This document summarizes a study on IP over WDM networks. It discusses the motivations for using IP over WDM due to the exponential growth of IP traffic exceeding voice traffic. WDM technology allows multiple wavelengths on a single fiber, providing a good match for high capacity IP traffic needs. The document also covers IP traffic over WDM networks, MPLS approaches for IP over WDM including GMPLS control planes, and optical internetworking and signaling across network boundaries.

1. 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
2

3. Motivation for IP over WDM
Worldwide Network Demand
30000 •The volume of the Data traffic exceeds the
25000
20000
Voice traffic.
Data
Gb/s
15000
Voice
10000
5000
•Long Haul Optical network follows
0
1996 1997 1998 1999 2000 2001 2002
SONET/SDH transmission standard
Year with time fame of 125 μ sec.
Reference 14: Acute need to increase the data bandwidth
• 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
Reference 16: Exponential Growth of Internet 3

4. Motivation for IP over WDM Continued..
.
Inflexibility in bandwidth granularity
Access ring
National Ring
• Each traffic source must use a fixed
multiple of OC1 (51.84 Mbps) rate,
for example, OC-3 (155Mbps),
ADM
OC-12 (622Mbps), OC-48
(2.4Gbps), and OC-192 (9.9Gbps).
SDH-DWDM
Metro ring
High overhead
• SONET frame require a minimum of
PBX
3% overhead for framing, status
Regional ring OLT
monitoring, and management.
OLT
PBX
• Other Protocol overhead, Here
IP Over PPP over SDH
How present network look like.
4

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 2, Page 14 5
Reference 15, Ch 1, Page 2 Thousand fold capacity enhancement for Submarine cable system
Introduction of high capacity WDM

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)
6

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 7

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
WRS Switch and IP router.
• Nodes are connected by fiber to form physical
topology
Wave length Routed Network • Any two IP router will be connected by all-
λ1 Optical WDM Channel called light path
λ1,λ2, λ3,λ4
λ1,λ2, λ3,λ4
λ2 • The set of lightpath termed as Virtual topology.
λ1,λ2, λ3,λ4 λ1,λ2, λ3,λ4 • Multihop approach
λ1,λ2, λ3,λ4 λ3 λ1,λ2, λ3,λ4
λ4 8
Reconfigurable Wavelength Routing node
Reference 17

9. IP/WDM network Model
IP NCM
• IP Routers are Network element of IP
Layer
• WXC, WADM are Network element
WDM NCM
WRS
of WDM Layer
• Overlay model: IP layer and optical
IP NCM layer are managed and controlled
independently
Over Lay Model
• IP-NCM, WDM-NCM, UNI
• Integrated IP/WDM: Functionality of
both IP and WDM are integrated at
WRS each node.
+ control
Reference 18:Ch 9, Page 347-351 9
Integrated Model

10. Optical Packet switching
• Large gap between IP route
Header
Sync Header Guard Payload Payload
Guard processing and the capacity of
Sync
WDM because of
• Format of an optical Packet • Electrically Store and
• Header encoded at lower speed forwarding technique
• Payload duration is fixed
• Payload Variable bit rate up to 10 Gb/s
• Header and payload at the same wavelength • One possibility is packet
• Guard time to take care of delay variation
• Sync bit used for packet synch
switching in optical domain
Demux Mux
instead of electrical domain
• Statistical Multiplexing
Signal
• Hardware cost
FDL Synchronizer Switching
Fabric
Regenerator • Premature state
O/E O/E • Other Possible solutions in
Header Payload Switch Payload
electrical domain are
Delineation Position Control
Unit
Delineation
– Fast lookup
– Parallelism of the forwarding
Header
Header
Recovery
updating – Label switching Technique
A Generic Optical Packet switching node structure
Reference 18:Ch 9, Page 365-366 10
Reference 19,20

11. Optical Burst Switching
Core Router
Edge Router Access
Network
Access
• It Combines the advantages of
Network
OCS and OPS
Access
Network
• No buffering and Electronic
Processing
λ0
Control Channel
λ1 • High bandwidth utilization
Data Channel 1
λ2
Data Channel 2 • Burst is aggregating a no of IP
λ1 λ1
λ0 λ1 λ2
λ2
FDL
λ0 λ1 λ2 datagram destined for same
Fiber 1 FDL λ2
Optical egress router in the ingress
Switching λ0
λ1 FDL
Network λ1
router
λ0 λ1 λ2 λ2 λ0 λ1 λ2
λ2 FDL
Fiber 2
Demux
Mux
• Control burst and Data Burst
λ0 Control
IM OM
Burst λ0
λ0
IM Processing OM • Node Architecture
Buffer
Optical Burst Switching node Routing
And
Architecture
Table
Scheduler Reference 18:Ch 9, Page 351-355 11
Reference 21

12. MPLS approach in WDM network
IP network
MPLS Network
WRS
IP network
MPLS Back bone for IP network
IP Over MPLS Over WDM
• 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
Reference 22,23 12

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 13

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 14

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
15
Reference 1, Ch 9, page 151

16. Types of MPLS nodes
• Ingress LSR:
– User Traffic classifies into FEC.
– It generate MPLS header and
Ingress
assign it an initial label. LSR
– If QOS is implemented then LSR
will condition the traffic
Transit
LSR
• Transit LSR
– Uses the MPLS header for
forwarding decision
– It also performs label swapping
– Not concerned with IP header Egress
LSR
• Egress LSR
– It removes MPLS header The MPLS nodes
16
Reference 1, Ch 9, page 152

17. Label Distribution and Binding
• MPLS control plane perform the followings:
– Advertising a range of Label values that that an LSR want to use.
– Advertising of those IP address which are associated with Labels
– Advertising of QOS performance parameter and suggested routes
• Label Distribution Protocol (LDP) developed for MPLS by IETF
• Constraint based LDP ( CR-LDP) is an extension of LDP which emulates
circuit switched networks and also support Traffic Engineering operations.
• RSVP Path and RESV message of RSVP-TE(extension of RSVP) also
support Label binding and distributions.
• Extension to BGP is also another method.
• Generalized MPLS extended the RSVP and and LDP for optical
network.
17
Reference 1, Ch 9, page 153

18. Label swapping and Traffic forwarding
• LSR forwarding table map the IP
Incoming Label and interface to
L3
an Outgoing Label and interface. 3 Destination Network
IP
el st
Lab ue
q
Re
• An LSR may explicitly request a
IP L2
Request
Label binding for an FEC from
Label 2
the next hop.
• Ingress LSR analyzes the FEC
l 1
L1
Re
abe
IP
field and correlate the FEC with
que
L
st
a Label, encapsulate the
datagram. Source network
IP
• The Transit LSR process only
label header based on the LSR Label allocation and MPLS forwarding
forwarding table.
18
Reference 1, Ch 9, Page 154 and Reference 2, Ch 5, Page 151

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. Customer 1
Customer 1
IP 33 34 IP 33 35
• This concept allows certain Label to be IP 32 34 IP 32 35
processed by the node while others are ignored. IP 31 IP 31 34 IP 31 35 IP 31
• VPN backbone can accommodate all traffic with one Customer 2 LSR A LSR C Cust 2
set of Labels for the LSP in the back bone. LSR B
IP 32 VPN IP 32
• The customers Labels are pushed down and are IP 33
not examined in the through the MPLS tunnel. IP 33
Customer 3
Customer 3
• When the packet arrive at the end of the VPN
backbone LSP then the LSR pops the Labels. Label Stacking in VPN
• Assumptions:
– Customers at the same ends of the MPLS
end to end path.
– Customers have the same QOS
requirements and FEC parameters Reference 1, Ch 9, page 155
19

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 20

21. MPLS Traffic Engineering Continued…
• Trunks:Aggregation of Traffic flow of the same class which are place
inside an LSP
• MPLS TE concerns with mapping of Traffic trunk on to physical
links of a network through Label switched path.
• MPLS TE is getting extended from Label switched path (LSP) to
Optical switched path( OSP) for 3rd generation Transport network.
• LDP,CR-LDP, RSVP-TE and OSPF (Extension) have been developed
to provide signaling capabilities for MPLS.
21

22. Multi Protocol Lambda switching (MPλS)
• MPλS is the framework for inter working
Optical networks and MPLS.
Label Mgt
MPLS Control Plane
• MPLS and Optical network both have LSP
control plane to Manage the user traffic. Cross Connect table
λ Mgt
• MPLS Control Plane deals with Label Optical Control Plane
distribution and binding an end to end OSP
LSP Cross Connect Table
• The MPLS and Optical Control Plane
Optical Control Plane deals with setting
up wavelength, optical coding scheme
(SDH/SONET), transfer rates, Protection
switching options.
WDM
• Reference 3 and 4 discussed about network
adapting the MPLS TE Control Plane for MPLS network
optical Cross Connect.
MPLS network over WDM network
Reference 1, Ch 9, page 158 22

23. Relationship of OXC and LSR operations
Label Switch Router Optical Cross Connect Sending Receiving
(LSR) (OXC) Node Node
Data Transfer Label Swapping Connect optical Channel USER USER
operation to transfer of one Input port to an
labeled packet from an Output port MPLS MPLS
Input port to an Output
port Optical Optical
Control Plane Discovery,distribute Discovery,distribute and
and maintain relevant maintain relevant state
state information information related with
related with MPLS. optical Transport
network (OTN) MPLS and Optical network Layered model
Forwarding Forwarding Forwarding information
information information Label is is implied in the data
appended with Data Channel.
Packet
Storage of Input - output relation Input - output relation is
switching is maintained in Next maintained by
information hop label forwarding Wavelength forwarding
entry (NHLFE) information base
Reference 1, Ch 9, page 159 23

24. MPLS and MPλS Correlation
MPLS MPλS
Map Label to User
Wavelength
Key aspect Label Value Optical Wavelength Ingress
LSR/OXC
Ingress Node Role of Ingress Node on MPLS Label is Process
the user Traffic, termed correlated with λ
as Ingress LSR appropriate wavelength,
termed as LSR/OXC Transit
PXC
Core node Termed as Transit LSR Termed as Transit PXC,
used to process the
wavelength to make the Map wavelength
routing decisions. User to Label
Egress
Path Termed as Label switch Termed as Optical LSR/OXC
Path (LSP) switched path(OSP)
Processing of user Traffic in the MPλS
Reference 1, Ch 9, page 160 24

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 25

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 26

27. IP, MPLS and Optical Control Plane
• 3rd Generation transport networks
encompasses three Control plane. IP Control Plane
(Routing Layer)
• All the above control plane need to be
Data Plane
coordinated to take the benefit of the (Forwarding)
Mapping of
followings: IP Address
to MPLS Label
– Route discovery of IP control Plane MPLS Control Plane
• Routing protocol advertises and discover (Binding Layer)
address as well as routes
– Traffic Engineering capability of MPLS Data Plane
control plane Mapping of (Forwarding)
• MPLS Label distribution protocol will bind MPLS Label
the IP address with Label to wavelength
– Forwarding speed of optical data plane
Optical Control Plane
• MPLS Label will be mapped with (λ Mapping Layer)
wavelength
• Optical node can perform PXC –based
O/O/O operation Data Plane
(λ Mapping Layer)
• O/E/O based Label label swapping will not
be needed. Label
• Ideally same wavelength can be used on User Payload IP Header Header
each OSP segment.
Inter working of three Control Plane 27
Reference 1, Ch 10, page 170

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
Control Control
• Soft permanent optical channel by NMS Control
using network generated signaling and
routing protocol
• Switched Optical Channel which can be
setup by customer on demand using
signaling and Routing protocol Data
• The Optical Node consist of OXC and OXC OXC
Optical network control plane Optical Network Node Optical Network Node
• Between two neighboring node there is pre
configured control channel which may In Optical Node Model
band or Out of band.
• Switching function is done by OXC but it is
based on how cross connect table is
configured
Reference 1, Ch 10, page 169 and Reference 6, Ch 14, page 427 28

29. A Frame work for IP Over Optical
• Optical network control plane should utilize IP based protocol for dynamic
provisioning and restoration of light path with in and across Optical sub-
network
• Two general model discussed in Reference 7.
Unified Service model:
• IP and Optical Network are treated as a single integrated network from a control plane
view.
• Edge router can create a lightpath with specified attributes, or delete and modify lightpath
• When a router are attached to a single optical network. A remote router could compute
an end to end path across the optical internetwork.
• Once lightpath is established forwarding adjacency between the router is developed.
Domain Services model:
• Standardized signaling like RSVP-TE or LDP across the UNI is used
for the following four services: LightPath creation, Lightpath deletion, Lightpath
modification and Lightpath status enquiry
• The protocol for neighbor and service discovery are separate like LMP
29
Reference 1, Ch 10, page 173-174

30. Interconnections for IP over Optical
• Transport of IP datagram over optical network
Peer model
• Single control plane runs over over both IP and Optical domain
• Common routing protocol like OSPF or IS-IS with appropriate
extension can be used for the distribution of topology information
• Opaque LSA for OSPF and Extended TLV for IS-IS can be used.
Overlay model
• Supported by Optical domain service interconnect (ODSI)
• IP domain routing, topology distribution and signaling protocol are
independent of Optical domain routing, topology distribution and
signaling protocol
• Interconnection between signaling and routing are accomplished
UNI defined procedures.
Augmented model
• Separate routing instances in the IP and Optical domains but
information from one routing instances is passed through the other
routing instances.
30
Reference 1, Ch 10, page 175

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:
4. Packet switch capable (PXC): Process traffic based on packet/cell/frame boundaries
5. Time division Multiplex capable (TDM): Process Traffic based on a TDM boundary,
such as SONET/SDH node.
6. Lambda-switch capable (LSC): Process traffic based on the Optical wavelength
7. Fiber switch capable (FSC): Process traffic based on the physical interface.
31
Reference 1, Ch 10, page 177

32. Generalized MPLS use in optical network continued…
• GMPLS = Extension of MPLS to support various
switching technology (RFC 3945)
Packet LSP
• Following switching technology is considered: Layer 2 LSP
• Packet switching: Forwarding capability packet based, IP Router Time slot LSP
• Layer2 switching: Forwarding data on cell or frame: Ethernet, ATM
• TDM or Time slot switching: Forwarding data based on time slot: λ- LSP
SONET,DCS, ADM
• Lambda switching: Performed by OXC
• Fiber switching: Performed by Fiber switch capable OXC Fiber LSP
• GMPLS control plane focus on full range of switching
technology
• Natural Hierarchy of Label stacking in GMPLS:
GMPLS Label stacking LSP
Packet LSP over Layer 2 LSP over over Time slot LSP over λ-
switching LSP over Fiber switching LSP
32
Reference 26, 27

33. GMPLS Control Plane
• Optical network is
becoming the Transport
network for IP traffic Routing protocol
(IP over Optical) Resource discovery and dissemination
CSPF path computation
Wave length Assignment
• IP centric optical control
plane is the best choice
Restoration
Signaling
Management
• GMPLS control plane for
Optical network contains
Routing, Signaling and
Restoration Management GMPLS Control Plane for Optical Network
33
Reference 6, Ch 14, page 428

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.
34
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
35

36. Wavelength Assignment
Fiber 1 Fiber 1
• Wave length Continuity constrained for λ1 λ1
λ2
Transparent OXC λ3
λ2
λ3
λ1
• Opaque OXC and wave length λ2
λ1
λ2
Conversion λ3 λ3
Fiber 2
Fiber 2
Transparent OXC
• Wave Length Assignment Problem is
constrained to the CSPF algorithm λ1
λ2
λ1
λ2
λ3 λ3
• Wave length assignment λ4 λ4
• At the Source λ5 λ5
λ6
λ6
• Random wave length assignment Fiber 1
Fiber 1
Opaque OXC
• Dynamic wavelength
Reservation 1
Reference 6, Ch14, Page 430
Reference 24,25 3
2 36
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
37
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 DST
• Light Path Setup: SETUP, SETUP ACK,
SRC INT_A INT_B
SETUP NAK
• Light Path commitment Phase: ABORT
• Light Path Teardown : TEARDOWN and SETUP
TEARDOWN ACK
SETUP
• Addressing Issue due to High no of entity in SETUP
Optical network: Unique IP to OXC and
other resources through Selector
• Each node will Maintain a Light Path table SETIP ACK
Time
to record the Lightpath ID, Incoming/ Out SETIP ACK
going Port no, SRLG so on..
SETIP ACK
38
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.
39
Reference 6, Ch14, Page 435-436

40. GMPLS Traffic Engineering Extension
• MPLS-TE has two metrics:
• Regular link metric: used in traditional IP routing
• Traffic Engineering link metric: used for constrained based routing
• GMPLS Traffic Engineering Link is Logical Link with Traffic Engineering
properties.
• The Management of Traffic Engineering link is conducted by LMP
• For GMPLS LSP may be taken as TE link but routing adjacency need not to
be established directly between the two end node of the LSP
• For GMPLS link bundle can be advertised as TE link
Reference 6, Ch14, Page 436 40

41. GMPLS Adjacencies
• Three types of adjacencies:
• Routing: Neighbors of the routing protocol
• Signaling: Peering relationship of two nodes established by signaling
• Forwarding:TE link that transit three or more GMPLS nodes in the same instance.
• If Signaling adjacency is established over TE link then
TE link is used as tunnel to establish LSP over it.
Reference 6, Ch14, Page 436-437 41

42. IP – Centric Control Plane
IP Network Receive incoming message
Process the request with the help of other module
Initializing the control Plane
UNI
Optical
Network Main Module (MM)
Resource Protection/
Connection Management Restoration
Module Module Module
(CM) (RMM) (PRM)
•Light Path Signaling
•Maintenance
•Survivability
•Routing and wavelength Assignment (RWA) •Fault Monitoring
•Topology and Resource Discovery •Fast Protection/
•QOS support Restoration
Reference 6, Ch14, Page 461-469 42
Reference 28

43. Connection Module (CM)
IP Network •Connection Request Message Contents
•Light Path ID
•Light Path Type (Primary/ Protection)
UNI •Routing Path
•Assigned wave Length
•QOS type
Optical
Network •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
Light Path ID Status QOS Input Output λ ID
SRC DEST SEQ (Creating/ Type Port Port
NODE NODE NUM Reserved/
ID ID Active/
ID ID
Deleted)
43

44. Connection Module (CM) Continued……
1 Reserved
Creating
5
Processing of Lightpath signaling
4 2
6
Resource Reservation/
Lightpath State Transfer Deleted Active
Release
3
Determination of Input/ Output port
QOS= Protection Sensitive
from the LT
NAK If it is Primary Path and wavelength status “ available”
change the status to “ Used Preemptible”
QOS = best Effort
If Assigned wavelength is available If it is Protection LightPath and wavelength status “ available”
Set the wavelength status Set the status to” Reserved”
“ Used Preemptible”
Else Check the SRLG list
QOS = Mission Critical
If Assigned Wavelength is available 1. Protection Path: Reservation Ack
Change the status to to “ Used and Non-perrmptible” 2. Failure on Primary path
3. Tear Down abort
Else abort the existing lightpath on this wavelength. Then 4. NAK
Change the status to to “ Used and Non-perrmptible” 5. Primary Path : Setup ACK44
6. Tear Down Abort

45. Resource Management Module
• Functionality: Resource Discovery, IP Network
Maintenance, QOS support, RWA
• Neighbor discovery mechanism by sending
UNI
Hello Message on all out going link.
• Local Connectivity Vector (LCV): Store the Optical
cost of the Adjacent Node. Network
• If LCV is updated , it is broadcasted to the
network
• Local resource availability stored in Local
Port Peering λ1 status λ2 status …
Resource Table (LRT) Node
no
• “λi status” indicate state of ith wavelength in ID
the fiber attached to the port λ1 SRLG list λ2 SRLG list
• 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)
Local Resource Table (LRT) 45

46. Resource Management Module Continued….
• Each node build its own Topology
Optical
connectivity Matrix (TCM) with N Network
nodes.
• Each row of TCM is the LCV of the Node Node Node Node Node Node
node I plus a time stamp. 1 2 3 4 5 6
Node
1
• RMM also maintain a Global Resource
Node
Table (GRT) consisting of LRT of all 2
nodes. Node
3
• RMM utilize different RWA algorithm Node
to support QOS. 4
Node
5
• QOS support:
Node
• Best-effort service
6
• Mission critical service
• Protection Sensitive Matrix Topology Connectivity Matrix 46

47. Protection and Restoration Module
• Functions: Setup Co-ordination of Primary and
protection Light Path, Fault detection,
and notification. Connection Request
NAK/ACK
• Fault can be detected by as follows:
• Low level impairments
• Higher layer link probing Control Plane of Node A Control Plane of Node A
• Failure can happen for Control Plane or OXC. (MM) (MM)
• Failure indication Signal (FIS) send to the
source node. (CM) (RMM) (PRM) (CM) (RMM) (PRM)
• If Qos requirement is Restoration the
restoration Path will be calculated. Control
Control Control
• If Qos requirement is Protection then source
node will invoke the setup signal for the
Lightpath previously reserved. Data
OXC OXC
• For Mission critical destination node detect the
failure of the primary Lightpath and turn to Optical Network Node A Optical Network Node B
protection path.
47

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 NNI
• 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 NNI
• 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
48
boundary.

49. Signaling across NNI
Reference 6, Ch14, Page 459-461
ESP ESP ESP ESP
ISP
ISP ISP ISP ISP ISP
ISP
ESP ESP ESP ESP
ISP
ISP ISP
ISP ISP ISP ISP
ISP ESP ESP ESP
ESP ISP
ISP ISP ISP ISP
ISP
ISP ESP ESP ESP ESP
ISP ISP
ISP ISP ISP ISP
ISP ESP ESP ESP ESP 49
ISP ISP
ISP ISP ISP ISP

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.
50

51. References
1. Optical Networks, Third Generation Transport Systems by Uyless Black
2. Optical Network Control Architecture, Protocols, and Standards by Greg Bernstein
• M u lt ip r o t o c o l L a m b d a S w it c h in g : C o m b in in g M P L S T r a f f ic
E n g i n e e r i n g C o n t r o l w i t h O p t i c a l C r o s s c o n n e c t s b y Da n ie l
A wd u c h e , M o v a z Ne t wo r k s Y a k o v R e k h t e r , J u n ip e r Ne t wo r k s ,
IEEE Communications Magazine • March 2001
• Multi-Protocol Lambda Switching: Combining MPLS Traffic Engineering
Control With Optical Crossconnects draft-awduche-mpls-te-optical-03.txt
5. C o n s id e r a t io n s o n t h e d e v e l o p me n t o f a n Op t ic a l C o n t r o l
P l a n e , I n t e r n e t Dr a f t
Do c u me n t : d r a f t - f r e e l a n d - o c t r l - c o n s - 0 1 .t x t b y I P -
Op t ic a l W o r k in g Gr o u p
• I P Ov e r W DM : B u il d in g t h e n e x t Ge n e r a t io n Op t ic a l
I n t e r n e t , E d it e d b y S u d h ir Dix it
• I P o v e r Op t ic a l Ne t wo r k s : A F r a me wo r k : d r a f t - ie t f - ip o -
f r a me wo r k - 0 0 .t x t b y B a l a R a j a g o p a l a n
15. Generalized MPLS - Signaling Functional Description: draft-ietf-mpls- 51
generalized-signaling-05.txt by Network Working Group

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
52

53. Reference Continued….
22. On IP-over-WDM Integration, IEEE Communications Magazine • March 2000
• Labeled Optical Burst Switching for I P-over-W DM Integration, IEEE Communications Magazine
September 2000
• Efficient Distributed Control Protocols for WDM All-Optical Networks*Computer Communications and
Networks, 1997. Proceedings
• Lightpath Communications: An Approach to High Bandwidth Optical WDM’s by Imrich
Chlamtac, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 40, NO. 7. JULY 1992
• Generalized Multiprotocol Label Switching: An Overview of Routing and Management
Enhancements, IEEE Communications Magazine • January 2001
• Generalized Multi-Protocol Label Switching (GMPLS) Architecture, RFC 3945
• On an IP-Centric Optical Control Plane, IEEE Communications Magazine September 2001
53