2. Graceful Label Numbering in Optical MPLS Networks Ibrahim C. Arkut ica@lefke.edu.tr Refik C. Arkut refik.arkut@alcatel.com.tr Nasir Ghani nghani@sorrentonet.com

3. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 2 Multi Protocol Label Switching is a routing technique that imitate connection oriented forwarding method in a connectionless (IP) environment What is MPLS?

4. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 3 Hop-by-hop or source routing to establish labels - non-shortest paths Uses label native to the media Multi level label substitution transport What is MPLS? (cont.)

5. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 4 Why MPLS ? Performance and scalability Explicit routing and traffic engineering –Constraint-based Routing / QoS Separation of control (routing) and forwarding Virtual Private Networks –Controllable tunneling mechanism Unified approach to routing functionality

6. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 5 Best of both Worlds Packet Forwarding Circuit Switching Flexibility and predictability Performance - complexity trade-off MPLS +IP IP ATM HYBRID

7. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 6 over the same path treated in the same manner mapped to the same label IP1 IP2 IP1 IP2 LSR LER (ingress) LER (egress) LSP IP1#L1 IP2#L1 IP1#L2 IP2 #L2 IP1#L3 IP2#L3 Forwarding Equivalence Classes (FEC) Flow of IP packets

8. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 7 FEC / label binding mechanism Binding is done once at the ingress LER / OXC Currently based on destination IP address prefix Future mappings based on SP-defined policy In electronic MPLS domain Label FEC (packet associated) In photonic MPLS domain Label Wavelength ( channel associated)

9. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 8 MPLS Signaling Protocols Hop-by-hop & Explicit Label Distribution Protocol (LDP) Constraint-based Routing LDP (CR-LDP) Extensions to RSVP

10. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 9 Packet Forwarding over LSP- (Label swapping) Label swapping is ‘simple’, but is it simple enough?

11. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 10 Matching the Speeds? For increased speed, the mechanism must be simpler! IP/MPLS Frame Monitoring Optical (Physical) Layer Electronic Speed Optical Speed IP/MPLS-over-WDM

12. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 11 Graceful Numbering of Trees It is a well-known labeling problem in graphs and trees. Number the nodes of a graph G with 1, 2,…, e so that induce edge labels computed by absolute node number differences are all distinct. Notorious conjecture of Ringel- Kotzig [1963] asserts that “all trees are graceful” 3 1 14 2 15 13 4 12 5 11 7 10 6 9 8 5 12 2 6 7 4 8 13 1 9 14 10 3 11 Graceful numbering of a tree

13. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 12 MPLS unicast with graceful numbering

14. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 13 MPLS+Graceful Numbering

15. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 14 MPLS multicast caterpillar using graceful numbering

16. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 15 Graceful numbering of paths and caterpillars (*) are not complex and resembles label assignment in MPLS N-23N-12 6 N N-2 N-1N N-6 5 1 N-5N-44 7N-33 2 1 N-1 N-2 N-3 N-4 N-5 etc. N-1 N-2 N-3 N-4 N-5N-6 N-7 N-8 N-9 N-10 N-11 N-12 N-13 N-14 etc. PATH CATERPILLAR backbone path (*)I. Cahit and R. Cahit, “On Graceful Numbering of Spanning Trees”, Info. Proc. Lett., 3(4), March 1975,

17. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 16 MPLS Roles IP/MPLS:Service and addressing, Quality of service, TE, Protection Sonet:Multiplexing, Protection Optical:Bandwidth MPLS SONET Optical Adaptation MPLS IP/MPLS: Service and addressing Quality of service, TE, Protection, Multiplexing, Optical:Protection, Multiplexing Bandwidth Future Present Efficient logical overlay over Sonet Efficient Peer model and transport topology aware

18. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 17 One Control (MPLS) - End to End IP Packets Cells Frames MPLS Control Plane VPI/VCI /DLCI/ Label Lambda VPI/VCI /DLCI/ Label IP Packets Cells Frames Label

19. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 18 Lambda-Labeling with Graceful Numbering (IP-Over-WDM) ”G - labeling" Optical MPLS Core IP/MPLS network (electronic) Large bandwidth lambda LSP's explicit routing I1 I2 I3 I4 I5 I6 M8 M9 M10 M11 M12 Lambda-labeling approach: multiple MPLS network node types Graceful Lambda (G  Labeling in Optical Core Network

20. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 19 Graceful Numbering of Two Light-paths (without lambda conversion) IF the light-paths from C to B and from A to D arrive to node X with the same label but different wavelengths THEN no need to convert any wavelength at node X

21. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 20 Graceful Numbering of Two Light-paths with wavelength conversion IF the light-path from C to B and from A to D arrive to node X with the same labels and wavelengths THEN one of the wavelength is to be converted at node X

22. OptiComm 2000, October 24, 2000, Dallas, Texas Chart 21 Summary Topology associated labeling Distinct labels per LSP or MC Caterpillar Label conflict resolution by central control Source controlled Graceful Number assignments Labels generation automatic and simple Efficient O(n) algorithms Minimum label-process time Distributed algorithm to assign G -labels