Survivable Mapping Algorithm by Ring Trimming (SMART) for large IP-over-WDM networks

1. BroadNets 2004, October 25-29, San Jose Survivable Mapping Algorithm by Ring Trimming (SMART) for large IP-over-WDM networks Maciej Kurant, Patrick Thiran Swiss Federal Institute of Technology - Lausanne (EPFL), Switzerland

2. Link-survivable mapping Connected Logical topology Mapping We assume unlimited capacities of physical links. GΦ Physical topology Survivability How to deal with failures? There are several methods • Protection vs restoration • WDM layer vs IP layer GL M We use only the IP restoration approach: (The failures are detected at the IP layer, and a new route is found dynamically.)

3. The problem is not new… [Crochat97] J. Armitage, O. Crochat and J. Y. Le Boudec, “Design of a Survivable WDM Photonic Network,” Proceedings of IEEE INFOCOM 97, April 1997. [Sasaki00] G. H. Sasaki and C.-F. Su and D. Blight, “Simple layout algorithms to maintain network connectivity under faults,” Proceedings of the 2000 Annual Allerton Conference. [Modiano02] E. Modiano and A. Narula-Tam, “Survivable lightpath routing: a new approach to the design of WDM-based networks,” IEEE Journal on Selected Areas in Communications, vol. 20, no. 4, 2002 [Giroire03] F. Giroire, A. Nucci, T. Taft, and C. Diot, “Increasing the Robustness of IP Backbones in the Absence of Optical Level Protection,” Proc. of IEEE INFOCOM 2003. [Modiano03] L-W. Chen and E. Modiano, “Efficient Routing and Wavelength Assignment for Recongurable WDM Networks with Wavelength Converters,” Proc. of IEEE INFOCOM 2003. …

4. Our solution SMART - Survivable Mapping Algorithm by Ring Trimming or “by Cycle Contraction”

5. e e e e g g g g g b b b b f f f f f c c c c d a a a a d d d h h h h h Logical topology Mapping GΦ GΦ Physical topology GΦ Iteration 1 Iteration 2 Iteration 3 The SMART algorithm (link-survivability example) Contracted topology GC GC GC e e d A single node! d GL GL GL

6. Large scale example

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15. Random(2‑node‑connected) • f-lattice(2‑node‑connected) SMART vs. Tabu Search (1) • Tabu Search is widely used to solve the problem of survivability • Our Tabu Search implementation followed the one in [Crochat97] • Logical topology: • random graphs of average degree 4 • Physical topology: • f-lattice, f = 0…0.35

16. SMART vs. Tabu Search (2) SMART finds a link-survivable mapping 10-30% more often than Tabu97 does.

17. SMART vs. Tabu Search (3)

18. Random(2‑node‑connected) • f-lattice(2‑node‑connected) SMART vs. Simple Layout Algorithm (1) • Simple Layout Algorithm [Sasaki00], similarly to SMART, breaks down the survivable mapping problem into a set of small and easy to solve subproblems – should be fast! • Logical topology: • random graphs of average degree 4 • Physical topology: • f-lattice, f = 0…0.35

19. SMART vs. Simple Layout Algorithm (2) Simple Layout Algorithm is about 3 times faster than SMART.

20. SMART vs. Simple Layout Algorithm (3)

21. 1) Single-link failures 2) Span failures3) Node failures4) Double-link failures Applications of SMART

22. Double-link failures (1) Idea: Take 3-edge connected structures instead of cycles.

23. Conclusions • SMART is 2-3 orders of magnitude faster than other heristics, and more scalable • SMART works well with many types of failures (single link, span, node and double link) Future work: • Formal analysis of SMART • Introduction of limited capacities of physical links

24. Thank you!

25. Double-link failures(any two links may fail) Application 4

26. Random graph (3-edge-connected) 1 1 NSFNET 10 11 12 13 14 13 11 10 14 12 2 4 9 5 6 3 8 7 7 3 6 5 9 4 2 8 Double-link failures (2) Logical topology: Physical topology: NSFNET3EC

27. Double-link failures (3)