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A study of “IP Over WDM”
Partha Goswami
22/07/05
2
Topics• Motivations for IP over WDM
• IP Traffic Over WDM
• MPLS approch for IP over WDM
• GMPLS Control Plane
• Optical Internetworking and Signaling across Network Boundary
3
Motivation for IP over WDM
Worldwide Network Demand
0
5000
10000
15000
20000
25000
30000
1996 1997 1998 1999 2000 2001 2002
Year
Gb
/s Data
Voice
Reference 14: Acute need to increase the data bandwidth
Reference 16: Exponential Growth of Internet
•The volume of the Data traffic exceeds the Voice traffic.
•Long Haul Optical network follows SONET/SDH transmission standardwith time fame of 125 μ sec.
• Most of the data traffics are due to IP traffic where existing transmission technique in the Fiber backbone is not giving Optimal Multiplexing.
• Several alternative are in Consideration:•IP over Fiber• PPP to replace SONET•Lightweight SONET
4
.
Inflexibility in bandwidth granularity
• Each traffic source must use a fixed multiple of OC1 (51.84 Mbps) rate, for example, OC-3 (155Mbps), OC-12 (622Mbps), OC-48 (2.4Gbps), and OC-192 (9.9Gbps).
High overhead
• SONET frame require a minimum of 3% overhead for framing, status monitoring, and management.
• Other Protocol overhead, HereIP Over PPP over SDH
PBX
SDH-DWDM
OLT
PBXOLT
Access ring
Metro ring
Regional ring
National Ring
ADM
How present network look like.
Motivation for IP over WDM Continued..
5
Motivation for IP over WDM Continued…• Advent of wavelength division multiplexing (WDM) technology that allows multiple
wavelengths on a single fiber, the "IP over fiber" issue takes on a new dimension.
• End stations (traffic sources) and routers (traffic switches) have a choice of wavelengths on which to direct their traffic.
• High capacity of WDM and exponential growth of IP traffic is the perfect match of the need and technology
Reference 15, Ch 1, Page 2Introduction of high capacity WDM
Reference 15, Ch 2, Page 14Thousand fold capacity enhancement for Submarine cable system
6
Challenges of IP over WDM
• IP over WDM domain, attempts to address issues like:• Light path selection and network routing • Support for various classes of service • Algorithms for network restorations and protection scheme• Integration with existing technology• Standardization of Signaling and protocol
• The future optical component technology may allow full optical switching of IP packets.
• The Optical switching can be classified as follows:• Optical Circuit switching (OCS)• Optical Burst Switching (OBS)• Optical Packet Switching (OPS)
7
Three Generation of Digital Transport Network
• First Generation: T1 , E1
• Second Generation : SONET , SDH
• Third Generation : Optical Transport network• Suitable for: Voice, Video, Data, QOS, BOD• Multiplexing and Switching scheme: WDM/O/O/O• Capacity: Tbps• Payload: Fixed or Variable length• Protocol support: PPP, IP, ATM, MPLS• Commercial Availability: Full feature 3rd Generation yet to arrive due to lack of mass scale commercial deployment O/O/O
Reference: 1, Page 1-4
8
IP Traffic Over WDM network• IP Traffic Over WDM is the Correct Choice
for Next Generation Internet backbone.
• OCS technology is matured.
• Network node will use Wavelength Routing Switch and IP router.
• Nodes are connected by fiber to form physical topology
• Any two IP router will be connected by all- Optical WDM Channel called light path
• The set of lightpath termed as Virtual topology.
• Multihop approach
Wave length Routed Network
λ1,λ2, λ3,λ4
λ1,λ2, λ3,λ4
λ1,λ2, λ3,λ4
λ1,λ2, λ3,λ4
λ1,λ2, λ3,λ4
λ1 λ1,λ2, λ3,λ4
λ2
λ3
λ4
WRS
Reconfigurable Wavelength Routing nodeReference 17
9
IP/WDM network Model
• IP Routers are Network element of IP Layer
• WXC, WADM are Network element of WDM Layer
• Overlay model: IP layer and optical layer are managed and controlled independently
• IP-NCM, WDM-NCM, UNI
• Integrated IP/WDM: Functionality of both IP and WDM are integrated at each node.
WRS
WDM NCM
IP NCM
IP NCM
Over Lay Model
WRS+ control
Integrated ModelReference 18:Ch 9, Page 347-351
10
Optical Packet switching• Large gap between IP route
processing and the capacity of WDM because of
• Electrically Store and forwarding technique
• One possibility is packet switching in optical domain instead of electrical domain
• Statistical Multiplexing• Hardware cost• Premature state
• Other Possible solutions in electrical domain are
– Fast lookup
– Parallelism of the forwarding
– Label switching Technique
HeaderSync Header Guard Payload
SyncPayload
Guard
• Format of an optical Packet• Header encoded at lower speed• Payload duration is fixed• Payload Variable bit rate up to 10 Gb/s• Header and payload at the same wavelength• Guard time to take care of delay variation• Sync bit used for packet synch
HeaderDelineation
HeaderupdatingHeader
Recovery
PayloadPosition
Switch Control Unit
PayloadDelineation
O/E O/E
FDL Synchronizer SwitchingFabric
Signal Regenerator
Demux Mux
A Generic Optical Packet switching node structure
Reference 18:Ch 9, Page 365-366Reference 19,20
11
Optical Burst Switching
λ0Control Channel
Data Channel 1
Data Channel 2
λ1
λ2
Fiber 1
Fiber 2
λ0 λ1 λ2
λ0 λ1 λ2
Core Router
Edge Router Access Network
Access Network
Access Network
OpticalSwitchingNetwork
FDL
FDL
FDL
FDL
Control Burst
Processing
RoutingTable
BufferAnd
Scheduler
IM
IM
OM
OMλ0
λ0
λ1
λ1
λ2
λ2 λ2
λ1
λ1
λ2
λ0
λ0
λ0 λ1 λ2
λ0 λ1 λ2
Demux
Mux
Optical Burst Switching node Architecture
• It Combines the advantages of OCS and OPS
• No buffering and Electronic Processing
• High bandwidth utilization
• Burst is aggregating a no of IP datagram destined for same egress router in the ingress router
• Control burst and Data Burst
• Node Architecture
Reference 18:Ch 9, Page 351-355Reference 21
12
MPLS approach in WDM network
• MPLS is the backbone for IP network.
• MPLS approach for OCS is Known as LOCS or MPλS
• MPLS approach is suitable for OBS and OPS using LOBS and LOPS respectively
• If Label of the MPLS is mapped with λ of the WDM network, then IP-MPLS frame work enables direct integration of IP and WDM
IP Over MPLS Over WDM
Reference 22,23
WRS
IP network
IP network
MPLS Network
MPLS Back bone for IP network
13
MPLS and Optical Network
• MPLS is the key components for 3rd generation Transport networks.
• MPLS Architecture is defined in RFC 3031 .
• Operations of Label switch router (LSR), Label assignments, and Label swapping.
• What is label switching and how it is different than traditional internets ?
• Correlations between MPLS label value and optical wavelength
Reference 1, Chapter 9
14
Advantage of Label Switching
• Speed, delay and jitter: Faster than traditional IP forwarding
• Scalability: Large no IP address can be associated with few labels
• Resource consumption: Less resource for control mechanism to establish Label switch Path (LSP)
• Route control: More efficient route control than destination based routing
• Traffic Engineering: Allows network provider to engineer the link and nodes in the network to support different kind of traffic considering different constraints.
• Labels and Lambdas: Wave length can be used for Label and optical router capable of O/O/O can forward the traffic with out any processing delay
Reference 1, Ch 9
15
The forwarding Equivalence Class (FEC)
• What is FEC?– It associates an FEC value with destination address and
a class of traffic.– The class of traffic is associated with a destination
TCP/UDP port no and/or protocol ID field in the IP datagram header.
• Advantages of FEC– Grouping of packet into classes– For different FEC we can set different priorities– Can be used for efficient QOS operation
Reference 1, Ch 9, page 151
16
Types of MPLS nodes
• Ingress LSR: – User Traffic classifies into FEC. – It generate MPLS header and
assign it an initial label.– If QOS is implemented then LSR
will condition the traffic
• Transit LSR– Uses the MPLS header for
forwarding decision– It also performs label swapping– Not concerned with IP header
• Egress LSR– It removes MPLS header
Transit LSR
Ingress LSR
Egress LSR
The MPLS nodes
Reference 1, Ch 9, page 152
18
Label swapping and Traffic forwarding
• LSR forwarding table map the Incoming Label and interface to an Outgoing Label and interface.
• An LSR may explicitly request a Label binding for an FEC from the next hop.
• Ingress LSR analyzes the FEC field and correlate the FEC with a Label, encapsulate the datagram.
• The Transit LSR process only label header based on the LSR forwarding table.
Source network
Destination Network
IP
Reque
st
Reques t
RequestLa
bel
1L
abel
2
IPL1
IPL3
IPL
2
Label
3
Label allocation and MPLS forwarding
Reference 1, Ch 9, Page 154 and Reference 2, Ch 5, Page 151
IP
19
MPLS Support of Virtual Private Network• MPLS can be used to support VPN customers
with very simple arrangement.
• It is possible by label stacking : Placing of more than one Label in the MPLS header.
• This concept allows certain Label to be processed by the node while others are ignored.
• VPN backbone can accommodate all traffic with one set of Labels for the LSP in the back bone.
• The customers Labels are pushed down and are not examined in the through the MPLS tunnel.
• When the packet arrive at the end of the VPN backbone LSP then the LSR pops the Labels.
• Assumptions:
– Customers at the same ends of the MPLS end to end path.
– Customers have the same QOS requirements and FEC parameters
Customer 1
Customer 3
Customer 2
Customer 3
Cust 2
Customer 1
IP 31 IP 31
IP 32 IP 32
IP 33IP 33
IP 31
IP 32
IP 33
LSR A LSR BLSR C
34
34
34
IP 31
IP 32
IP 33
35
35
35
VPN
Label Stacking in VPN
Reference 1, Ch 9, page 155
20
MPLS Traffic Engineering• It deals with Performance of network.
• High performance required for Customer’s QOS need.
• Methodologies are Measurement of Traffic and Control of Traffic.
• RFC 2702 specify the requirement of TE over MPLS.
• Objective of TE are Traffic Oriented and Resource Oriented performance enhancement.
• Traffic oriented performance objective are minimizing Traffic loss, minimizing delay, maximizing throughput and enforcement of SLAs.
• Resource oriented performance objective deals with Communication Links, Routers and Servers.
• Efficient management of the available bandwidth is the essence of TE
Reference 1, Ch 9, page 156-157
22
Multi Protocol Lambda switching (MPλS)• MPλS is the framework for inter working
Optical networks and MPLS.
• MPLS and Optical network both have control plane to Manage the user traffic.
• MPLS Control Plane deals with Label distribution and binding an end to end LSP
• Optical Control Plane deals with setting up wavelength, optical coding scheme (SDH/SONET), transfer rates, Protection switching options.
• Reference 3 and 4 discussed about adapting the MPLS TE Control Plane for optical Cross Connect.
MPLS Control Plane
Optical Control Plane
LSPCross Connect table
OSPCross Connect Table
Label Mgt
λ Mgt
The MPLS and Optical Control Plane
MPLS network
WDM network
MPLS network over WDM network
Reference 1, Ch 9, page 158
23
Relationship of OXC and LSR operations
Label Switch Router
(LSR)
Optical Cross Connect
(OXC)
Data Transfer Label Swapping operation to transfer labeled packet from an Input port to an Output port
Connect optical Channel of one Input port to an Output port
Control Plane Discovery,distribute and maintain relevant state information related with MPLS.
Discovery,distribute and maintain relevant state information related with optical Transport network (OTN)
Forwarding information
Forwarding information Label is appended with Data Packet
Forwarding information is implied in the data Channel.
Storage of switching information
Input - output relation is maintained in Next hop label forwarding entry (NHLFE)
Input - output relation is maintained by Wavelength forwarding information base
USER
MPLS
Optical
USER
MPLS
Optical
Sending Node
Receiving Node
MPLS and Optical network Layered model
Reference 1, Ch 9, page 159
24
MPLS and MPλS Correlation
MPLS MPλS
Key aspect Label Value Optical Wavelength
Ingress Node Role of Ingress Node on the user Traffic, termed as Ingress LSR
MPLS Label is correlated with appropriate wavelength, termed as LSR/OXC
Core node Termed as Transit LSR Termed as Transit PXC, used to process the wavelength to make the routing decisions.
Path Termed as Label switch Path (LSP)
Termed as Optical switched path(OSP)
Transit PXC
Ingress LSR/OXC
Egress LSR/OXC
Map Label to Wavelength
Map wavelength to LabelUser
User
Processλ
Processing of user Traffic in the MPλS
Reference 1, Ch 9, page 160
25
MPLS and Optical TE similarities
• MPLS term Traffic trunk = Optical Layer Term Optical Channel trail
• Attributes of Traffic for MPLS TE:
– Traffic Parameters: Indicate BW requirement of traffic trunk
– Adaptive attributes: Sensitivity and Possibility of re-routing of trunk
– Priority attribute: Priority of path selection and path placement for trunk
– Preemption attribute: Whether a traffic trunk can preempt an existing trunk
– Resilience attribute: Survivability requirement of Traffic trunk
– Resource class affinity attribute: Restrict route selection to specific subset of resources
Reference 1, Ch 9, page 162
26
Possibilities for the MPλS Network
• Following work remain in Reference 4 which needs to be done to complete the MPλS Network:
• Concept of link bundling.
• Distribution of OTN topology , available bandwidth, available channels and other OTN topology state using extension of IS-IS or OSPF
• Exploring the possibilities of fiber termination in the same device which perform the role of OXC and IP router.
• Uniform Control Plane for LSR and PXC as close interaction are needed between Control and Data plane for the interwork of Label and wavelength.
• How to increase the utilization of the optical Channel trail in case traffic in the LSP mapped with Optical channel is low.
Reference 1, Ch 9, page 163-165
27
IP, MPLS and Optical Control Plane• 3rd Generation transport networks
encompasses three Control plane.
• All the above control plane need to be coordinated to take the benefit of the followings:
– Route discovery of IP control Plane• Routing protocol advertises and discover
address as well as routes
– Traffic Engineering capability of MPLS control plane
• MPLS Label distribution protocol will bind the IP address with Label
– Forwarding speed of optical data plane• MPLS Label will be mapped with
wavelength• Optical node can perform PXC –based
O/O/O operation• O/E/O based Label label swapping will not
be needed.• Ideally same wavelength can be used on
each OSP segment.
Reference 1, Ch 10, page 170
IP Control Plane (Routing Layer)
Data Plane(Forwarding)
MPLS Control Plane(Binding Layer)
Data Plane(Forwarding)
Optical Control Plane(λ Mapping Layer)
Data Plane(λ Mapping Layer)
Mapping of IP Address
to MPLS Label
Mapping of MPLS Labelto wavelength
User Payload IP HeaderLabel
Header
Inter working of three Control Plane
28
Optical Control Plane• The requirement of Optical Control Plane as
specified in Reference 5
• Permanent Optical channel setup by NMS by network management protocol
• Soft permanent optical channel by NMS using network generated signaling and routing protocol
• Switched Optical Channel which can be setup by customer on demand using signaling and Routing protocol
• The Optical Node consist of OXC and Optical network control plane
• Between two neighboring node there is pre configured control channel which may In band or Out of band.
• Switching function is done by OXC but it isbased on how cross connect table is configured
Reference 1, Ch 10, page 169 and Reference 6, Ch 14, page 427
OXC
Control
Optical Network Node
OXC
Control
Optical Network Node
Data
Control
Optical Node Model
31
Generalized MPLS use in optical network• Purpose of GMPLS development: (Reference 8)
• To support MPLS operation in optical network with ability to use the optical technologies as
» Time division ( SONET ADM)
» Wavelength
» Spatial switching( Incoming Fiber to out going fiber)
• GMPLS assume that forwarding decision based on time slot , wavelength and physical ports.
• GMPLS Terminology:1. Packet switch capable (PXC): Process traffic based on packet/cell/frame boundaries
2. Time division Multiplex capable (TDM): Process Traffic based on a TDM boundary, such as SONET/SDH node.
3. Lambda-switch capable (LSC): Process traffic based on the Optical wavelength
4. Fiber switch capable (FSC): Process traffic based on the physical interface.
Reference 1, Ch 10, page 177
32
• GMPLS = Extension of MPLS to support various switching technology (RFC 3945)
• Following switching technology is considered:• Packet switching: Forwarding capability packet based, IP Router
• Layer2 switching: Forwarding data on cell or frame: Ethernet, ATM
• TDM or Time slot switching: Forwarding data based on time slot: SONET,DCS, ADM
• Lambda switching: Performed by OXC
• Fiber switching: Performed by Fiber switch capable OXC
• GMPLS control plane focus on full range of switching technology
• Natural Hierarchy of Label stacking in GMPLS:
Packet LSP over Layer 2 LSP over over Time slot LSP over λ-switching LSP over Fiber switching LSP
Generalized MPLS use in optical network continued…
Reference 26, 27
Fiber LSP
λ- LSP
Time slot LSP
Layer 2 LSP
Packet LSP
GMPLS Label stacking LSP
33
GMPLS Control Plane• Optical network is
becoming the Transport network for IP traffic
(IP over Optical)
• IP centric optical control plane is the best choice
• GMPLS control plane for Optical network contains Routing, Signaling and Restoration Management
Reference 6, Ch 14, page 428
Routing protocol
Resource discovery and disseminationCSPF path computation
Wave length Assignment
SignalingRestoration Management
GMPLS Control Plane for Optical Network
34
Resource Discovery and Link-state Information Dissemination
• Each Optical node need to know the Global topology and resource information, which is possible by broadcasting local resource use and
neighbor connectivity information by each optical node.
• It can be done the OSPF (Reference 9) and its extension ( Reference 10)
• It can also be done by IS-IS (Reference 11) and its extension (Reference 12)
• Here neighbor discover require inband communication which is possible for
Opaque OXC with SONET termination.
• For Transparent OXC neighbor discovery generally utilizes a separate protocol such as Link management protocol ( Reference 13)
• Issues: Scalability problem for link addressing and Link state advertisement
• Solutions: • Unnumbered links: Globally unique end node ID ( LSR ID) plus local selector ID
• Link Bundling: The link attribute of multiple wavelength channel of similar characteristics can aggregated.
Reference 6, Ch 14, page 428-429
35
CSPF Path computation
• CSPF = SPF + resource constraint + policy constraint : To achieve the MPLS TE objective RFC 2702
• Such path computation is NP complete and Heurestic have to be used.
• The objective of path computation in optical network is to minimize the resource required for routing light paths for a given SLA.
• For optical network CSPF algorithm needs to be modified for the following reason
• Link Bundling and Restoration Path Computation
• The Solution is Shared Risk Link Group (SRLG): Administrative group associated with some optical Resources that probably share common vulnerability to a Single Failure.
• Example: Fiber in the same conduit can be assigned with one SRLG
36
Wavelength Assignment
• Wave length Continuity constrained for Transparent OXC
• Opaque OXC and wave length Conversion
• Wave Length Assignment Problem is constrained to the CSPF algorithm
• Wave length assignment • At the Source• Random wave length assignment• Dynamic wavelength
Reservation
Reference 6, Ch14, Page 430Reference 24,25
λ1λ2λ3
Fiber 1
λ1λ2λ3
λ1λ2λ3
λ1λ2λ3
Transparent OXC
Fiber 1
Fiber 2Fiber 2
λ1λ2λ3
λ4λ5λ6
λ1λ2λ3
λ4λ5λ6
Opaque OXC
Fiber 1Fiber 1
32
1
Light Path Demand set in a ring
37
Restoration Management• Difference between Optical Layer protection with IP layer MPLS Layer.
• Management and co-ordination among multiple layer is an important issue.
• Optical Protection mechanism can be classified as follows:
• Path Protection
• Link Protection
• Path Protection classified as follows:
• Disjoint Path Protection: 1+1 , 1:1 and M:N
• Link-dependent Path protection
• Restoration Management: Failure detection, Failure notification and Failure restoration.
• Detection by lower layer impairments, higher layer link probing.
• Time for restoration is due to restoration path computation and traffic rerouting from primary path to restoration path
Reference 6, Ch14, Page 431
38
Signaling• Signaling is distributed path establishment
operation across Optical network
• Major Operation of Light Path signaling are Light Path setup, Teardown and Abort
• Light Path Setup: SETUP, SETUP ACK, SETUP NAK
• Light Path commitment Phase: ABORT
• Light Path Teardown : TEARDOWN and TEARDOWN ACK
• Addressing Issue due to High no of entity in Optical network: Unique IP to OXC and other resources through Selector
• Each node will Maintain a Light Path table to record the Lightpath ID, Incoming/ Out going Port no, SRLG so on..
INT_A INT_BSRC
DST
SETUP
SETUP
SETUP
SETIP ACK
SETIP ACK
SETIP ACK
Tim
e
Reference 6, Ch14, Page 432-435
39
GMPLS Signaling Functional Requirements
• Same switching functionality for both end LSR
• GMPLS extends MPLS Signaling in many aspect
• Generalized label is defined with enough flexibility to represent Label for different switching type.
• Label suggestion capability by the upstream node will reduce the LSP setup delay.
• Label set: Upstream restrict the label selection of the down stream to acceptable limit.
• GMPLS support Bi-directional LSP setup.
• Explicit Label label selection offers capability of explicit label selection on a specific on an explicit route
• GMPLS data channel and control channel may be separate.
• GMPLS signaling for fault handling should minimize the packet loss.
Reference 6, Ch14, Page 435-436
42
IP – Centric Control PlaneReceive incoming messageProcess the request with the help of other moduleInitializing the control Plane
OpticalNetwork Main Module
Connection Module
Resource Management
Module(RMM)
Protection/Restoration
Module(PRM)(CM)
(MM)
•Light Path Signaling•Maintenance
•Routing and wavelength Assignment (RWA)•Topology and Resource Discovery•QOS support
•Survivability•Fault Monitoring•Fast Protection/
Restoration
UNI
IP Network
Reference 6, Ch14, Page 461-469Reference 28
43
Connection Module (CM)
OpticalNetwork
UNI
IP Network
Light Path IDSRC DEST SEQ
NODE NODE NUM
ID ID
Status(Creating/
Reserved/
Active/
Deleted)
QOS
Type
Input Output λ ID
Port Port
ID ID
•Connection Request Message Contents•Light Path ID•Light Path Type (Primary/ Protection)•Routing Path•Assigned wave Length•QOS type•SRLG list of Primary Path
•At each hop, request Message is processed•Destination node send ACK along the same path•If there is resource conflict NAK is sent back
44
Connection Module (CM) Continued……
Processing of Lightpath signaling
Resource Reservation/Release Lightpath State Transfer
Determination of Input/ Output port from the LT
If Assigned wavelength is availableSet the wavelength status
“ Used Preemptible”
QOS = best Effort
QOS = Mission CriticalIf Assigned Wavelength is available
Change the status to to “ Used and Non-perrmptible”
Else abort the existing lightpath on this wavelength. ThenChange the status to to “ Used and Non-perrmptible”
QOS= Protection Sensitive
If it is Primary Path and wavelength status “ available”change the status to “ Used Preemptible”
If it is Protection LightPath and wavelength status “ available”Set the status to” Reserved”
Else Check the SRLG list
NAK
Creating
Deleted Active
Reserved1
2
3
45
6
1. Protection Path: Reservation Ack2. Failure on Primary path3. Tear Down abort4. NAK5. Primary Path : Setup ACK6. Tear Down Abort
45
Resource Management Module
• Functionality: Resource Discovery, Maintenance, QOS support, RWA
• Neighbor discovery mechanism by sending Hello Message on all out going link.
• Local Connectivity Vector (LCV): Store the cost of the Adjacent Node.
• If LCV is updated , it is broadcasted to the network
• Local resource availability stored in Local Resource Table (LRT)
• “λi status” indicate state of ith wavelength in the fiber attached to the port
• Possible states are “used and preemptable” , “used and non-preemptable” , “Reserved”, “Available” and “ Faulty”
• “λi SRLG list” stores the SRLG information of the primary path whose protection path has reserved the wavelength (λi status = Reserved)
OpticalNetwork
UNI
IP Network
Port
no
Peering Node ID
λ1 status
λ1 SRLG list
λ2 status
λ2 SRLG list
…
Local Resource Table (LRT)
46
Resource Management Module Continued….
• Each node build its own Topology connectivity Matrix (TCM) with N nodes.
• Each row of TCM is the LCV of the node I plus a time stamp.
• RMM also maintain a Global Resource Table (GRT) consisting of LRT of all nodes.
• RMM utilize different RWA algorithm to support QOS.
• QOS support:• Best-effort service• Mission critical service• Protection Sensitive Matrix
OpticalNetwork
Node 1
Node 2
Node
3
Node
4
Node
5
Node
6
Node 1
Node 2
Node
3
Node
4
Node
5
Node
6
Topology Connectivity Matrix
47
Protection and Restoration Module
• Functions: Setup Co-ordination of Primary and protection Light Path, Fault detection,
and notification.
• Fault can be detected by as follows:• Low level impairments • Higher layer link probing
• Failure can happen for Control Plane or OXC.• Failure indication Signal (FIS) send to the
source node.
• If Qos requirement is Restoration the restoration Path will be calculated.
• If Qos requirement is Protection then source node will invoke the setup signal for the Lightpath previously reserved.
• For Mission critical destination node detect the failure of the primary Lightpath and turn to protection path.
OXC
Control
Optical Network Node A
OXC
Control
Optical Network Node B
Data
Control
(RMM) (PRM)(CM)
(MM)
(RMM) (PRM)(CM)
(MM)
Control Plane of Node A Control Plane of Node A
Connection RequestNAK/ACK
48
Optical Internetworking and Signaling across Network Boundary
• Need for Inter-domain Optical network
• Need for standard• Addressing scheme to identify light path
end points• Routing Protocol• Standard signaling protocol across
Network to Network interface• Restoration procedure• Policies that affect the flow of Control
Information
• Solution is by implementing:• External Signaling Protocol (ESP):
Used for Signaling across NNI• Internal Signaling protocol( ISP): May
be different for different network• Possibility of BGP extension is being studied for
Routing .
• Possibility of CR-LDP or RSVP-TE extension is being studied for Signaling across the network boundary.
NNI
NNI
49
Signaling across NNI
ISPISP ISP
ESP
ISP
ESP
ISP
ISP
ESP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ISP
ESP
ISP
ESP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
ISP
ESP
Reference 6, Ch14, Page 459-461
50
Conclusion• Development and implementation of
GMPSL over the existing technology can only bring the reality of IP over WDM
• Performance of GMPLS in the hybrid scenario should be simulated.
51
References1. Optical Networks, Third Generation Transport Systems by Uyless Black
2. Optical Network Control Architecture, Protocols, and Standards by Greg Bernstein
3. Multiprotocol Lambda Switching:Combining MPLS Traffic Engineering Control with Optical Crossconnects by Daniel Awduche, Movaz NetworksYakov Rekhter, Juniper Networks , IEEE Communications Magazine • March 2001
4. Multi-Protocol Lambda Switching: Combining MPLS Traffic Engineering Control With Optical Crossconnects draft-awduche-mpls-te-optical-03.txt
5. Considerations on the development of an Optical Control Plane, Internet Draft Document: draft-freeland-octrl-cons-01.txt by IP-Optical Working Group
6. IP Over WDM: Building the next Generation Optical Internet, Edited by Sudhir Dixit
7. IP over Optical Networks: A Framework: draft-ietf-ipo-framework-00.txt by Bala Rajagopalan
8. Generalized MPLS - Signaling Functional Description: draft-ietf-mpls-generalized-signaling-05.txt by Network Working Group
9. OSPF Version 2: RFC 2328
52
Reference Continued….10. OSPF Extensions in Support of Generalized MPLS: draft-ietf-ccamp-ospf-gmpls-extensions-00.txt
11. Use of OSI ISIS for Routing in TCP/IP and Dual Environments: RFC 1195
12. IS-IS Extensions in Support of Generalized MPLS: draft-ietf-isis-gmpls-extensions-04.txt
13. Link Management Protocol (LMP) : draft-ietf-ccamp-lmp-10.txt
14. http://www.cs.columbia.edu/~hgs/internet/traffic.html
15. WDM Technologies, Volume III - Optical Networks - 2004 - (By A.K.Dutta)
16. http://bgp.potaroo.net/
17. Design of Logical Topologies for Wavelength-Routed Optical Networks, Rajiv Ramaswami,IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 14, NO. 5, JUNE 1996
18. WDM Optical Networks: Concept, Design and Algorithm by C. Siva Ram Murthy
19. Transparent Optical Packet Switching: The European ACTS KEOPS Project Approach,JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 16, NO. 12, DECEMBER 1998 20. High-capacity Multi-service optical label switching for the next generation Internet,IEEE Optical Communications * May 2004
21. Choices, Features and Issues in Optical Burst Switching, Optical Network Magazine, Vol.1, no.2, pp 36-44, April 2000
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Reference Continued….
22. On IP-over-WDM Integration, IEEE Communications Magazine • March 2000
23. Labeled Optical Burst Switching for I P-over-W DM Integration, IEEE Communications Magazine September 2000
24. Efficient Distributed Control Protocols for WDM All-Optical Networks*Computer Communications and Networks, 1997. Proceedings
25. Lightpath Communications: An Approach to High Bandwidth Optical WDM’s by Imrich Chlamtac, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 40, NO. 7. JULY 1992
26. Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements, IEEE Communications Magazine • January 2001
27. Generalized Multi-Protocol Label Switching (GMPLS) Architecture, RFC 3945
28. On an IP-Centric Optical Control Plane, IEEE Communications Magazine September 2001