Controlling Campus Device Access Configuring IP Multicast

© 1999, Cisco Systems, Inc. 10-1

Chapter 10

Controlling Campus Device Access

Chapter 10Configuring IP MulticastConfiguring IP Multicast

© 1999, Cisco Systems, Inc. 10-1

© 1999, Cisco Systems, Inc. www.cisco.com BCMSN—10-2

Objectives

Upon completion of this chapter, you will be able to perform the following tasks:• Configure the primary distribution multilayer

switch to forward multicast traffic using the PIM DM protocol• Configure the primary distribution multilayer

switch to forward multicast traffic using the PIM SM protocol• Enable CGMP on the RSM and distribution layer

switch


Configuring IP Multicast

In this chapter, we discuss the following topics:

• Planning for multicast• Configuring multicast services• Enhancing the route processor• Enabling CGMP



In this section, we discuss the following topics:• Planning for Multicast—Planning for Multicast—Configuring IP Multicast Routing—Multicast Routing Protocol Types—Outgoing Interface Lists

• Configuring Multicast Services• Enhancing the Route Processor• Enabling CGMP


Switch Block

Planning Multicast

Core

Video Servers Host

IP Protocol Stack Supporting

Multicast

IP Protocol Stack Supporting

Multicast

IP Multicast Application

IP Multicast Application

NIC Card

Server Block Core Block

Access Switch

Distribution Switch

Distribution Switch

• All entities involved must be capable of identifying and supporting multicast traffic


End-to-End IP Multicast

• IP multicast routing protocols, Protocol Independent Multicast (PIM)

• Internet Group Management Protocol (IGMP)• Cisco Group Management Protocol (CGMP)

Core

VideoServers

Multicast RoutingProtocols (PIM)

Channel 1

Channel 2

Channel 3

CGMP

IGMPMBONE(DVMRP) 1

3

2


Enabling IP Multicast Routing

Router(config#ip multicast routing

Router>enableRouter#show running-configBuilding configuration...Current configuration:!hostname Router!!ip multicast-routing

• Enabling IP multicast routing allows the Cisco IOS software to forward multicast packets


Dense Mode

Receiver 1

B

E

A D F

Source

C

Receiver 2

No Receivers

• Floods everywhere initially• Prunes back where no group members• Prunes on redundant non-shortest path• Induces periodic reflooding


VLAN 45VLAN 43

Outgoing Interface Lists (Oilists)

Flood to all interfaces

First packet source (*,G)

VLAN 42

(*, 224.2.239.61), 00:29:21/00:02:59, RP 0.0.0.0, flags: DJC Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Vlan42, Forward/Dense, 00:07:01/00:00:00 Vlan43, Forward/Dense, 00:29:07/00:00:00 Vlan45, Forward/Dense, 00:29:07/00:00:00171.68.162.29/32, 224.2.239.61), 00:08:06/00:02:59, flags: CT Incoming interface: Vlan45, RPF nbr 172.16.51.3 Outgoing interface list: Vlan42, Forward/Dense, 00:07:02/00:00:00 Vlan43, Forward/Dense, 00:07:02/00:00:00(172.16.42.3/32, 224.2.239.61), 00:15:09/00:02:28, flags: PCT Incoming interface: Vlan42, RPF nbr 0.0.0.0 Outgoing interface list: Null

Subsequent packet source (S,G)

Flood all MC-enabled interfaces except the incoming interface

172.16.42.3

Prune Flag

Prune Statement


Sparse Mode

• No one receives group traffic until a specific join• Rendezvous point queried• Sites pruned back permanently as needed• No periodic flooding as in dense-mode

Receiver 1

B

E

A D F

Source 1

C

Non-Viewer

Non-Viewers

Rendezvous Point


Sparse Mode Oilist

(*,G) Entry

RP IP AddressSparse Mode Join

Flag Set

Outgoing Interfaces

Incoming Interface

Prune Flag Is Set

(*, 224.2.253.119), 3d03h/00:02:59, RP 172.16.53.3, flags: SJC Incoming interface: null, RPF nbr 0.0.0.0 Outgoing interface list: FastEthernet0/0, Forward/Sparse, 1d21h/00:02:13

(172.16.53.1, 224.2.253.119), 00:02:55/00:00:04, flags: PCT Incoming interface: FastEthernet0/0, RPF nbr 0.0.0.0 Outgoing interface list: Null

Indicates this router Is the RP

FA 0/0172.15.53.3

172.15.53.1

Source

Group G



In this section, we discuss the following topics:• Planning for Multicast• Configuring Multicast Services— Configuring a PIM Interface— Choosing and displaying a PIM neighbor— Configuring a Rendezvous Point— Defining the scope of delivery

• Enhancing the Route Processor• Enabling CGMP


Configuring a PIM interface

Router(config)#interface vlan41Router(config-if)#ip pim sparse-dense

Router>enableRouter#show running-confighostname Router!ip multicast-routing(text deleted)interface Vlan101 ip address 172.16.1.41 255.255.0.0 ip pim sparse-dense-mode

• The multicast routing protocol must be specifically assigned to an interface


Verifying the PIM Interface Configuration

RSM144#show ip pim interface

Address Interface Mode Nbr Query DR Count Intvl172.16.1.144 Vlan1 Sparse-Dense 1 30 172.16.1.145172.16.41.144 Vlan41 Sparse-Dense 1 30 172.16.11.145172.16.42.144 Vlan42 Sparse-Dense 0 30 172.16.12.145172.16.43.144 Vlan43 Sparse-Dense 1 30 172.16.13.145172.16.44.144 Vlan44 Sparse-Dense 1 30 172.16.14.145172.16.51.144 Vlan51 Sparse-Dense 4 30 172.16.51.145172.16.52.144 Vlan52 Sparse-Dense 4 30 172.16.52.145

• The show ip pim interface command displays information about interfaces configured for PIM


Selecting a Designated Router 172.16.41.144PIM Router 2

Highest IP AddressElected as DR

PIM Query

172.16.41.143PIM Router 1

• PIM queries are multicast to the all-routers (224.0.0.2) multicast group address periodically (Default = 30 seconds)

• If the DR times-out, a new DR is elected

PIM Query


Selecting a Designated Router (cont.)

Designated Router

• Only the designated router sends host query messages on a LAN

• All PIM routers on a single subnet receive replies from the host

Host Query

Host Reply

PIMRouter


Displaying the PIM Neighbor Table

RSM145>show ip pim neighborPIM Neighbor TableNeighbor Address Interface Uptime Expires Mode

172.16.51.143 FastEthernet1/0 2d02h 00:01:08 v1 Sparse-Dense172.16.51.144 FastEthernet1/0 3d01h 00:01:24 v1 Sparse-Dense (DR)172.16.51.143 FastEthernet1/0 3d01h 00:01:02 v1 Sparse-Dense172.16.51.144 FastEthernet1/0 3d01h 00:01:19 v1 Sparse-Dense172.16.52.143 FastEthernet2/0 2d02h 00:01:08 v1 Sparse-Dense172.16.52.144 FastEthernet2/0 3d01h 00:01:24 v1 Sparse-Dense (DR)172.16.52.143 FastEthernet2/0 3d01h 00:01:02 v1 Sparse-Dense172.16.52.144 FastEthernet2/0 3d01h 00:01:19 v1 Sparse-Dense

• The PIM neighbor table can be used to display the neighboring routers for a specific router


Configuring a Rendezvous Point

Router144(config)#ip pim rp-address 176.16.36.116172.16.31.116Rendezvous Point

172.16.41.144Leaf Router

CampusNetwork

Router144#show runhostname Router(text deleted)!ip classlessip pim rp-address 176.16.31.116

Leaf Router

IPTV Server


Auto-RP

CampusNetwork

I would like to be the RP

for Group XYZ.I would like to be the RP

for Group ABC.

RP Mapping AgentRouter A

Router B

Router A is theRP for Group ABC and Router B is

is the RP for Group XYZ.

Designated Router

Designated Router

Designated Router


Configuring send rp-announce

Router(config)#ip pim send-rp-announce vlan101 scope 16

Router#show running-confighostname Router!!ip multicast-routing(text deleted)ip pim rp-address 172.16.1.116ip pim send-rp-announce vlan101 scope 16

• Auto-RP requires an RP announce command on the router


Well-Known Group224.0.1.39

Auto-RP Discovery

RP Mapping Agent

RP Candidate


Designated Router

rp-announceMessage

rp-announceMessage

RP Candidate

rp-discoveryMessage

Designated Router

Designated Router


Designated Router

Designated Router

Designated Router

rp-discoveryMessage


Router#show running-confighostname Router!!ip multicast-routing(text deleted)ip pim rp-address 172.16.1.116ip pim send-rp-discovery scope 16

Configuring send rp-discovery

Router(config)#ip pim send-rp-discovery scope 16

• A router must be explicitly configured as a mapping agent


interface Vlan101 ip address 172.16.1.113 255.255.255.0 ip pim sparse-dense-mode ip multicast ttl-threshold 16

Configuring ttl-threshold

Router(config)#interface vlan101Router(config-if)#ip multicast ttl-threshold 16

• Only multicast packets with a TTL greater than the interface TTL threshold are forwarded on the interface


Displaying the Multicast Routing Table

Host Entry

RSM114#show ip mrouteIP Multicast Routing TableFlags: D - Dense, S - Sparse, C - Connected, L - Local, P - Pruned R - RP-bit set, F - Register flag, T - SPT-bit set, J - Join SPTTimers: Uptime/ExpiresInterface state: Interface, Next-Hop or VCD, State/Mode

(*, 224.2.210.17), 00:30:17/00:02:59, RP 172.16.53.3, flags: SP Incoming interface: Vlan52, RPF nbr 172.16.52.3 Outgoing interface list: Null

(172.16.53.1/32, 224.2.210.17), 00:01:49/00:01:10, flags: PT Incoming interface: Vlan52, RPF nbr 172.16.52.3 Outgoing interface list: Null

(*, 224.0.1.39), 00:29:22/00:02:59, RP 0.0.0.0, flags: SJP Incoming interface: Null, RPF nbr 0.0.0.0 Outgoing interface list: Null

Source Entry


Logging Multicast Packets

Address of the Packet Source

Receiving Interface

Multicast group address

Bytes in the Packet

Action Taken on the Packet

Router#debug ip mpacketIP multicast packets debugging is onRSM114#3d06h : IP: s=172.16.53.1 (Vlan51) d=224.2.210.17 len 60, mforward3d06h : IP: s=172.16.53.1 (Vlan52) d=224.2.210.17 len 60, mforward3d06h : IP: s=172.16.53.1 (Vlan51) d=224.0.1.24 len 65, mforward3d06h : IP: s=172.16.53.1 (Vlan52) d=224.0.1.24 len 65, mforward



In this section, we discuss the following topics:• Planning for Multicast• Configuring Multicast Services• Enhancing the Route Processor— Joining a multicast group—Manipulating the IGMP version

• Enabling CGMP


Joining a Multicast Group

I am a member of Group 224.1.2.3.

I will answer that ping.

RSM144#show ip igmp int vlan41Vlan41 is up, line protocol is up Internet address is 172.16.41.144/24 IGMP is enabled on interface Current IGMP version is 2 (text deleted) Multicast designated router (DR) is 172.16.41.144 (this system) IGMP querying router is 172.16.41.143 Multicast groups joined: 224.0.1.40 224.0.1.39 224.1.2.3

CampusNetwork

Router#ping 224.1.2.3

Type escape sequence to abort.Sending 1, 100-byte ICMP Echos to 224.1.2.3, timeout is 2 seconds:

Reply to request 0 from 172.16.41.143, 1 ms

List of Group Memberships

IP Address of the Interface Servicing the

Group

172.16.41.143


IGMPv2 and IGMPv1 Devices in the Same Subnet

Leave to224.0.0.2

224.1.2.3

IGMPv1 Router

IGMPv1 Host1.2.3.11

I am configured as a IGMPv1 Router. I

will ignore any IGMPv2 leave

messages.

IGMPv1 Host1.2.3.12

IGMPv2 Host1.2.3.13

H3H1 H2

• Mixed-environment routers do not automatically detect the IGMP version of systems on the subnet and dynamically switch between versions


Determining the IGMP Version

Router#show ip igmp interfaceVlan101 is up, line protocol is up Internet address is 172.16.1.113, subnet mask is 255.255.255.0 IGMP is enabled on interface Current IGMP version is 2 CGMP is enabled on interface IGMP query interval is 60 seconds IGMP querier timeout is 120 seconds IGMP max query response time is 10 seconds Inbound IGMP access group is not set Multicast routing is enabled on interface Multicast TTL threshold is 16 Multicast designated router (DR) is 172.16.1.114 IGMP querying router is 172.16.1.113 (this system) Multicast groups joined: 224.0.1.40 224.0.1.39 224.1.2.3


Changing the IGMP Version

Router(config-if)#ip igmp version 1

interface Vlan41 ip address 172.16.411.143 255.255.255.0 ip pim sparse-dense-mode ip multicast ttl-threshold 16 ip igmp version 1

• The IGMP version has a default of 2



In this section, we discuss the following topics:• Planning for Multicast• Configuring Multicast Services• Enhancing the Route Processor• Enabling CGMP— Enabling CGMP on the router— Enabling CGMP on the switch— Enable CGMP Leave


Enabling CGMP on the Router

Router#show run(text deleted)interface Vlan41 mac-address 4004.0114.0011 ip address 172.16.41.144 255.255.255.0 no ip redirects ip pim sparse-mode ip cgmp

CampusNetwork

Router(config-if)#ip cgmp 172.16.41.143

• CGMP is disabled by default• MP can only run on an interface if PIM is configured on the

same interface


CGMP — Joining a Group

0000.0c12.3456

I can reach device 000.0c12.3456 out of Port 2. I will add that port to group 224.1.2.3 in my switch forwarding table.

CGMP Join MAC Address 0000.0c12.3456 to224.1.2.3

0100.0cdd.dddd 0100.0cdd.dddd

I have no knowledge of

device 0000.0c12.3456

I am 0000.0c12.3456. I would like to join

multicast group224.1.2.3

To 224.0.0.2


Enabling CGMP on the Switch

Switch (enable)set cgmp enable

Switch (enable) show config (text deleted)#cgmpset cgmp enableset cgmp leave disable

• By default, CGMP is disabled on the switch


CGMP — Leaving a Group

• If router detects no members left in a multicast group, it sends a CGMP remove to all switches

0000.0c12.3456

I can reach device0000.0c12.3456out of Port 2. I will remove that port from group 224.1.2.3in my switchforwarding table.

CGMP Remove MAC Address 0000.0c12.3456 from224.1.2.3

0100.0cdd.dddd 0100.0cdd.dddd

I have no knowledge of

device 0000.0c12.3456

IGMPLeave to224.0.0.2


Enabling CGMP Leave on the Switch

Switch (enable) set cgmp leave enableCGMP leave processing enabled.

(text deleted)!#cgmpset cgmp enableset cgmp leave enable!

• CGMP leave is disabled by default


Verifying CGMP on the Switch

Switch (enable) show cgmp statistics 41CGMP enabledCGMP statistics for vlan 41:valid rx pkts received 211915invalid rx pkts received 0valid cgmp joins received 211729valid cgmp leaves received 186valid igmp leaves received 0valid igmp queries received 3122igmp gs queries transmitted 0igmp leaves transmitted 0failures to add DSW144 to RTR144 0topology notifications received 80number of CGMP packets dropped 2032227

• CGMP statistics display only the information that has been learned automatically through CGMP


Laboratory Exercise: Visual Objective

A

Multicast StreamGroup 224.2.163.21

B

Multicast StreamGroup 224.2.229.95

Multicast Group 224.2.229.95 Member

Multicast Group 224.2.163.21 Member


Summary

• Cisco multicast switches and routers support the PIM, IGMP, CGMP, and DVMRP protocols.• The DR is responsible for maintaining a current status

of group membership on a LAN. • The mode in which an interface is configured

determines how the routing table is populated and packets are forwarded.• The presence or absence of an RP determines how a

sparse-dense mode interface will react • Auto-RP facilitates the use of multiple RP in a network• CGMP leverages IGMP information to make Layer 2

forwarding decisions.


Review

• Discuss the basic tasks required to set up a multicast session within the network.• Describe the three PIM modes. • Explain how Auto-RP automates the distribution of

group-to-RP mappings in a network.• Discuss how CGMP leverages IGMP information to

facilitate Layer 2 forwarding decisions.

Documents

Controlling Campus Device Access Configuring IP Multicast