the switches to operate in VTP transparent mode and manually configure the VLANs on each switch.

When you set up a LEC, follow these rules and recommendations:

• Make sure you properly configure the LECS and LES/BUS using the ATM module command-line interface (CLI) for each VLAN before creating a LEC. VTP does not set up the LECS or LES/BUS.

• In the set vlan interface configuration command, the vlan_num argument represents the VLAN number to configure, and the vlan_name argument is the name of the VLAN.

• The VLAN name must match the ELAN name and the ring number must match the local segment ID.

The set vlan interface configuration command assumes that any ring number you enter is in hexadecimal. Therefore, 0x12 or 12 is stored as the hexadecimal value 0x12. The name elan_name local-seg-id segment_number LANE database configuration command assumes that any value you enter for the local-seg-id keyword is in decimal unless you enter it explicitly in hexadecimal. For example, to define a TrCRF with a ring number of 12 you could enter the set vlan 12 name crf12 type trcrf ring 12 parent 100 interface configuration command or the set vlan 12 name crf12 type trcrf ring 0x12 parent 100 interface configuration command.

When defining a corresponding LEC, you could enter name crf12 local-seg-id 0x12 or name crf12 local-seg-id 18 because 18 is the decimal equivalent of 0x12.

• Before you can create a LEC, the TrBRF and TrCRF to which it will be associated must exist.

• Do not create more than one LEC for each TrBRF per ATM module.

While you can have only one LEC per TrBRF per module, you can have more than one module installed. This allows you to have more than one LEC per TrBRF, which means the switch can participate in more than one ELAN. The ELANs, however, cannot be parallel or the Spanning-Tree Protocol will block one of the connections.

Note Configuring more than one LEC for a TrBRF on a single ATM module will adversely affect frame forwarding.

• Ensure that all-routes explorer (ARE) reduction is enabled (using the set tokenring reduction enable interface configuration command) on the Token Ring module.

• Do not configure parallel ELANs within a TrBRF (parallel ELANs are those ELANs that form a loop between switches).

• Do not create more than one LEC for each TrCRF per ATM module.

A TrCRF can include only one enabled LEC from any ATM module.



An ATM module LEC is assigned to a TrCRF to provide connectivity to the ATM network. In this sense, an ATM module is a logical port within the TrCRF. When assigning enabled LECs to TrCRFs, the enabled LECs of any one ATM expansion module should each be assigned to different TrCRFs.

• You can change all ELAN names with the exception of VLANs 1, 1003, or 1005 whose ELAN names must remain default, trcrf-default, and trbrf-default, respectively. You cannot override the ELAN name for VLAN 1, 1003, or 1005 by using the name elan_name parameter. You can assign all other VLANs any name.

When you enter the set vlan vlan_num [name vlan_name] interface configuration command in transparent mode and do not specify the optional name elan_name parameter, the software uses the names in Table 46 by default.

If you currently have a different ELAN name for VLAN 1 or VLAN 1003, you must change the ELAN name to default (for VLAN 1) or trcrf-default (for VLAN 1003) in the LECS database. The following example shows an LECS database configuration that specifies marktng as the ELAN name for VLAN 1003:

lane database testname marktng server-atm-address 47.0091810000000061705B8301.00400B020011.01!interface ATM0no ip addressno ip route-cacheatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-address lane config database test!interface ATM0.1 multipointno ip route-cachelane server-bus tokenring marktnglane client tokenring 1003 marktng

You must change the ELAN name for VLAN 1003 from marktng to trcrf-default in the second and last lines of the display, as follows:

lane database testname default server-atm-address 47.0091810000000061705B8301.00400B020011.01!interface ATM0no ip addressno ip route-cacheatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-addresslane config database test!interface ATM0.1 multipoint

Table 46 Default VLAN ELAN Names

VLAN Number VLAN Name

1 default

2...1002 VLAN0002 through VLAN1002

1003 trcrf-default

1004 VLAN1004

1005 trbrf-default



no ip route-cachelane server-bus tokenring defaultlane client tokenring 1003 trcrf-default

Creating a Token Ring VLAN

With Token Ring, to successfully route packets between ELANs, you can only set up one LEC for each TrBRF on an ATM module. For multiple ELANs with the same TrBRF to route packets, they must be configured on either separate ATM modules or connected via an external device.

If the TrBRF and TrCRF for which you are creating a LEC do not already exist, create the Token Ring VLANs by using the following commands beginning in privileged EXEC mode:

Setting Up the Token Ring VLAN on a LEC

To set up the LEC for the Token Ring VLAN and corresponding ELAN, use the following commands on the ATM module beginning in global configuration mode:

Configuring Redundant LANE ServicesThe LANE protocol does not specify where any of the ELAN server entities should be located, but for the purpose of reliability and performance, Cisco implements these server components on its routers and LAN switches.

With Phase I LANE, only one LECS, capable of serving multiple ELANs, and only one LES per ELAN could exist for an ATM cloud. The Phase I LANE protocol did not allow for multiple LESs within an ELAN. Therefore, these components represented both single points of failure and potential bottlenecks for LANE service.

Command Purpose

Step 1 Console> (enable) set vlan vlan_num [name name] type trbrf [state {active | suspend}] [mtu mtu] bridge bridge_number [stp {ieee | ibm | auto}]

From the supervisor module, defines the TrBRF that you will associate to TrCRF as a parent

Step 2 Console> (enable) set vlan vlan_num [name name] type trcrf [state {active | suspend}] [mtu mtu] ring ring_number parent vlan_num [mode {srt | srb}] [backupcrf {off | on}] [aremaxhop hopcount] [stemaxhop hopcount]

From the supervisor module, defines the TrCRF for which you are creating a LEC.

Command Purpose

Step 1 ATM(config)# interface atm number[.subinterface-number]

Specifies the subinterface for an ELAN on this switch and enters interface configuration mode.

Step 2 ATM(config-if)# lane client tokenring vlan_id [elan-name1]

Creates a LEC for the first ELAN and specifies the VLAN number and the ELAN name to which to bind the LEC.

Step 3 ATM(config-if)# exit Exits configuration mode.

Step 4 ATM(config)# copy running-config startup-config




LANE LES/BUS and LECS redundancy corrects these limitations by allowing you to configure redundant LES/BUSs so that the LECs in an ELAN can automatically switch to a backup LES if the primary LES fails. The priority of the LES/BUS pairs is established by the order in which they are entered in the LECS database. LANE LES/BUS and LECS redundancy is always enabled. You can use this redundancy feature by configuring multiple servers.

LES/BUS and LECS redundancy works only with Cisco LECS and LES combinations. Third-party LANE server components continue to interoperate with the LECS and LES/BUS function of Cisco routers and switches, but cannot take advantage of the redundancy features.

The following servers are single points of failure in the ATM LANE system:

• LECS (configuration server)

• LES (ELAN server)

• BUS

LES/BUS and LECS redundancy eliminates these single points of failure.

Enabling Redundant LECSs

To enable redundant LECSs, enter the multiple LECS addresses to the end ATM switches, which are used as central locations for the list of LECS addresses. After entering the LECS addresses, LANE components connected to the switches can obtain the global list of LECS addresses.

Note To configure LES/BUS and LECS redundancy, you must enable multiple, redundant, and standby LECSs and multiple, redundant, and standby LES/BUSs. The LES/BUS and LEC redundancy configuration procedure guards against failure on hardware on which LANE components are running, including all Catalyst 5000 series switches. The configuration procedure is not effective for ATM network switch failures.

To enable LES/BUS and LEC redundancy, use the following commands beginning in global configuration mode:

Enabling ILMI Keepalive Timeout

If enabled, ILMI sends keepalive messages on an ongoing basis on the active physical (PHY) to the switch, and the switch responds. If the response is not obtained for the last four polls, the ILMI timer times out and the Dual PHY changes from active PHY to backup PHY. This feature is useful only if the two PHYs are connected to two different switches.

By default, this feature is disabled. To enable it, start a session to the ATM module (using the session command), and then enter the following commands:

ATM> enableATM# configure terminal

Command Purpose

Step 1 Switch(config)# atm lecs-address address Allows you to enter the multiple LECS addresses on the ATM switch.

Step 2 ATM(config)# name elan-name server-atm-address les-address [index n]

Specifies redundant LES/BUSs on the ATM module. Enter the command for each LES address on the ELAN. The index determines the priority; 0 is the highest priority.



Enter configuration commands, one per line. End with CNTL/Z.ATM(config)# interface atm0ATM(config-if)# atm ilmi-keepalive 4ATM(config-if)# endATM#

These commands enable the transmission of ILMI keepalive messages and set the time between ILMI keepalive messages to 4 seconds.

Using UNI 3.1 Signalling Support

The ATM LANE Dual PHY module supports backward compatibility with ATM switches for UNI version 3.1. On startup, ILMI negotiates between UNI versions 3.0 and 3.1, which requires no configuration. If the ILMI link autodetermination is enabled on the interface, the router or switch accepts the UNI version returned by ILMI. If the ILMI link autodetermination is unsuccessful or if ILMI is disabled, the UNI version defaults to 3.0. You can override the version number by entering the atm uni-version command. If ILMI is enabled when you enter the no version of the command, the UNI version is set to the version returned by ILMI and the link autodetermination is successful. Otherwise, the version reverts to 3.0. Enter the no atm uni-version command to override the UNI version.

Note Each ELAN is a separate subnetwork.

Configuring Fast SSRP for Redundant LANE Services

With FSSRP, you can configure redundant LES/BUS pairs for each ELAN. With FSSRP, which differs from the previously implemented SSRP, all configured LESs of an ELAN are active which means FSSRP-aware redundant LES/BUS pairs can accept join requests from any FSSRP-aware client.

LECs that are FSSRP aware have VCs established to every single LES/BUS in the ELAN. Because VC connections already exist between all LECs and LES/BUS pairs in the ELAN, the LECs can switch over to another LES/BUS pair without any noticeable delay should a failure occur.

When you configure more than one LES/BUS pair for an ELAN, one LES/BUS takes precedence over others based on the order in which they are entered into the LECS database.

Note Redundant LES/BUS pairs for a single ELAN should be configured on different ATM LANE modules in the LANE network for maximum fault tolerance.

Configuring redundant LES/BUS pairs for an ELAN is a two-part process:

• You must first configure the redundant LES/BUS pairs on subinterfaces for that ELAN.

• You must then enter the ATM addresses of the redundant LES/BUS pairs into the LECS database for the ELAN.

To configure the LES/BUS pairs, use the following commands beginning in privileged EXEC mode:

Command Purpose

Step 1 ATM# configure terminal Enters global configuration mode.

Step 2 ATM (config)# interface atm0 Specifies the major interface and enters subinterface configuration mode.



Note The LES/BUSs are not fully operational until one or more LECs are configured and the LECS database is configured and bound to the ATM module interface.

This example shows how to specify the LES/BUS for an ELAN and verify the configuration:

ATM# configure terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# interface atm0.1ATM(config-subif)# lane server-bus tokenring defaultATM(config-subif)# interface atm0.2ATM(config-subif)# lane server-bus tokenring Eng_ELANATM(config-subif)# ^ZATM# show lane serverLE Server ATM0.1 ELAN name: default Admin: up State: operationaltype: tokenring Max Frame Size: 4472ATM address: 47.00918100000000E04FACB401.00100DAACC41.01LECS used: 47.007900000000000000000000.00A03E000001.00 NOT yet connected

LE Server ATM0.2 ELAN name: Eng_ELAN Admin: up State: operationaltype: tokenring Max Frame Size: 4472ATM address: 47.00918100000000E04FACB401.00100DAACC41.02LECS used: 47.007900000000000000000000.00A03E000001.00 NOT yet connected

To add the redundant LES/BUS pairs to the LECS, use the following commands beginning in privileged EXEC configuration mode:

Step 3 ATM (config-subif)# lane fssrp Enables FSSRP on the major interface

Step 4 ATM (config-subif)# interface atm 0. subinterface-number

Specifies the subinterface for the first ELAN.

Step 5 ATM (config-subif)# lane server-bus tokenring elan-name

Enables the LES/BUS for an ELAN on the subinterface (you cannot configure more than one LES/BUS per subinterface).

Repeat Steps 2 and 3 for all LES/BUSs you want to configure on this ATM module.

Step 6 ATM (config-subif)# Ctrl-Z Exits subinterface configuration mode.

Step 7 ATM# show lane server Verifies the LES/BUS configuration.

Command Purpose

Command Purpose

Step 1 ATM# show lane server Displays the ATM address of the LES/BUS for the ELAN.

Step 2 ATM# configure terminal Enters global configuration mode.

Step 3 ATM (config)# lane database database-name Enters database configuration mode, specifying a LANE database name.

Step 4 ATM (lane-config-database)# name elan-name server-atm-address atm-address

Binds the name of the ELAN to the ATM addresses of the LES/BUS pairs in the order you want the services to fail over.

Step 5 ATM (lane-config-database)# default-name elan-name

In the configuration database, provides a default name of the ELAN.



This example shows how to display the ATM address of the LES/BUS of the default ELAN, how to configure the LECS database for the default ELAN, and how to verify the configuration:

ATM# show lane serverLE Server ATM0.1 ELAN name: default Admin: up State: operationaltype: ethernet Max Frame Size: 1516ATM address: 47.00918100000000E04FACB401.00100DAACC41.01LECS used: 47.007900000000000000000000.00A03E000001.00 NOT yet connected ATM# configure terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# lane database LANE_BackboneATM(lane-config-database)# name default server-atm-address 47.00918100000000E04FACB401.00100DAACC41.01ATM(lane-config-database)# default-name defaultATM(lane-config-database)# ^ZATM# show lane database LANE Config Server database table 'LANE_Backbone'default elan: defaultelan 'default': un-restricted server 47.00918100000000E04FACB401.00100DAACC41.01 (prio 0)

Verifying the LANE SetupOnce you have set up the LECs on the subinterfaces of an ATM module, you can display their ATM addresses by using the following command in privileged EXEC mode:

The command output shows all the subinterfaces configured for LANE. For each subinterface, the command displays and labels the ATM addresses that belong to the LES, BUS, and the LEC.

When you look at each ATM address, confirm the following items:

• The prefix is the one you set up on the switch.

• The end-system identifier field reflects the base address of the pool of MAC addresses assigned to the ATM interface plus a value that represents the specific LANE component.

• The selector byte is the same number as the subinterface (converted to hexadecimal).

Enter the show lane EXEC command on each Catalyst 5000 series switch to verify the LANE setup before you set up the LECs on the next Catalyst 5000 series switch. Print the display or make a note of these ATM addresses so that you can use it when you set up the LECS database. At this point in the configuration process, the LECs are not normally operational.

Step 6 ATM (lane-config-database)# Ctrl-Z Exits from database configuration mode.

Step 7 ATM# show lane database Displays the LECS database configuration so that you can verify your changes.

Command Purpose

Command Purpose

Router# show lane Displays the LES, BUS, and LEC ATM addresses.

Configuring Token Ring LAN EmulationToken Ring LANE Configuration Example


Monitoring and Maintaining LANE ComponentsAfter configuring LANE components on an interface or any of its subinterfaces, you can display their status on a specified subinterface or on an ELAN. To show LANE information, issue the following commands in privileged EXEC mode:

Note For descriptions of the output displayed by the commands listed above, see the description of the command documented in the Cisco IOS Switching Services Command Reference.

Token Ring LANE Configuration ExampleThis section provides a configuration example composed of two Catalyst 5000 series switches and a Cisco LightStream 1010 ATM switch as shown in Figure 96.

Figure 96 LES/BUS and LECS Configuration

Command PurposeRouter# show lane [interface atm 0 [subinterface-number | name elan-name]] [brief]

Displays the global and per-VCC LANE information for all the LANE components and ELANs configured on an interface or any of its subinterfaces.

Router# show lane bus [interface atm 0 [subinterface-number] | name elan-name] [brief]

Displays the global and per-VCC LANE information for the BUS configured on any subinterface or ELAN.

Router# show lane client [interface atm 0 [subinterface-number] | name elan-name] [brief]

Displays the global and per-VCC LANE information for all LECs configured on any subinterface or ELAN.

Router# show lane config [interface atm 0] Displays the global and per-VCC LANE information for the LECS configured on any interface.

Router# show lane database [database-name] Displays the LECS database.

Router# show lane le-arp [interface atm 0 [subinterface-number] | name elan-name]

Displays the LE_ARP table of the LECs configured on the specified subinterface or ELAN.

Router# show lane server [interface atm 0 [subinterface-number] | name elan-name] [brief]

Displays the global and per-VCC LANE information for the LES configured on a specified subinterface or ELAN.

Active

Standby

ATM switchLS1010 Backup

LES/BUSLECSLEC

LEC

Catalyst 5000switch 1

Catalyst 5000switch 2

S50

56



Example AssumptionsFor the example in Figure 96 the following assumptions apply:

• Catalyst 5000 series switches with the ATM modules installed are running ATM software Release 4.9b or later.

• Catalyst 5000 series switch 1 runs the LES/BUS and LECS on interface atm0 and the LEC on interface atm0.1.

• Catalyst 5000 series switch 2 runs LEC on interface atm0.1.

• The ATM module is installed in slot 4 of both Catalyst 5000 series switches.

• You can change the ELAN name by entering the set vlan vlan_num [name vlan_name] command.

• The ELAN on the switches is essentially a new TrCRF. The ELAN name is crf112 and the VLAN ID is 112.

• The parent TrBRF to the TrCRF 112 is brf400 (VLAN ID 400).

Configuring the TrCRF ExampleTo define the TrCRF, perform the following tasks:

Step 1 At the enable prompt, enter the following command:

Console> (enable) set vlan 112 name crf112 type trcrf ring 112 parent 400 mode srb

Step 2 To verify the configuration of the new VLAN, enter the show vlan command.

The output indicates that crf112 has been added and that brf400 is its parent:

Console> (enable) show vlan 112VLAN Name Status Mod/Ports, Vlans---- -------------------------------- --------- ----------------------------112 crf112 active

VLAN Type SAID MTU Parent RingNo BrdgNo Stp BrdgMode Trans1 Trans2---- ----- ---------- ----- ------ ------ ------ ---- -------- ------ ------112 trcrf 100112 4472 400 0x112 - - srb 0 0

VLAN AREHops STEHops Backup CRF---- ------- ------- ----------112 7 7 offConsole> (enable)

Configuring the LES/BUS and the LEC ExampleTo configure the LES/BUS and LEC, perform the following tasks:

Step 1 Set up the prefix of the ATM NSAP address for the switch.

Note The LightStream 1010 ATM switch provides a default prefix.



Step 2 Start a session to the ATM module by entering the session 4 interface configuration command. You see the following display:

Console> session 4Trying ATM-4...Connected to ATM-4.Escape character is '^]'.ATM>

Step 3 Obtain the addresses of the LES/BUS for later use by entering the enable router configuration command (to enable configuration mode) and the show lane default-atm-addresses EXEC command at the ATM prompt. You see the following display:

ATM> enableATM#ATM# show lane default-atm-addresses interface atm0

interface ATM0:LANE Client: 47.0091810000000061705b7701.00400BFF0010.**LANE Server: 47.0091810000000061705b7701.00400BFF0011.**LANE Bus: 47.0091810000000061705b7701.00400BFF0012.**LANE Config Server: 47.0091810000000061705b7701.00400BFF0013.00ATM#

Note The two asterisks (**) represent the subinterface number byte in hexadecimal.

Step 4 Using the LECS address obtained in Step 3, set the address of the default LECS in the LightStream 1010 switch by entering the configure terminal and atm lecs-address-default commands on the console of the LightStream 1010 switch. You see the following display:

Switch> enableSwitch#Switch# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Switch(config)# atm lecs-address-default 47.0091810000000061705b7701.00400BFF0013.00 1Switch(config)# endSwitch#

The commands shown in this step configure the address of the LECS in the switch. The LECS ATM NSAP address is 47.0091810000000061705b7701.00400BFF0013.00. The sequence number of this LECS address, which is 1, means it is the first LECS in this switch.

Step 5 Save the configuration to NVRAM by entering the write memory command, as follows:

ATM# write memory

Step 6 Start a LES/BUS pair on Catalyst 5000 series switch 1 by entering the interface atm0 and the lane server-bus tokenring commands in global configuration mode. On the console of Catalyst 5000 series switch 1, enter the following commands:

ATM# configure terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# interface atm0ATM(config-subif)# lane server-bus tokenring crf112ATM(config-subif)# endATM#

The commands shown in this step start a LES/BUS pair and assign the ATM 0 interface to crf112. The ELAN name is crf112, and the interface on which this LES/BUS pair is configured is atm0. The ELAN name must be the same as the VLAN name assigned to the TrCRF.



Step 7 Save the configuration in NVRAM entering the write memory command, as follows:

ATM# write memory

Step 8 Set up the LECS database on the Catalyst 5000 series switch 1.

Enter the LES address obtained in Step 3 and replace the ** with the subinterface number of the interface on which the LES/BUS is to be configured. In this example, that number is 00. Enter the lane database database_name interface configuration command, the name elan_name server-atm-address atm_address LANE database configuration command, the name elan_name local-seg-id segment_number LANE database configuration command, and the default-name elan_name commands at the ATM prompt. You see the following display:

ATM# config terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# lane database testATM(lane-config-database)# name trcf-default server-atm-address 47.0091810000000061705b7701.00400BFF0011.00ATM (lane-config-database) name crf112 local-seg-id 0x112ATM(lane-config-database)# default-name crf112ATM(lane-config-database)# exitATM#

The commands shown in this step create the LECS database. The database name is test. The ELAN name is crf112. The ELAN segment number is 112. The LES ATM NSAP address is 47.0091810000000061705b7701.00400BFF0011.00.

Note The segment number you specify for local-seg-id keyword must be identical to the ring number of the TrCRF. The set vlan command assumes that any ring number you enter is in hexadecimal. The name elan-name local-seg-id segment-number LANE database configuration command assumes that any value you enter for the local-seg-id keyword is in decimal unless you enter it explicitly in hexadecimal.

Step 9 Save the configuration in NVRAM by entering the write memory command, as follows:

ATM# write memory

Step 10 Start and bind the LECS on the Catalyst 5000 series switch 1 by entering the interface atm0, the lane config database database_name interface configuration command, and the lane config auto-config-atm-address interface configuration commands at the ATM prompt. You see the following display:

ATM# configure terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# interface atm0ATM(config-if)# lane config database testATM(config-if)# lane config auto-config-atm-addressATM(config-if)# endATM#

The commands shown in this step start the LECS. The database to use is test. The interface on which the LECS is configured is atm0.


ATM# write memory



Step 12 Start the LEC on the Catalyst 5000 series switches 1 and 2 by entering the interface atm0.1 command and the lane client tokenring 112 crf112 interface configuration command in configuration mode on the consoles of switches 1 and 2. The interface on which the LEC is configured is atm0.1. The ELAN name is default, and it is configured to emulate Token Ring. You see the following display:

ATM# configure terminalEnter configuration commands, one per line. End with CNTL/Z.ATM(config)# interface atm0.1ATM(config-subif)# lane client tokenring 112 crf112ATM(config-subif)# endATM#


ATM# write memory




Multiprotocol over ATM Overview

This chapter describes the Multiprotocol over ATM (MPOA) feature, which is supported in Cisco IOS Release 11.3 and later releases.

MPOA enables the fast routing of internetwork-layer packets across a nonbroadcast multiaccess (NBMA) network. MPOA replaces multihop routing with point-to-point routing using a direct virtual channel connection (VCC) between ingress and egress edge devices or hosts. An ingress edge device or host is defined as the point at which an inbound flow enters the MPOA system; an egress edge device or host is defined as the point at which an outbound flow exits the MPOA system.

Procedures for configuring MPOA are provided in the following chapters in this publication:

• “Configuring the Multiprotocol over ATM Client” chapter

• “Configuring the Multiprotocol over ATM Server” chapter

• “Configuring Token Ring LAN Emulation for Multiprotocol over ATM” chapter


• How MPOA Works

• MPOA Components

• MPOA Components

• Configuring an MPC/MPS



How MPOA WorksIn an NBMA network, intersubnet routing involves forwarding packets hop-by-hop through intermediate routers. MPOA can increase performance and reduce latencies by identifying the edge devices, establishing a direct VCC between the ingress and egress edge devices, and forwarding Layer 3 packets directly over this shortcut VCC, bypassing the intermediate routers. An MPOA client (MPC) provides the direct VCCs between the edge devices or hosts whenever possible and forwards Layer 3 packets over these shortcut VCCs. The MPCs must be used with MPSs resident on routers.

Multiprotocol over ATM OverviewHow MPOA Works


Figure 97 MPOA Message Flow Between MPCs and MPSs

The sequence of events shown in Figure 97 is summarized as follows:

1. MPOA resolution request sent from MPC-A to MPS-C

2. NHRP resolution request sent from MPS-C to MPS-D

3. MPOA cache-imposition request sent from MPS-D to MPC-B

4. MPOA cache-imposition reply sent from MPC-B to MPS-D

5. NHRP resolution reply sent from MPS-D to MPS-C

6. MPOA resolution reply sent from MPS-C to MPC-A

7. Shortcut VCC established

Table 47 lists and defines the MPOA terms used in Figure 97.

1240

3

MPS-C

MPC-A

Host A Host B

MPC-B

MPS-D

2

1 35

76 4

Table 47 MPOA Terms

MPOA Term Definition

MPOA resolution request A request from an MPC to resolve a destination protocol address to an ATM address to establish a shortcut VCC to the egress device.

NHRP resolution request An MPOA resolution request that has been converted to an NHRP resolution request.

MPOA cache-imposition request

A request from an egress MPS to an egress MPC providing the MAC rewrite information for a destination protocol address.

MPOA cache-imposition reply

A reply from an egress MPC acknowledging an MPOA cache-imposition request.

NHRP resolution reply An NHRP resolution reply that eventually will be converted to an MPOA resolution reply.

MPOA resolution reply A reply from the ingress MPS resolving a protocol address to an ATM address.

Shortcut VCC The path between MPCs over which Layer 3 packets are sent.

Multiprotocol over ATM OverviewHow MPOA Works


Traffic FlowFigure 97 shows how MPOA messages flow from Host A to Host B. In this figure, an MPC (MPC-A) residing on a host or edge device detects a packet flow to a destination IP address (Host B) and sends an MPOA resolution request. An MPS (MPS-C) residing on a router converts the MPOA resolution request to an NHRP resolution request and passes it to the neighboring MPS/NHS (MPS-D) on the routed path. When the NHRP resolution request reaches the egress point, the MPS (MPS-D) on that router sends an MPOA cache-imposition request to MPC-B. MPC-B acknowledges the request with a cache-imposition reply and adds a tag that allows the originator of the MPOA resolution request to receive the ATM address of MPC-B. As a result, the shortcut VCC between the edge MPCs (MPC-A and MPC-B) is set up.

When traffic flows from Host A to Host B, MPC-A is the ingress MPC and MPC-B is the egress MPC. The ingress MPC contains a cache entry for Host B with the ATM address of the egress MPC. The ingress MPC switches packets destined to Host B on the shortcut VCC with the appropriate tag received in the MPOA resolution reply. Packets traversing through the shortcut VCC do not have any DLL headers. The egress MPC contains a cache entry that associates the IP address of Host B and the ATM address of the ingress MPC to a DLL header. When the egress MPC switches an IP packet through a shortcut path to Host B, it appears to have come from the egress router.

Interaction with LANEAn MPOA functional network must have at least one MPS, one or more MPCs, and zero or more intermediate routers implementing NHRP servers. The MPSs and MPCs use LANE control frames to discover each other’s presence in the LANE network.

Caution For MPOA to work properly, you must first create an ELAN identifier for each ELAN. Use the lane config database or the lane server-bus ATM LANE command to create ELAN identifiers. These commands are described in the Catalyst 5000 Series Command Reference publication.

An MPC/MPS can serve as one or more LAN Emulation Clients (LECs). The LEC can be associated with any MPC/MPS in the router or Catalyst 5000 series switch. A LEC can be attached both an MPC and an MPS simultaneously.

Figure 98 shows the relationships between MPC/MPS and LECs.

Multiprotocol over ATM OverviewMPOA Components


Figure 98 MPC-LEC and MPS-LEC Relationships

MPOA ComponentsThe following components are required for an MPOA network:

• MPOA Client (MPC)

• MPOA Server (MPS)

• Catalyst 5000 series ATM module

• LAN Emulation (LANE)

• Next Hop Resolution Protocol (NHRP)

An MPC identifies packets sent to an MPS, establishes a shortcut VCC to the egress MPC, and then routes these packets directly over the shortcut VCC. An MPC can be a router or a Catalyst 5000 series ATM module. An MPS can be a router or a Catalyst 5000 series Route Switch Module/Versatile Interface Processor 2 (RSM/VIP2) with an ATM interface.

Note Since the RSM/VIP2 can also be used as a router, all references to router in this chapter refer to both a router and the RSM/VIP2 with an ATM interface.

ATM cloud

Interface 1

Hardwareinterfaceassociation

Hardwareinterface

association

Hardwareinterface

association

1240

2

MPC/MPS 1 MPC/MPS 3 MPC/MPS 2

Router Router Router

LEC 1 LEC 2

Interface 2

LEC 3 LEC 4

Interface 3

LEC 5 LEC 6

Multiprotocol over ATM OverviewBenefits


BenefitsMPOA provides the following benefits:

• Eliminates multiple router hops between the source and the destination points of the ATM cloud by establishing shortcuts for IP packets and other protocol packets.

• Frees the router for other tasks by reducing IP traffic.

• Provides backward compatibility as an ATM network by building upon LANE, and can be implemented using both MPOA and LANE-only devices.

Configuring an MPC/MPSTo configure an MPC/MPS, perform the following tasks:

• Define a name for the MPC/MPS.

• Attach the MPC/MPS to a major interface. This task serves two purposes:

– Assigns an ATM address to the MPC/MPS.

– Identifies an end point for initiating and terminating MPOA virtual circuits.

• Bind the MPC/MPS to multiple LECs.

Multiple MPCs/MPSs can run on the same physical interface, each corresponding to different control ATM address. Once an MPC/MPS is attached to a single interface for its control traffic, it cannot be attached to another interface unless you break the first attachment. The MPC/MPS is attached to subinterface 0 of the interface.

In Figure 98, MPC/MPS 1 is attached to interface 1; MPC/MPS 1 can only use interface 1 to set up its control virtual circuits (VCs). MPC/MPS 2 is attached to interface 3; MPC/MPS 2 can only use interface 3 to set up its control VCs.

Note An MPC/MPS can be attached to a single hardware interface only.

More than one MPC/MPS can be attached to the same interface. MPC/MPS 3 and MPC/MPS 1 are both attached to interface 1, although they get different control addresses. Any LEC running on any subinterface of a hardware interface can be bound to any MPC/MPS. However, once a LEC is bound to a particular MPC/MPS, it cannot be bound to another MPC/MPS.

Note Once a LEC has been bound to an MPC/MPS, you must unbind the LEC from the first MPC/MPS before binding it to another MPC/MPS. Typically, you will not need to configure more than one MPS in a router.

Ensure that the hardware interface attached to an MPC/MPS is directly reachable through the ATM network by all the LECs that are bound to it.

Note If any of the LECs reside on a different (unreachable) ATM network from the one to which the hardware interface is connected, MPOA will not operate properly.

Multiprotocol over ATM OverviewConfiguring an MPC/MPS



Configuring the Multiprotocol over ATM Client

This chapter describes the required and optional tasks for configuring the Multiprotocol over ATM (MPOA) client (MPC).



The MPC functionality involves ingress/egress cache management, data-plane and control-plane virtual circuit connection (VCC) management, MPOA frame processing, and participation in MPOA protocol and MPOA flow detection.

How MPC WorksThe MPC software module implements the functionality of the MPC in compliance with the ATM Forum MPOA specification. An MPC identifies packets sent to an MPOA-capable router over the nonbroadcast multi-access (NBMA) network and establishes a shortcut VCC to the egress MPC, if possible. The MPC then routes these packets directly over this shortcut VCC, bypassing the intermediate routers and enabling the fast routing of internetwork-layer packets across an NBMA network. The Catalyst 5000 series switch can be designated as an MPC. If the Catalyst 5000 series switch is configured with an RSM/VIP2 (with an ATM interface) it can be configured as an MPC or an MPS.

A router is usually designated as an MPOA server (MPS), but can also be designated as an MPC. MPC on the router is primarily meant to provide router-initiated and router-terminated shortcuts for non-NBMA networks. For this reason, MPC information in this chapter primarily refers to the Catalyst 5000 series switch, and MPS information refers to the router or the RSM/VIP2 with an ATM interface in a Catalyst 5000 series switch.

MPC Configuration Task ListTo configure an MPC on your network, perform the tasks described in the following sections. The first two sections contain required tasks; the remaining tasks are optional:

• Configuring the ELAN ID (Required)

Configuring the Multiprotocol over ATM ClientMPC Configuration Task List


• Configuring the MPC (Required)

• Configuring the MPC Variables (Optional)

• Monitoring and Maintaining the MPC (Optional)

Configuring the ELAN IDFor MPOA to work properly, a LEC must belong to an ELAN that has a defined ELAN ID. To obtain an ELAN ID, use either of the following commands in LANE database configuration mode:

Note To configure an MPC on a Catalyst 5000 series ATM module, establish connection with the ATM module, enter privileged mode, and then enter configuration mode. For information on performing these tasks, refer to the Catalyst 5000 Series Software Configuration Guide.

Caution If an ELAN ID is supplied, make sure both commands use the same elan-id value.

Configuring the MPCTo configure an MPC on your network, use the following commands in beginning in global configuration modes:

Command Purpose

Router(lane-config-dat)# name elan-name elan-id id Defines an ELAN ID for the LEC (in LANE database configuration mode).

Router(lane-config-dat)# lane server-bus ethernet elan-name [elan-id id]

Configures the LEC with the ELAN ID (in interface configuration mode).

Command Purpose

Step 1 Router(config)# mpoa client config name mpc-name In global configuration mode, defines an MPC with a specified name.

Step 2 Router(config-if)# interface atm {mod-num/port-num | number}

In interface configuration mode, specifies the ATM interface to which the MPC is associated.

Step 3 Router(config-if)# mpoa client name mpc-name In interface configuration mode, attaches an MPC to the ATM interface.

Step 4 Router(config-if)# interface atm-num.sub-interface-num

In interface configuration mode, specifies the ATM interface that contains the LEC to which you will bind the MPC.

Step 5 Router(config-if)# lane client mpoa client name mpc-name

In interface configuration mode, binds a LEC to the specified MPC.

Repeat Steps 4 and 5 for every LEC to be served by the MPC/MPS.

Configuring the Multiprotocol over ATM ClientMPC Configuration Task List


Configuring the MPC VariablesAn MPC has to be defined with a specified name before you can change its variables.

To change the variables for an MPC, use the following commands in MPC configuration mode:

Monitoring and Maintaining the MPCTo monitor and maintain the configuration of an MPC, use the following commands in EXEC mode, as needed:

Command Purpose

Step 1 Router(mpoa-client-config)# mpoa client config name mps-name

Defines an MPC with the specified name.

Step 2 Router(mpoa-client-config)# atm-address atm-address

(Optional) Specifies the control ATM address that the MPC should use (when it is associated with a hardware interface).

Step 3 Router(mpoa-client-config)# shortcut-frame-count count

(Optional) Specifies the maximum number of times a packet can be routed to the default router within shortcut-frame time before an MPOA resolution request is sent.

Step 4 Router(mpoa-client-config)# shortcut-frame-time time

(Optional) Sets the shortcut-setup frame time for the MPC.

Command PurposeRouter# show mpoa client [name mpc-name] Displays information about a specified MPC or all

MPCs.

Router# show mpoa client [name mpc-name] cache [ingress | egress] [ip-addr ip-addr]

Displays ingress and egress cache entries associated with an MPC.

Router# show mpoa client [name mpc-name] statistics Displays all the statistics collected by an MPC.

Router# clear mpoa client [name mpc-name] cache [ingress | egress] [ip-addr ip-addr]

Clears cache entries.

Router# show mpoa client [name mpc-name] [remote-device] Displays all the MPOA devices that this MPC has learned.

Router# show mpoa default-atm-addresses Displays the default ATM addresses for the MPC.

Configuring the Multiprotocol over ATM ClientMPC Configuration Example


MPC Configuration ExampleThis section contains an example of the commands needed to configure an MPC. The lines beginning with exclamation points (!) are comments explaining the command shown on the subsequent line. Figure 99 shows an example of how you can configure your system to use MPOA.

Figure 99 Example of an MPOA Configuration

The following example configures the MPC and attaches the MPC to a hardware interface:

! Define the MPC “MYMPC”mpoa client config name MYMPC

! Leave everything as defaultexit

! Specify the ATM interface to which the MPC is attachedinterface ATM 1/0

! Attach MPC MYMPC to the HW interfacempoa client name MYMPC

! Specify the ATM interface that contains the LEC to which you will bind the MPCinterface atm 1/0.1

! Bind a LANE client to the specified MPClane client mpoa client name MYMPC

! Go back up to global config modeexit

The following example shows a typical configuration file for the first MPC:

Current configuration:!version 11.3! Go to LANE database config modeexit

lane database mpoa-testhostname mpc-1! Define the ELAN ID and ATM addressname elan1 server-atm-address 47.00918100000000613E5A2F01.006070174821.01name elan1 elan-id 101name elan2 server-atm-address 47.00918100000000613E5A2F01.006070174821.02name elan2 elan-id 102! Define the MPC “mpc-1”

Catalyst5000 series

Catalyst5000series

OC-12

OC-12

OC-3ATM cloud

Cisco7200/7500/4500

series

ELAN1

LECSLES/BUS1LEC1

MPC1

MPS

LEC1LEC2

ELAN11.1.1X

ELAN21.1.2.X

ELAN2LES/BUS2LEC2

MPC2

1288

0



mpoa client config name mpc-1interface Ethernet0


! Specify the ATM interface to which the MPC is attachedinterface ATM0

atm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-address lane config database mpoa-test

! Attach MPC mpc-1 to the HW interfacempoa client name mpc-1

! Specify the ATM interface that contains the LEC to which you will bind the MPCinterface ATM0.1 multipoint

lane server-bus ethernet elan1! Bind a LANE client to the specified MPC

lane client mpoa client name mpc-1lane client ethernet 1 elan1


The following example shows a typical configuration file for the second MPC:

Current configuration:!version 11.3hostname mpc-2! Go back up to global config modeexit

! Define the MPC “mpc-2”mpoa client config name mpc-2! Specify the ATM interface to which the MPC is attachedinterface ATM0

atm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmimpoa client name mpc-2

! Specify the ATM interface that contains the LEC to which you will bind the MPCinterface ATM0.1 multipoint

lane server-bus ethernet elan2lane client mpoa client name mpc-2lane client ethernet 2 elan2





Configuring the Multiprotocol over ATM Server

This chapter describes the required and optional tasks for configuring the Multiprotocol over ATM (MPOA) server (MPS).



The MPS supplies the forwarding information used by the MPOA clients (MPCs). The MPS responds with the information after receiving a query from a client. To support the query and response functions, MPOA has adopted the Next Hop Resolution Protocol (NHRP). The MPS on the router can also terminate shortcuts.

How MPS WorksThe MPS software module implements the functionality of the MPS in compliance with the ATM Forum MPOA specification. The following sections describe the functions of MPS:

• MPS-NHRP-Routing Interaction

• Shortcut Domains

MPS-NHRP-Routing InteractionMPS must interact with the NHRP module in the router to smoothly propagate MPOA/NHRP packets end to end. MPOA frames are identical to NHRP frames except for some specific op-codes and extensions for MPOA.

The following process explains the interaction of MPS and NHRP:

1. MPS converts MPOA resolution requests to NHRP requests and sends it either to the next hop MPS or to the Next Hop Server (NHS), depending on the configuration. MPS searches for the next hop routing information to determine the interface and sends the packet with correct encapsulation to an MPS or an NHS.

Configuring the Multiprotocol over ATM ServerMPS Configuration Task List


2. NHS sends resolution requests to MPS when the next hop is on a LAN Emulation (LANE) cloud or when NHS is unsure of the packet destination. MPS may do further processing, such as prompt NHS to terminate the request or throw away the packet.

3. NHS sends resolution replies to MPS when the next hop interface is LANE or when the replies terminate in the router. Then MPS sends an MPOA resolution reply to the MPC.

Shortcut DomainsWithin a router, it is possible to permit shortcuts between one group of LAN Emulation Clients (LECs) and deny it between some other groups of LECs. Cisco introduces a notion of network ID associated with an MPS. By default, all the MPSs in a router get a network ID of 1.

If the administrator wants to segregate traffic, then MPSs can be given different network IDs, in effect preventing shortcuts between LECs served by different MPSs. This can be configured in the definition of an MPS database.

If a router has both MPS and NHRP configured, then the same network ID is required to facilitate requests, replies, and shortcuts across the MPS and NHRP. The interface-specific NHRP command (ip nhrp network-id) must be the same for an MPS; otherwise, there will be a disjointed network.

MPS Configuration Task ListTo configure an MPS on your network, perform the following tasks:

• Configuring the ELAN ID (Required)

• Configuring the MPS (Required)

• Configuring the MPS Variables (Optional)

• Monitoring and Maintaining the MPS (Optional)

Configuring the ELAN IDFor MPOA to work properly, a LANE client must have an ELAN ID for all ELANs represented by the LANE clients. To configure an ELAN ID, use either of the following commands in lane database configuration mode or in interface configuration mode when starting up the LAN Emulation Client Server (LECS) for that ELAN:

Caution If an ELAN ID is supplied by both commands, make sure that the ELAN ID matches in both.

Command PurposeRouter(lane-config-dat)# name elan-name elan-id id Configures the ELAN ID in the LECS database to

participate in MPOA.

Router(lane-config-dat)# lane server-bus {ethernet | tokenring} elan-name [elan-id id]

Configures the LAN Emulation Server (LES) with the ELAN ID to participate in MPOA.

Configuring the Multiprotocol over ATM ServerMPS Configuration Task List


Configuring the MPSTo configure an MPS, use the following commands beginning in global configuration mode. The MPS starts functioning only after it is attached to a specific hardware interface:

Configuring the MPS VariablesAn MPS must be defined with a specified name before you can change the MPS variables specific to that MPS.

To change MPS variables specific only to a particular MPS, use the following commands beginning in MPS configuration mode:

Command Purpose

Step 1 Router(config)# mpoa server config name mps-name

In global configuration mode, defines an MPS with the specified name.

Step 2 Router(config)# interface atm {slot/port | number}

Specifies the ATM interface to attach the MPS.

Step 3 Router(config-if)# mpoa server name mps-name In interface configuration mode, attaches the MPS to the ATM interface.

Step 4 Router(config-if)# interface atm {slot/port.subinterface-number | number.subinterface-number}

Specifies the ATM interface to bind the MPS to a LEC.

Step 5 Router(config-subif)# lane client mpoa server name mps-name

In subinterface configuration mode, binds a LANE client to the specified MPS.

Command Purpose

Step 1 Router(mpoa-server-config)# mpoa server config name mps-name

Defines an MPS with the specified name.

Step 2 Router(mpoa-server-config)# atm-address atm-address

(Optional) Specifies the control ATM address that the MPS should use (when it is associated with a hardware interface).

Step 3 Router(mpoa-server-config)# holding-time time (Optional) Specifies the holding time value for the MPS-p7 variable of the MPS.

Step 4 Router(mpoa-server-config)# keepalive-lifetime time

(Optional) Specifies the keepalive lifetime value for the MPS-p2 variable of the MPS.

Step 5 Router(mpoa-server-config)# keepalive-time time

(Optional) Specifies the keepalive time value for the MPS-p1 variable of the MPS.

Step 6 Router(mpoa-server-config)# network-id id (Optional) Specifies the network ID of the MPS.

Configuring the Multiprotocol over ATM ServerMPS Configuration Example


Monitoring and Maintaining the MPSTo monitor and maintain the configuration of an MPS, use the following commands in EXEC mode, as needed:

MPS Configuration ExampleThis section contains an example of the commands needed to configure an MPS. The lines beginning with exclamation points (!) are comments explaining the command shown on the following line. Figure 100 shows an example of how you can configure your system to utilize MPOA.

Figure 100 Example of an MPOA Configuration

The following example configures the MPS and attaches the MPS to a hardware interface:

Command PurposeRouter# show mpoa default-atm-addresses Displays default ATM addresses for an MPS.

Router# show mpoa server [name mps-name] Displays information about a specified server or all servers depending on the specified name of the required server.

Router# show mpoa server [name mps-name] cache[ingress | egress] [ip-address ip-address]

Displays ingress and egress cache entries associated with a server.

Router# show mpoa server [name mps-name] statistics Displays all the statistics collected by a server including the ingress and egress cache entry creations, deletions, and failures.

Router# clear mpoa server [name mps-name] cache [ingress | egress] [ip-addr ip-addr]

Clears cache entries.

Router# mpoa server name mps-name trigger ip-address ip-address [mpc-address mpc-address]

Originates an MPOA trigger for the specified IP address to the specified client. If a client is not specified, the MPOA is triggered to all the clients.

Catalyst5000 series

Catalyst5000series

OC-12

OC-12

OC-3ATM cloud

Cisco7200/7500/4500

series

ELAN1

LECSLES/BUS1LEC1

MPC1

MPS

LEC1LEC2

ELAN11.1.1X

ELAN21.1.2.X

ELAN2LES/BUS2LEC2

MPC2

1288

0



! Define the MPS “MYMPS”mpoa server config name MYMPS

! Leave everything as defaultexit

! Enter into interface config modeinterface ATM 1/0

! Attach MPS MYMPS to the HW interfacempoa server name MYMPS


The following example shows a typical MPS configuration file:

version 11.3hostname MPS! Define the MPS “mps”mpoa server config name mps! Specify the ATM interface to which the MPS is attachedinterface ATM4/0

no ip addressatm pvc 1 0 5 qsaalatm pvc 2 0 16 ilmilane config auto-config-atm-address mpoa server name mps

! Specify the ATM interface that contains the LEC to which you will bind the MPSinterface ATM4/0.1 multipoint

ip address 1.1.1.2 255.255.255.0lane client mpoa server name mpslane client ethernet elan1

interface ATM4/0.2 multipointip address 1.1.2.1 255.255.255.0lane client mpoa server name mpslane client ethernet elan2

end




Configuring Token Ring LAN Emulation for Multiprotocol over ATM

This chapter describes the required and optional tasks for configuring the MPOA for Token Ring Networks feature.



The MPOA for Token Ring Networks feature allows Token Ring hosts on an ATM network to communicate over direct paths (called shortcuts) through the ATM network. These shortcuts bypass the intermediate router hops that otherwise would be encountered in the default path.

How Token Ring MPOA WorksToken Ring Multiprotocol over ATM (MPOA) is an extension to LAN Emulation (LANE). It allows Token Ring LANE clients to forward IP packets between subnets to other Token Ring LANE clients through a shortcut in the ATM network. The Token Ring LANE clients have an MPOA client (MPC) communicating with an MPOA server (MPS) to establish this shortcut.

Token Ring LANE for MPOA Configuration Task ListTo configure Token Ring LANE for MPOA, perform the tasks described in the following sections:

• Configuring a Token Ring LEC

• Configuring the LECS Database

• Configuring the LES/BUS

Configuring Token Ring LAN Emulation for Multiprotocol over ATMToken Ring LANE for MPOA Configuration Task List


Configuring a Token Ring LECFor MPOA operation, a LEC must be associated with an MPS, an MPC, or both. Once a LEC is bound to a particular MPS/MPC, it cannot be bound to another MPS/MPC at the same time.

The LEC must also be associated with a physical interface or subinterface, which may be different from the physical interface associated with the MPS or MPC. For proper operation, all interfaces must belong to the same ATM network.

To configure a Token Ring LEC, use the following commands beginning in global configuration mode:

Configuring the LECS DatabaseTo configure the LECS database, use the following commands in beginning global configuration mode:

Configuring the LES/BUSTo configure the LES/BUS, use the following commands in beginning global configuration mode:

Command Purpose

Step 1 Router(config)# interface atm {slot/port.subinterface-number | number.subinterface-number}

Specifies the ATM interface to be associated with the LEC.

Step 2 Router(config-if)# lane client tokenring [elan-name]

Defines a Token Ring LEC on a specified ELAN name.

Step 3 Router(config-if)# lane client mpoa server mps-name

(Optional) Binds a Token Ring LEC to an MPS.

Step 4 Router(config-if)# lane client mpoa client mpc-name

(Optional) Binds a Token Ring LEC to an MPC.

Command Purpose


Step 2 Router(lane-config-dat)# name elan-name server-atm-address atm-address

Binds the name of the ELAN to the ATM address of the LES.

Step 3 Router(lane-config-dat)# name elan-name elan-id id

Defines the ELAN ID in the LECS database to participate in MPOA.

Step 4 Router(lane-config-dat)# name elan-name local-seg-id id

Configures the local segment ID number.

Command Purpose

Step 1 Router(config)# interface atm {slot/port.subinterface-number | number.subinterface-number}

Specifies the ATM subinterface to be associated with the LES/BUS.

Step 2 Router(config-if)# lane server-bus tokenring elan-name [elan-id elan-id]

Defines a Token Ring LES/BUS on the named ELAN. The ELAN ID is optional.

Configuring Token Ring LAN Emulation for Multiprotocol over ATMToken Ring LANE Configuration Examples


Token Ring LANE Configuration ExamplesThis section provides the following sample configurations of MPOA in a Token Ring LANE environment:

• MPOA Token Ring LANE Configuration in an IP-Routed Domain Example

• MPOA Token Ring LANE Configuration in an IP SRB-Routed Domain Example

MPOA Token Ring LANE Configuration in an IP-Routed Domain ExampleFigure 101 illustrates MPOA in a Token Ring LANE environment where MPC-to-MPC shortcuts are established between Token Ring LANE edge routers that reside in different IP-routed domains.

Figure 101 Token Ring MPOA—MPC to MPC Shortcut in an IP Routed Environment

The following commands show a sample configuration for Router-1 in Figure 101:

hostname Router-1!ip routing!! Define the MPOA Client (mpc-1) configuration.!mpoa client config name mpc-1!! Configure an IP address on the Token Ring interface.!

TR-ELAN2/LIS 2

Host A Host B

Router-2MPS-1

Shortcut VCC

Shortcut pathRouter-1MPC-1

Router-3MPS-2

Router-4MPC-2

TR-ELAN2/LIS 2

TR-ELAN 3IP Subnet 3

TR-ELAN 1IP Subnet 1

TokenRing IPSubnet

4

TokenRing IPSubnet

5

1824

5



interface TokenRing1/0 ip address 5.5.5.2 255.255.255.0 ring-speed 16!! Configure a config-server and bind it to its database (mpoa-db).! Attach the MPOA client mpc-1 to its ATM interface.!interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database mpoa-db mpoa client name mpc-1!! Configure a LANE server-bus and LANE client on ELAN 1. Bind the! LANE client to its MPOA Client (mpc-1). !interface ATM2/0.1 multipoint ip address 1.1.1.1 255.255.255.0 lane server-bus tokenring 1 lane client mpoa client name mpc-1 lane client tokenring 1!router eigrp 1 network 1.0.0.0 network 5.0.0.0!end


hostname Router-2!ip routing!! Configure the config-server database mpoa-db with configuration! for ELANs 1 to 3!lane database mpoa-db name 1 server-atm-address 47.0091810000000060705BFA01.00000CA05F41.01 name 1 local-seg-id 1000 name 1 elan-id 100 name 2 server-atm-address 47.0091810000000060705BFA01.00000CA05B41.01 name 2 local-seg-id 2000 name 2 elan-id 200 name 3 server-atm-address 47.0091810000000060705BFA01.00000CA05B41.03 name 3 local-seg-id 3000 name 3 elan-id 300!! Define the MPOA Server (mps-1) configuration.mpoa server config name mps-1!! Configure the signalling and ILMI PVCs. Also configure a config-server! and attach the MPOA server (mps-1) to its ATM interface.!interface ATM4/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database mpoa-db mpoa server name mps-1!! Configure a Token Ring LANE client on ELAN 1 and bind the LANE



! client to its MPOA server (mps-1). !interface ATM4/0.1 multipoint ip address 1.1.1.2 255.255.255.0 lane client mpoa server name mps-1 lane client tokenring 1!! Configure a Token Ring LANE client on ELAN 2 and bind the LANE! client to its MPOA server (mps-1)!interface ATM4/0.2 multipoint ip address 2.2.2.1 255.255.255.0 lane client mpoa server name mps-1 lane client tokenring 2!router eigrp 1 network 1.0.0.0 network 2.0.0.0!end


hostname Router-3!ip routing!! Defines the MPOA Server (mps-2) configuration.mpoa server config name mps-2!! Configure the signalling and ILMI PVCs and attach the MPOA! server (mps-2) to its ATM interface.!interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi mpoa server name mps-2!! Configure a Token Ring LANE client and LANE server-bus on ELAN 2! and bind the LANE client to its MPOA server (mps-2)!interface ATM2/0.1 multipoint ip address 2.2.2.2 255.255.255.0 lane server-bus tokenring 2 lane client mpoa server name mps-2 lane client tokenring 2!! Configure a Token Ring LANE client on ELAN 3 and bind the LANE! client to its MPOA server (mps-2)!interface ATM2/0.3 multipoint ip address 3.3.3.1 255.255.255.0 lane server-bus tokenring 3 lane client mpoa server name mps-2 lane client tokenring 3!router eigrp 1 network 2.0.0.0 network 3.0.0.0!end




hostname Router-4!ip routing!! Define the MPOA client (mpc-2) configuration.!mpoa client config name mpc-2!! Configure the Token Ring interface!interface TokenRing1/0 ip address 4.4.4.1 255.255.255.0 ring-speed 16!! Configure the signalling and ILMI PVCs and attach the MPOA! client to its ATM interface.!interface ATM2/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi mpoa client name mpc-2!! Configure a Token Ring LANE client on ELAN 3 and bind the LANE! client to its MPOA client (mpc-2). !interface ATM2/0.1 multipoint ip address 3.3.3.2 255.255.255.0 lane client mpoa client name mpc-2 lane client tokenring 3!router eigrp 1 network 3.0.0.0 network 4.0.0.0!end



MPOA Token Ring LANE Configuration in an IP SRB-Routed Domain ExampleFigure 102 illustrates MPOA in a Token Ring LANE environment where MPC-to-MPC shortcuts are established between a Token Ring LANE edge device and a Token Ring LANE router that reside in an IP SRB domain and IP-routed domains.

Figure 102 Token Ring MPOA—MPC to MPC Shortcut in an IP SRB-Routed Environment


hostname Router-1!ip routing!! Configure the config-server database mpoa-db with configuration! for ELANs 1 to 3lane database mpoa-db name 1 server-atm-address 47.0091810000000060705BFA01.00000CA05F41.01 name 1 local-seg-id 1000 name 1 elan-id 100 name 2 server-atm-address 47.0091810000000060705BFA01.00000CA05B41.01 name 2 local-seg-id 2000 name 2 elan-id 200 name 3 server-atm-address 47.0091810000000060705BFA01.00000CA05B41.03 name 3 local-seg-id 3000 name 3 elan-id 300!! Define the MPOA Server (mps-1) configuration.mpoa server config name mps-1

Router-1MPS-1

Shortcut VCC

IP with no RIF

Shortcut path

IP w

ith R

IF

Edge deviceMPC-1(SRB)

Host A

Multiring IP

Router-2MPS-2

Host B

TokenRing IPsubnet

418

349

Router-3MPC-2

IP w

ith n

o R

IF

TokenRing IPsubnet

1

TR-ELAN 1IP subnet 1

TR-ELAN 3IP subnet 3

TR-ELAN2/LIS 2



!! Configure the signalling and ILMI PVCs. Also configure a config-server! and attach the MPOA server (mps-1) to its ATM interface.interface ATM4/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi lane config auto-config-atm-address lane config database mpoa-db mpoa server name mps-1 !! Configure a Token Ring LANE client on ELAN 1 and bind the LANE! client to its MPOA server (mps-1). The multiring ip configuration! is required to terminate the RIF for IP packets on the ELAN.interface ATM4/0.1 multipoint ip address 1.1.1.2 255.255.255.0 lane client mpoa server name mps-1 lane client tokenring 1 multiring ip!! Configure a Token Ring LANE client on ELAN 2 and bind the LANE! client to its MPOA server (mps-1)! interface ATM4/0.2 multipoint ip address 2.2.2.1 255.255.255.0 lane client mpoa server name mps-1 lane client tokenring 2!! router eigrp 1 network 1.0.0.0 network 2.0.0.0!end


hostname Router-2!ip routing!! Defines the MPOA Server (mps-2) configuration.mpoa server config name mps-2!!! Configure the signalling and ILMI PVCs and attach the MPOA! server (mps-2) to its ATM interface.interface ATM2/0 no ip address atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi mpoa server name mps-2!! Configure a Token Ring LANE client and LANE server-bus on ELAN 2! and bind the LANE client to its MPOA server (mps-2)!interface ATM2/0.1 multipoint ip address 2.2.2.2 255.255.255.0 lane server-bus tokenring 2 lane client mpoa server name mps-2 lane client tokenring 2!! Configure a Token Ring LANE client on ELAN 3 and bind the LANE! client to its MPOA server (mps-2)!



interface ATM2/0.3 multipoint ip address 3.3.3.1 255.255.255.0 lane server-bus tokenring 3 lane client mpoa server name mps-2 lane client tokenring 3!router eigrp 1 network 2.0.0.0 network 3.0.0.0!end


hostname Router-3!ip routing!! Define the MPOA client (mpc-2) configuration.mpoa client config name mpc-2!!! Configure the Token Ring interfaceinterface TokenRing1/0 ip address 4.4.4.1 255.255.255.0 ring-speed 16!! Configure the signalling and ILMI PVCs and attach the MPOA! client to its ATM interface.!interface ATM2/0 atm pvc 1 0 5 qsaal atm pvc 2 0 16 ilmi mpoa client name mpc-2!! Configure a Token Ring LANE client on ELAN 3 and bind the LANE! client to its MPOA client (mpc-2).! interface ATM2/0.1 multipoint ip address 3.3.3.2 255.255.255.0 lane client mpoa client name mpc-2 lane client tokenring 3!router eigrp 1 network 3.0.0.0 network 4.0.0.0!end

Index

IN-455Cisco IOS Switching Services Configuration Guide

I N D E X

Symbols

<cr> xxxiii

? command xxxii

A

access lists

creating XC-170

IPX MLS

configuration (example) XC-295

overview XC-261

restrictions XC-286

accounting

per VLAN XC-304

statistics XC-140

addresses

Layer 2 MAC XC-7

Layer 3 XC-7

mapping XC-7

addressing, in VLANs XC-312

AppleTalk

AppleTalk over IEEE 802.10 in VLAN, configuration (example) XC-341

fast switching

disabling XC-14

enabling XC-11

IEEE 802.10 encapsulation, enabling for XC-340

over encapsulating VLAN interfaces, configuration (example) XC-329

over IEEE 802.10 encapsulation XC-339

subinterface, configuring on XC-340

subinterface, routing over

VLAN, customizing XC-340

TR LANE support XC-362

VLAN subinterfaces, routing over XC-339

appletalk cable-range command XC-315, XC-340, XC-345

appletalk route-cache command XC-13, XC-14

appletalk routing eigrp command XC-315, XC-340, XC-344

appletalk zone command XC-315, XC-340, XC-345

APPN (Advanced Peer-to-Peer Networking), TR LANE support XC-362

ATM (Asynchronous Transfer Mode)

extended label interface XC-173

forum XC-220

Forum protocols XC-139

interface, configuring XC-219

interfaces XC-163

label switches

partitioning resources XC-84

VCI table entries, creating XC-84

LANE

in VLANs XC-310

LECs XC-311

LESs XC-311

NDIS-compliant LAN drivers XC-310

ODI-compliant LAN drivers XC-310

protocol definition XC-310

LSR network configuration XC-221

MPLS subinterface XC-219

port adapter XC-134

subinterface XC-169

switches XC-164, XC-220

VCs XC-95

with LSRs, configuring XC-162

WRED XC-216

atm-address command XC-367, XC-435, XC-441

Index


ATM LANE

address

wildcards in templates XC-365

MAC address and ESI field XC-364

atm lecs-address command XC-369

atm lecs-address-default command XC-369

ATM-LSR (ATM label switch router)

adding redundancy XC-126

definition XC-113

atm manual-well-known-vc delete command XC-233

atm pvc ilmi command XC-368

atm pvc qsaal command XC-368

ATM switches


compared to an ATM label switch XC-84

functioning as an IP router XC-84

interfaces, configuring XC-115

LSC

redundancy

configuring XC-125partitioning XC-125

autonomous systems

definition XC-103

EBGP routing, configuring XC-159

forwarding packets XC-107

maintaining the LFIB XC-106

routing between XC-104

B

backbone

network XC-96

provider XC-99

services XC-94

backbone router

interfaces for TMS collection, setting XC-41

bandwidths

in virtual trunks XC-117

on XTagATM interfaces XC-125

specifying XC-124

Banyan VINES

in VLANs XC-312

LANE support XC-362

over ISL encapsulation XC-316



benefits XC-140

benefits of QoS enhancements

service provider benefits XC-113

BGP (Border Gateway Protocol)

PE to CE routing sessions, configuring XC-151

routing sessions, configuring XC-150

bit settings XC-110

bottlenecks XC-95

bounded delay XC-111

bridge-group command XC-347, XC-348

bridging domain XC-302

broadcast-and-unknown server (BUS) XC-361

broadcasts

control XC-304

domain XC-302

Layer 2 XC-303

management

in VLANs XC-312

burst size XC-216

BUS XC-354

BXM (Broadband Switch Module)

locating XC-174

supported virtual interfaces XC-118

C

cache

MLS XC-248

cache imposition reply

MPOA XC-428

cache-imposition request

MPOA XC-428

Index


candidate packet XC-250

capturing flows XC-139

CAR (committed access rate)

as a QoS building block XC-162

configuring XC-216

for packet classification XC-111

function XC-111, XC-166

ingress label switching router, using XC-167

MLS

restrictions XC-263

rate policies XC-216, XC-218

carriage return (<cr>) xxxiii

cautions, usage in text xxvii

CE (customer edge)

routing sessions XC-151, XC-152

CEBGP

assigning labels XC-110

function in sub-autonomous systems XC-109

CEF (Cisco Express Forwarding)

accounting XC-40

benefits XC-19

components

adjacency tables XC-20

FIB XC-20

configuration task list XC-36

description XC-8, XC-19

distributed tunnel switching, configuring XC-43

enabling XC-37, XC-172

FIB XC-35

load balancing

per-destination, configuring XC-37

per-destination, disabling XC-38

per-packet, configuring XC-37

NetFlow policy routing XC-63

network accounting, configuring XC-40

operation modes

central CEF mode XC-22

distributed CEF mode XC-22

requirement XC-80

sample network topology (figure) XC-20

supported media XC-22

virtual profiling XC-34

CEF mode

(figure) XC-23

centralized service XC-95

CIR (committed information rate) XC-218

Cisco.com xxviii

Cisco 6400 Universal Access Concentrator

configuring XC-173, XC-227

edge LSR, disabling XC-134

MPLS LSC, using XC-114, XC-133

virtual trunks, creating XC-232

Cisco 7200 series routers

MPLS LSC, using XC-114

virtual trunks, creating XC-229

Cisco 7500 series routers XC-162

Cisco BPX series switches

multi-vc, configuring XC-228

supported XC-114

Cisco Catalyst 5000 series switches XC-433

Cisco Catalyst switches

in VLANs XC-310

Cisco IGX series switches

supported XC-114

Cisco IOS configuration changes, saving xxxvi

Cisco LightStream 100 ATM switches XC-368

LANE ATM address prefix XC-364

LANE ATM address prefix, configuring XC-367

LANE configuration server’s ATM address on the Cisco LightStream 100 switches XC-366

software version, TR-LANE XC-363

Cisco LightStream 1010 ATM switches

LANE configuration server’s ATM address on the Cisco LightStream 1010 switches XC-366

software version, TR-LANE XC-363

class

premium XC-170

standard XC-170

Index


class maps, configuring XC-166

clear cef linecard command XC-47

clear ip cef inconsistency command XC-47

clear ip flow stats command XC-68

clear ip mds forwarding command XC-299

clear ip pim interface count command XC-299

clear mpoa client cache command XC-435

clear mpoa server cache command XC-442

client-atm-address name command XC-373

clns route-cache command XC-15

closed user groups XC-95

cnfrsrc command XC-137

command modes, understanding xxxi to xxxii

commands

context-sensitive help for abbreviating xxxii

default form, using xxxv

no form, using xxxv

command syntax

conventions xxviii

displaying (example) xxxiii

communication

between hosts XC-94

components

IPX MLS XC-258

MLSP XC-258

MLS-SE XC-258

NFCC XC-258MSL-RP XC-258

confederations

definition XC-104

EBGP routing, configuring XC-159

function XC-109

configurations, saving xxxvi

congestion avoidance

MPLS QoS XC-165

congestion management

MPLS QoS XC-111

connectionless

architecture XC-95

IP environment XC-94

network XC-95

service XC-94

connection-oriented overlay XC-94

connection routing software XC-121

connections

ATM virtual XC-95

meshed XC-95

private XC-95

connectivity XC-95, XC-96

content hosting XC-95

copy command

running-config startup-config command XC-156, XC-158

cos-map function XC-170

D

data encryption

MLS

restrictions XC-263

data hosting network commerce XC-94

dCEF (distributed CEF)

description XC-8

disabling XC-37

distributed tunnel switching, configuring XC-43

enabling XC-37

IPC, using XC-24

load balancing, disabling XC-38, XC-39

mode XC-24

mode (figure) XC-24

NetFlow policy routing XC-63

DECnet

fast switching

disabling XC-15

in VLANs XC-312

LANE support XC-362

over ISL encapsulation


configuring XC-316

Index


VLAN encapsulation format, defining XC-317


decnet cost command XC-317

decnet route-cache command XC-14

decnet routing command XC-317

default-name command XC-370, XC-372

discard policy XC-162

distributed fair queueing, configuring XC-170

distributed VIP switching XC-68

documentation, ordering xxix

documentation CD-ROM xxix

documentation conventions xxvii

documentation feedback, providing xxix

documentation modules xxiii to xxv

domain

bridging XC-302

broadcast XC-302

DRiP (Duplicate Ring Protocol)

database, enabling XC-320

drop mechanism XC-217

dropping packets XC-162

drop probability XC-162

E

EBGP

function in autonomous systems XC-103

parameters XC-151

edge LSR


allowing unlimited XC-113


disabling XC-133, XC-134, XC-139

using as an MPLS LSC XC-116

egress edge device XC-427

emulated LANs

default XC-370

restricted membership XC-370, XC-372

adding database entries for clients XC-412


database entries for all clients, configuring XC-372

database entries for clients, adding XC-373

setting up database for XC-372

unrestricted membership XC-370


setting up database for XC-371

enabler packet XC-251

encapsulation dot1q command XC-347, XC-348

encapsulation format

defining XC-315, XC-319, XC-341

IEEE 802.10 XC-315, XC-339, XC-341

ISL XC-315, XC-316, XC-319, XC-325, XC-326, XC-327

ISL, configuring XC-316

Security Data Exchange (sde) XC-315, XC-341

VLANs, defining XC-341

encapsulation isl command XC-315, XC-316, XC-317, XC-319, XC-322, XC-325, XC-326, XC-327, XC-328

encapsulations

AppleTalk Phase II

in VLANs XC-312

formats

defining XC-320, XC-323

ISL XC-320, XC-323

Novell Ethernet_802.2 XC-322

SAP XC-322

IEEE 802.10 XC-339

Novell IPX

configurable encapsulation XC-312

VLANs

formats supported XC-311

encapsulation sde command XC-315, XC-341

encapsulation smds command XC-13

encapsulation types XC-169, XC-217

encryption tunnels XC-95

ESI field and MAC address

in LANE ATM address XC-364

Ethernet XC-216

export target communities XC-149

Index


extended label ATM interface XC-173

extended MPLS ATM port XC-81

external traffic

definition XC-28

enabling TMS collection XC-40

extranet XC-95

F

fair-queue XC-170

fast switching

description XC-4, XC-7, XC-11

disabling

AppleTalk XC-14

DECnet XC-14

IP XC-12

IPX XC-15

VINES XC-14

XNS XC-15

enabling

AppleTalk XC-11

IP XC-12

IPX XC-13

same interface XC-12

enabling for directed broadcast packets

IPX XC-13

ISO CLNS XC-15

SMDS XC-13

AppleTalk XC-13

IP XC-13

IPX XC-13

feature interaction

IPX MLS

restrictions XC-287

Feature Navigator

See platforms, supported

filtering output, show and more commands xxxvi

flow masks

IP multicast MLS XC-256

flows

IP multicast MLS

completely and partially switched XC-257

Forum protocols XC-139

forward equivalence class XC-85

frame processing

MPOA XC-433

Frame Relay XC-95

frame tagging

VLANs XC-309

G

global configuration mode, summary of xxxii

global flow cache XC-139

H

hardware platforms


HDLC

IEEE 802.10 XC-310

headend LVC

definition XC-139

disabling XC-133, XC-139

help command xxxii

holding-time command XC-441

hops XC-162

hosts

communication XC-94

content and web XC-95

hot LSC redundancy

See LSC

hot standby routing XC-121

HSRP (Hot Standby Router Protocol)

group attributes

customizing XC-319

over ISL encapsulation

Index



over ISL encapsulation, configuring XC-319


hybrid networks XC-96

hybrid switching environments

extending VLAN topology XC-312

I

IBGP session XC-150

IEEE 802.10

AppleTalk

encapsulation XC-339

connectivity between VLANs XC-310

description XC-310

encapsulation XC-309, XC-340

HDLS serial interface XC-310

standard XC-339

IEEE 802.1Q

egress rules XC-305

encapsulation

BPDU reception XC-308

BPDU transmission XC-308

forwarding rules between ports XC-305

ingress rules XC-305

restrictions XC-343

IGP destinations

neighbor autonomous systems, finding XC-32

IGP route label XC-107

import target communities XC-149

indexes, master xxvi

ingress edge device XC-427

ingress label switching router XC-167

ingress label switching router, function XC-112

input interface, configuring the rate limit XC-168

interautonomous systems, definition XC-103

interface atm command XC-434, XC-441, XC-446

ILMI PVCs and signaling, setting up XC-368, XC-373 to XC-376

interface ATM for multi-VC mode, configuration (example) XC-217

interface command XC-66, XC-68, XC-315, XC-319, XC-320, XC-322, XC-323, XC-325, XC-326, XC-327, XC-328, XC-341, XC-345, XC-346, XC-347, XC-434

interface configuration mode, summary of xxxii

interface fastethernet command XC-347, XC-348

interface POS3/0/0 XC-215

internal traffic

definition XC-28

TMS collection, enabling XC-40

Internet XC-94

internodal BPX connections XC-137

interprovider VPNs

definition XC-104

inter-VLAN communication XC-304

intranet XC-95

IP

addresses XC-96, XC-162

defining XC-319

enabled state XC-215

fast switching

disabling XC-12

enabling XC-12

flow cache XC-68

inter-VLAN communication XC-312

multicast XC-95

packets XC-110, XC-111, XC-162

classifying XC-165, XC-166

setting XC-113

precedence XC-162

assignments XC-218

setting XC-218

route cache invalidation, controlling XC-15

subnets, defining XC-319


unnumbered XC-169

ip address command XC-319

ip cache-invalidate-delay command XC-16

ip cef accounting command XC-40

Index


ip cef command XC-37, XC-145, XC-172

ip cef load-sharing algorithm original command XC-39

ip cef load-sharing algorithm tunnel command XC-39

ip cef load-sharing algorithm universal command XC-39

ip cef table consistency-check command XC-47

ip flow-aggregation cache destination-prefix command XC-70

ip flow-aggregation cache prefix command XC-70

ip flow-aggregation cache source-prefix command XC-70

ip flow-cache entries command XC-67

ip flow-export command XC-67, XC-69

ip load-sharing per-packet command XC-39

ip mroute-cache command XC-299

IP multicast MLS

complex sample network topology (figure) XC-281

components XC-255

configuration (example) XC-278, XC-280

configuring and monitoring XC-275

enabling XC-276

flow mask XC-256

flows

completely and partially switched XC-257

forwarding table XC-255

Layer 2 forwarding table XC-255

Layer 3 MLS cache XC-255

Layer 3 switching information, displaying XC-277

management interface XC-277

MLSP XC-277

packet rewrite XC-256

PIM, enabling XC-276

prerequisites XC-273

restrictions

access lists XC-275

external routers XC-275

routers XC-274


source-destination-vlan flow mask XC-256

topologies XC-253

IP multicast routing

MDS


description XC-298

global enabling XC-299

interface, enabling on an XC-299

interface status, displaying XC-300

line card packet counts, clearing XC-299

line card packet counts, displaying XC-300

MFIB table, clearing XC-299

MFIB table, displaying XC-300

MFIB table summary, displaying XC-300

packet statistics, displaying XC-300

switched packet counts, displaying XC-300

switched packet counts, displaying XC-300

ip multicast-routing command XC-299

IP precedence, setting XC-218

ip route-cache cef command XC-37

ip route-cache command XC-12, XC-13, XC-299

ip route-cache distributed command XC-68, XC-325

ip route-cache flow command XC-66, XC-68

ip route-cache same-interface command XC-12

ip routing command XC-325

IP routing over IEEE 802.1Q in VLANs


IPX

configurable encapsulation formats XC-321


encapsulation

SAP XC-322

encapsulation formats

Ethernet V2 XC-321

Novell-ether XC-321

Subnetwork Access Protocol (SNAP) XC-321

fast switching

directed broadcast packets, enabling XC-13

disabling XC-15

enabling XC-13

ISLs, routing over XC-321

padding packets XC-18

Index


route cache

invalidation XC-17

size XC-16

SAP XC-322


VLANs

TRISL, configuring XC-323

TRISL, configuring NetWare XC-323

ipx broadcast-fastswitching command XC-13

IPX MLS

access lists

overview XC-261

access lists, configuration (example) XC-295

cache XC-258

components XC-258

MLSP XC-258

MLS-RP XC-258

MLS-SE XC-258

NFFC XC-258configuration task list XC-285

flow mask modes XC-259

destination XC-259

destination-source XC-259

flows XC-258

IPX MLS on interface, enabling XC-289

management interface

router, specifying on XC-289

management interface, specifying XC-289

MLSP on router, enabling XC-288

monitoring and maintaining XC-290

operation XC-292

packet rewrite XC-259

prerequisites XC-285

restrictions XC-286

feature interaction XC-287

guidelines XC-286

maximum transmission unit size XC-287

sample network topology (figure) XC-261, XC-291

VLAN ID to interface, assigning XC-288

VTP domain interface, adding XC-288

VTP domain interface, adding (caution) XC-288

ipx network encapsulation command XC-322, XC-323, XC-347

ipx pad-process-switched-packets command XC-18

ipx route-cache command XC-13, XC-15, XC-18

ipx route-cache inactivity-timeout command XC-17

ipx route-cache max-size command XC-17

ipx routing command XC-322, XC-323, XC-347

IPX routing over ISL in VLANs

IPX routing, enabling XC-322

NetWare

subinterface, configuring XC-322

VLAN encapsulation format XC-322

IS-IS (Intermediate System-to-Intermediate System) XC-120

transitioning an IS-IS network to a new technology XC-90

ISL (Inter-Switch Link Protocol)

Banyan VINES encapsulation XC-316

DECnet

encapsulation, configuring XC-316

description XC-310


configuration tasks XC-314

frame tagging XC-313

HSRP VLAN encapsulation XC-319

IPX encapsulations XC-321

link XC-310

overview XC-313

subinterface, configuring on a XC-325

VLANs

identifier XC-313

traffic, distributed on VIP card XC-324

XNS encapsulation XC-325, XC-326, XC-327

ISO CLNS

fast switching XC-15

Index


K

keepalive-lifetime command XC-441

keepalive-time command XC-441

L

label

assigning XC-111

disposition XC-139

imposition XC-139

switch routers XC-162

label binding XC-85

distribution XC-85

label edge device XC-116

label forwarding XC-161

label space XC-116

label switching

destination prefixes, configuring XC-144

incremental enabling XC-143

paths, configuring XC-144

restrictions XC-80

routing XC-85

subset of destination prefixes, enabling XC-144

label switching network

router-only XC-142

label switching router, configuring XC-166

LAN

segmentation XC-303

LANE (LAN emulation)

address resolution XC-357

assigning components to subinterfaces

rules XC-366

ATM address

constructing XC-364

ESI field XC-364

ESI values derived from MAC address XC-365

prefix, configuring on a switch XC-364, XC-367

syntax XC-364

templates XC-365

wildcards XC-365values of wildcard characters XC-365

broadcast-and-unknown server (BUS) XC-361

Cisco’s implementation XC-355

client XC-355, XC-361

and server, setting up XC-375 to XC-376

changing to different emulated LAN, change database first XC-375

MAC address XC-364

protocol address, assigning XC-375, XC-376

requires MAC address XC-363

components XC-355

subinterfaces, rules for assigning XC-366

unique ATM address XC-363

configuration plan and worksheet recommended XC-367

configuration server XC-355

ATM address, locally configured XC-368

database XC-355

enabling XC-373

how clients find XC-356

on major interface XC-366

configuration task list XC-366

database

default LAN, setting up XC-370

restricted-membership LANs, setting up XC-372

setting up XC-370

task list for, setting up XC-370, XC-408

types of entries XC-355

unrestricted-membership LANs, setting up XC-371

default emulated LAN, unrestricted membership mandatory XC-370

emulated LANs

and subnetworks XC-375, XC-376

default, setting up database for XC-370

default components on several routers, configuration (example) XC-383, XC-384

multiple (figure) XC-385

names, unique on an interface XC-355

Index


emulated LANs, routing between XC-355, XC-359, XC-374, XC-375

ESI template XC-365

Ethernet support XC-362

fault tolerance XC-354

interaction with MPOA XC-429

LE ARP XC-361

MAC address

clients on a given interface XC-363

MAC layer connectivity XC-354

MPOA XC-377

multicast addresses XC-357

network flappage XC-380

prefix template XC-365

scenarios

multiple emulated LANs XC-359

single emulated LAN XC-358

typical XC-358

server XC-361

and clients, setting up XC-374 to XC-376

brief description XC-355

Cisco’s implementation XC-355

single emulated LAN scenario (figure) XC-358

SSRP XC-362, XC-377

support

Banyan Vines XC-362

DECnet XC-362

XNS XC-362

supported routing protocol XC-362

token ring

configuring for MPOA XC-445

VCCs

Configure Direct (server) XC-356

Control Direct XC-356, XC-357

Control Distribute XC-357

Data Direct XC-356, XC-357

Multicast Forward XC-357

Multicast Send XC-357

types (figure) XC-356

VCC types XC-356

lane auto-config-atm-address command XC-374

lane client command XC-375, XC-376

lane client flush command XC-376

lane client mpoa client command XC-446

lane client mpoa client name command XC-434

lane client mpoa server command XC-446

lane client mpoa server name command XC-441

lane client tokenring command XC-446

lane config command XC-373

lane database command XC-370 to XC-372, XC-408, XC-410, XC-411, XC-446

lane server-bus command XC-375, XC-440

lane server-bus ethernet command XC-434

lane server-bus tokenring elan-id command XC-446

LANs (local area network)

segmentation XC-303

with VLANs XC-312

Layer 2

addresses XC-7

encapsulating interfaces XC-312

forwarding table


Layer 3

addresses XC-7

building VPNs XC-95

connectionless architecture XC-95

features XC-111

MLS cache


LC-ATM ports XC-115

LCN (logical channel number), configuring XC-125

LDP

definition XC-81

hot redundancy, configuring XC-126

LE ARP XC-361

LECs

commands XC-446

database, configuring XC-446

Index


Token Ring, configuring XC-446

LERs XC-111, XC-215

LES XC-354

LES/BUS, configuring XC-446

LFIB

maintaining in autonomous systems XC-106

load balancing

in VLANs XC-312

loopback XC-216

loopback addresses, configuring XC-138

low-latency service class XC-95

LSC (label switch controller)

configuring XC-222, XC-223, XC-230, XC-231, XC-242, XC-243

definition of XC-113

external interface XC-114

functional description XC-113


preventing from acting as an edge LSR XC-128

redundancy

ATM switches, configuring XC-125

benefits XC-122

definition XC-122

failover XC-130

hot redundancy, configuring XC-126, XC-129

hot to warm, switching from XC-122

incorporating XC-119

standalone LSC, migrating from XC-123

supported distribution protocols XC-120

supported routing protocols XC-120

VSI, configuring XC-125

warm redundancy, configuring XC-127, XC-129

LSPs, preventing creation of XC-130

LSR (label switch router) XC-111

configuring XC-162

definition XC-113


network configuration XC-221

LVC

establishing XC-138

headend XC-139

PVP, configuring XC-174

tailend XC-138

M

mask destination command XC-70

mask source command XC-70

master control port, ATM XC-115, XC-139

maximum burst size XC-216

migration path XC-96

MLS

access lists XC-252, XC-262

cache XC-248

candidate packet XC-250

CAR

restrictions XC-263

configuration (examples) XC-269

configuring and monitoring XC-265

data encryption

restrictions XC-263

enabler packet XC-251

external routers

usage guidelines XC-248

features XC-249

implementation XC-247

media XC-262

NAT

restrictions XC-263

policy route-map

restrictions XC-263

TCP intercept

restrictions XC-263

terminology XC-248

with an extended access list, configuration (example) XC-271

with a standard access list, configuration (example) XC-270

without access lists, configuration (example) XC-269

Index


MLSP

description XC-248

MLS-RP

description XC-248

mls rp ip multicast command XC-276

mls rp ip multicast management-interface command XC-277

mls rp ipx command XC-288, XC-289, XC-290

mls rp locate ipx command XC-290

mls rp management-interface command XC-289, XC-290

mls rp vlan-id command XC-289

mls rp vtp-domain command XC-288, XC-290

MLS-SE

description XC-248

MMLS-RP

interfaces, enabling on XC-276

IP multicast routing, enabling XC-276

overview XC-255

PIM, enabling on interface XC-276

MMLS-SE

overview XC-255

modes

See command modes

modular QoS CLI

function XC-166

ingress label switching router XC-166

more command XC-29

MPC-LEC and MPS-LEC Relationships XC-430

MPLS

architecture XC-113

backbone XC-162


configuring XC-171

destination prefix XC-170

distributed fair queueing, configuring XC-170

forwarding XC-99

functions XC-84

multi-VC mode in MPLS-enabled core, configuring XC-169

multi-VC using cos-map function, configuring XC-170

network XC-110

packets XC-112

PVC in non-MPLS-enabled core, configuring XC-169

sample network topology (figure) XC-142, XC-214

software XC-162

subinterface, creating XC-219

switching and routing features XC-113

traffic engineering, configuring XC-149

verifying configuration XC-175

virtual private network XC-139

VPN


configuration example XC-193

features XC-149

figure XC-101

security XC-95

verifying configuration XC-158

MPLS experimental field

function XC-113

setting XC-165

using XC-111

MPLS LSC

as an edge LSR XC-116

features of XC-113

supported devices XC-114

MPOA (Multiprotocol over ATM)

benefits XC-431

cache imposition reply XC-428

cache-imposition request XC-428

description XC-427, XC-429

ELAN ID, configuring XC-377, XC-434, XC-440

frame processing XC-433

LANE clients XC-377

LANE interaction XC-429

MPC



monitoring XC-435

Index


MPS



monitoring XC-442

network ID XC-440

shortcuts XC-440

virtual circuits XC-431

MPS-NHRP

routing interaction XC-439

resolution reply XC-428

resolution request XC-428


Token Ring


MPC to MPC Shortcut in an IP Routed Environment (figure) XC-447

MPC to MPC Shortcut in an IP SRB-Routed Environment (figure) XC-451

traffic flow XC-429

mpoa client config name command XC-434, XC-435

mpoa client name command XC-434

mpoa server config name command XC-441

mpoa server name command XC-441

mpoa server name trigger ip-address command XC-442

Multicast Forward VCC XC-357

Multicast Send VCC XC-357

multiple LVC model XC-162

multi-VC mode

BPX1 and BPX2 XC-225


edge LSR1 XC-225, XC-226, XC-228, XC-229, XC-234

LSC1 XC-224

LSC2 XC-225

MPLS-enabled core XC-169

N

name elan-id command XC-377, XC-434, XC-440, XC-446

name ELAN preempt command XC-380

name local-seg-id command XC-370 to XC-373, XC-446

name server-atm-address command XC-370 to XC-373, XC-408, XC-410, XC-411, XC-446

NAT (Network Address Translation)

MLS

restrictions XC-263

native VLAN ID XC-307

NBMA (nonbroadcast multiaccess) network XC-427

NDE (NetFlow Data Export), configuring XC-269

NDIS-compliant LAN drivers

with ATM LANE XC-310

NetFlow XC-65, XC-68

accounting benefits XC-65

cache XC-67

customizing number of entries XC-67


configuring XC-66

description XC-65

destination-prefix aggregation


minimum mask, configuring XC-70

exporting cache entries XC-67, XC-69

exporting information to network management applications XC-67

free-flow queue XC-67

identifying packet flows XC-65

IP

flow cache XC-68

policy routing XC-63

prefix aggregation



source-prefix aggregation


statistics XC-68

switching

description XC-50

traffic control XC-65

traffic performance XC-65

Index


NetFlow aggregation

minimum mask

default value XC-71

description XC-62

network

changes XC-304, XC-309

commerce XC-94

core XC-95

design XC-309

IPX MLS

topology (figure) XC-261

management XC-304

VlanDirector XC-309

management applications

NetFlow statistics XC-67

monitoring XC-140

performance XC-309

point-to-point overlay XC-95

provider XC-95

scalability XC-309

security XC-309

services

accounting XC-304

QoS XC-304

security filtering XC-304

topology XC-309

network-id command XC-441

networks

hybrid XC-96

switched XC-312

next-hop-self address forwarding XC-109

NFFC (NetFlow Feature Card)

description XC-248

NHRP (Next Hop Resolution Protocol)

resolution reply XC-428

resolution request XC-428

servers XC-429

node configuration XC-137

no ip load-sharing per-destination command XC-38

nonrecursive accounting data

displaying XC-32

enabling XC-40

notes, usage in text xxvii

Novell Ethernet_802.2

encapsulation

formats XC-322

Novell IPX

in VLANs XC-312

VLANs

configurable encapsulation XC-312

NRP (Node Resource Processor)

ATM switch, controlling XC-137

configuring XC-226

faults XC-138

functions XC-134

MPLS, running XC-134

position, displaying XC-173

virtual circuits, configuring XC-135

NSP (Node Switch Processor)

Cisco 6400 UAC, configuring XC-226

functions XC-134

O

ODI-compliant LAN drivers

with ATM LANE XC-310

online documentation, accessing xxviii

OSPF (Open Shortest Path First), LSC redundancy, using XC-120

P

PA-A1 interface (ATM Lite) XC-216

PA-A3 interface XC-217

packet rewrite

IPX MLS XC-259

packets

bandwidth XC-111

Index


classification XC-111

classifying XC-113, XC-166

discard XC-162

forwarding between autonomous systems XC-107

from customer XC-95

from VPN XC-95

IP XC-110

padding for IPX XC-18

prioritizing XC-165

prioritizing for IP XC-165

setting XC-113, XC-165

transmitted XC-110, XC-216

PE (provider edge routers) XC-95

CE routing sessions, configuring to XC-150

function XC-112

PE routing sessions, configuring to XC-150

static route CE routing sessions, configuring to XC-152

peer model XC-95

per-class WFQ XC-163

per-flow WFQ XC-163

performance XC-304, XC-309

per-interface WRED XC-163

per-VC WRED XC-217

PIM (Protocol Independent Multicast), enabling XC-276

platforms, supported

Feature Navigator, identify using xxxvii

release notes, identify using xxxvii

point-to-point

connection maps XC-95

overlay XC-95

WRED XC-216


policy map, configuring XC-167

policy route-map

MLS

restrictions XC-263

port assignments XC-173

ports

master control XC-139

precedence assignments XC-218

precedence bits, function XC-111, XC-113

private

connections XC-95

intranet XC-95

IP addresses XC-96

privileged EXEC mode, summary of xxxii

process switching

description XC-7

prompts, system xxxii

public

IP addresses XC-96

IP network XC-96

PVC (permanent virtual circuits)



in non-MPLS-enabled core, configuring XC-169

mode XC-169

on point-to-point subinterface XC-219

PVP (permanent virtual paths)


LVC, configuring XC-174

value, determining the XC-137

Q

QoS (quality of service) XC-95

ATM interface supported features XC-163

ATM switch supported features XC-164

committed access rate XC-162

configuring XC-164

definition XC-110

description XC-110

function XC-111

mapped functions XC-111

maps XC-170

operation, verifying XC-171

sample network topology XC-214

support XC-226

Index


support on MPLS backbone XC-162

weighted fair queueing XC-162

Weighted Random Early Detection XC-162

question mark (?) command xxxii

queue weight, changing XC-170

R

rate limit XC-216

rate-limit-access list, configuring XC-168

redundancy

between multiple routers XC-318

HSRP XC-318

in VLANs XC-312

LANE XC-354

release notes


resolution reply

MPOA XC-428

NHRP XC-428

resolution request

MPOA XC-428

NHRP XC-428

resources

sharing between VLANs XC-312

RIP (Routing Information Protocol)

parameters XC-151

ROM monitor mode, summary of xxxii

route

distribution XC-312

processing XC-312

route cache

invalidation, controlling XC-15, XC-17

size XC-16

switching decision XC-4

route maps XC-149

routers

architecture XC-5

as MPOA servers XC-433

in switched VLANs XC-312

label switching, enabling XC-80

packet headers, analyzing XC-84

PE XC-95

redundancy XC-121

route target communities XC-149

routing

between VLANs XC-312

decisions XC-5

processes XC-5, XC-6

routing protocols XC-120, XC-161

for hot redundancy XC-127

for warm redundancy XC-127

RSM/VIP2 (Route Switch Module/Versatile Interface Processor 2) XC-430

RSVP (Resource Reservation Protocol) XC-85

S

SAID (Security Association Identifier)

IEEE 802.10 XC-339

scalability XC-94, XC-95

in VLANs XC-309

security XC-309

filtering XC-304

VLANs XC-304

security levels XC-95

segmentation XC-302, XC-303

with VLANs XC-312

service class XC-95

service provider backbone XC-139

set configserver command XC-369

set ip next-hop verify-availability command XC-72

shortcut-frame-count command XC-435

shortcut-frame-time command XC-435

shortcut VCC XC-428, XC-433

show adjacency command XC-46

show cef command XC-46

show cef interface command XC-46

Index


show cef linecard command XC-46

show interface stats command XC-300

show ip cache command XC-16

show ip cache flow aggregation destination-prefix command XC-71

show ip cache flow aggregation prefix command XC-71

show ip cache flow aggregation source-prefix command XC-71

show ip cache flow command XC-68

show ip cef adjacency command XC-46

show ip cef command XC-32, XC-46

show ip cef events command XC-46

show ip cef exact-route command XC-46

show ip cef inconsistency command XC-47

show ip cef summary command XC-181

show ip cef traffic prefix-length command XC-46

show ip interfaces command XC-46

show ip mcache command XC-300

show ip mds forwarding command XC-300

show ip mds interface command XC-300

show ip mds stats command XC-300

show ip mds summary command XC-300

show ip pim interface count command XC-300

show ip route profile command XC-43

show lane bus command XC-381

show lane client command XC-381

show lane command XC-381, XC-382, XC-434

show lane config command XC-382

show lane database command XC-382

show lane default-atm-addresses command XC-368, XC-382

show lane le-arp command XC-382

show lane server command XC-382

show mls rp ip multicast command XC-277

show mls rp ipx command XC-289, XC-290

show mls rp vtp-domain XC-290

show mpoa client cache command XC-435

show mpoa client command XC-435

show mpoa client statistics command XC-435

show mpoa default-atm-addresses command XC-435, XC-442

show mpoa server cache command XC-442

show mpoa server command XC-442

show mpoa server statistics command XC-442

show route-map ipc command XC-72

show vlans command XC-328, XC-341, XC-348

Simple LANE Service Replication

backup servers XC-354

redundancy requirements XC-377

SMDS (Switch Multimegabit Data Service)

fast switching

AppleTalk XC-13

configuring XC-13

IP XC-13

IPX XC-13

source-route transparent bridging

TR-LANE support XC-362

SPF computation XC-87

spoofing XC-95

SRB (source-route bridging)

TR-LANE


TR-LANE support XC-362

SSRP (Simple Server Redundancy Protocol), configuring XC-368

standby authentication command XC-320

standby ip command XC-319

standby preempt command XC-319

standby priority command XC-319

standby timers command XC-319

standby track command XC-320

static route PE to CE routing sessions, configuring XC-152

statistics

NetFlow accounting XC-68

subautonomous systems

communicating between XC-109

PE router addresses, distributing XC-159

subnets

Index


IP

defining XC-319

supporting documents and resources xxvi

switching

distributed XC-4, XC-68

fast XC-7

description XC-4

ISL VLAN traffic XC-324

next-hop destination XC-5

next-hop determination XC-6

overview XC-4

paths XC-4, XC-7, XC-11

processes XC-4, XC-5, XC-6, XC-7

route caching XC-4

VIP distributed XC-68, XC-324

enabling XC-325

switch redundancy XC-121

T

Tab key, command completion xxxii

tag-switching atm disable-headend-vc command XC-139

tag-switching atm vp-tunnel command XC-118

tailend LVC XC-138

tail -end nodes XC-88

TCP/IP XC-94

TCP Intercept

MLS

restrictions XC-263

TDP (Tag Distribution Protocol)

defined XC-85

definition XC-81

establishing VCI table entries XC-84

with LSC redundancy XC-120

telephony services XC-94, XC-95

TLVs

migrating from old style to new style XC-91

tmasinfo file XC-32

tmstats_ascii file XC-30

tmstats_binary file XC-32

Token Ring

LANE

configuring for MPOA XC-445

MPOA


MPC to MPC Shortcut in an IP Routed Environment (figure) XC-447

MPC to MPC Shortcut in an IP SRB-Routed Environment (figure) XC-451

Token Ring MPOA

MPC to MPC Shortcut In an IP Routed Environment (figure) XC-447

ToS (type of service) XC-170, XC-218

traffic

broadcast XC-304

controlling patterns XC-309

control with NetFlow XC-65

performance XC-65

traffic engineering XC-84


interface configuration to support RSVP-based tunnel signaling and IGP flooding XC-147

IS-IS for MPLS traffic engineering, configuring XC-147

MPLS traffic engineering tunnel, configuring XC-148

OSPF for MPLS traffic engineering, configuring XC-148

tasks XC-146, XC-164

tunnel support, configuring XC-146

traffic flow

MPOA XC-429

traffic patterns XC-96

translation

in VLANs XC-312

TRISL (Token Ring Inter-Switch Link)

enabling XC-320


IP

routing XC-320

Index


IPX XC-322


RIF


TrBRF VLANs


TRISL and Ethernet VLANs


TRISL VLAN and Token Ring


TR LANE (Token Ring LAN emulation)

APPN XC-362

HSRP XC-362

IP XC-362

IPX XC-362

TR-LANE (Token Ring LAN emulation)

AppleTalk XC-362

Banyan Vines XC-362

benefits XC-361

Cisco LightStream 100 XC-363

Cisco LightStream 1010 XC-363

DECnet XC-362

hardware requirements XC-363

software version XC-363

source-route transparent bridging XC-362

SRB XC-362


XNS XC-362

troubleshooting XC-176

tunnels XC-95

mapping traffic into tunnels XC-87

U

user EXEC mode, summary of xxxii

V

VCCs XC-427, XC-433

VCC types

(figure) XC-356

video conferencing XC-95

VINES

fast switching

disabling XC-14

vines metric command XC-316

vines route-cache command XC-14

vines routing command XC-316

VIP

distributed switching XC-68

between ISL VLANs XC-325, XC-337

enabling XC-325

ISL encapsulation XC-325

ISL VLAN traffic XC-324, XC-336

routing decisions XC-4


VLAN configuration (example) XC-337

virtual channel identifier

table entries, establishing XC-84

virtual circuits XC-169

configuring for the 6400 UAC XC-135

configuring more than one XC-224

creating different control VCs XC-125

determining the default control VC XC-137

reducing the number XC-129

virtual paths

defining more than one XC-137

for edge LSRs XC-137

for internodal BPX connections XC-137

virtual trunks

bandwidth XC-117, XC-118


definition XC-116

redundancy, adding XC-126

VLANs

Index


addressing XC-312

AppleTalk

over IEEE 802.10 encapsulation XC-339

routing XC-339, XC-340

subinterface customization XC-340

AppleTalk over ISL encapsulation XC-314

AppleTalk Phase II support XC-312

Banyan VINES over ISL encapsulation XC-316

Banyan VINES support XC-312

broadcast domain XC-302

colors XC-309

communication between XC-304, XC-309

connecting Fast Ethernet devices XC-310

DECnet over ISL encapsulation XC-316

DECnet support XC-312

description XC-302

designing switched VLANs XC-312

encapsulation format XC-341

EtherType XC-306

frame tagging XC-309

hybrid switching environments XC-312

identifier XC-309

IEEE 802.10 encapsulation XC-309

IEEE 802.1Q encapsulation

BPDU reception XC-308

BPDU transmission XC-308

egress rules XC-305

forwarding rules between ports XC-305

ingress rules XC-305

restrictions XC-343

IEEE 802.3 encapsulation XC-306

interoperability XC-311

IP XC-312, XC-320

IP routing over IEEE 802.1Q


IPX XC-323

ISL encapsulation XC-309

isolation between XC-304

LAN segmentation XC-312

Layer 2 translation XC-309

Layer 3 routing XC-309

load balancing XC-312

native VLAN ID XC-307

network

changes XC-309

design XC-309

management XC-304

performance, accounting

QoS XC-304Novell IPX encapsulation XC-312

packets traversing shared backbone XC-314

performance XC-309

PVID

description

redundancy in XC-312

routers in XC-312

routing between XC-312, XC-336

routing Novell IPX XC-321


security XC-304, XC-309

segmenting LANs with XC-302, XC-303

sharing resources between XC-312

supported VLAN encapsulation formats XC-311

translation XC-312

VlanDirector XC-309

VLAN ID XC-306

native XC-307

VLAN identifier in IEEE 802.10 encapsulation XC-339

XNS over ISL encapsulation XC-325, XC-326, XC-327

XNS support XC-312

VPI (virtual path identifier)

in virtual trunks XC-116

range XC-173

setting XC-118

VPN (Virtual Private Network) XC-114

connection-oriented XC-95

defining XC-149

IBGP distribution XC-99

Index


label XC-95

multiple XC-95

operation, verifying XC-161

packets XC-95

partitioned routes XC-95

route label XC-107

routes XC-95

exchanging between autonomous systems XC-159

exchanging between sub-autonomous systems in a confederation XC-159

partitioning XC-95

route target communities XC-99

solutions XC-94

traffic XC-95

VRF table XC-161

VSI (Virtual Switch Interface)

Cisco 6400 UAC, configuring for XC-135

control interface XC-175

LSC redundancy, configuring for XC-125

protocol XC-173

session, displaying XC-175

VTP domain

IPX MLS

adding VTP domain interface XC-288

W

warm standby routing XC-121

web hosting XC-95

WFQ (weighted fair queueing)


wildcards

LANE address templates XC-365

WRED (Weighted Random Early Detection)


for congestion avoidance XC-111

function XC-111

point-to-point XC-216

X

XNS (Xerox Network Systems)

fast switching XC-15

in VLANs XC-312

LANE support XC-362

over ISL encapsulation XC-325, XC-326, XC-327


xns network command XC-326, XC-328

xns route-cache command XC-15

xns routing command XC-326, XC-327, XC-328

XTagATM

bandwidth, specifying XC-125

definition XC-115