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

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

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. …

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

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

Large scale example

Large scale example

Large scale example

Large scale example

Large scale example

Large scale example

Large scale example

Large scale example

Large scale example

SMART vs. Tabu Search (1) Random (2‑node‑connected) 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 f-lattice (2‑node‑connected) Physical topology: f-lattice, f = 0…0.35

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

SMART vs. Tabu Search (3)

SMART vs. Simple Layout Algorithm (1) Random (2‑node‑connected) 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! f-lattice (2‑node‑connected) Logical topology: random graphs of average degree 4 Physical topology: f-lattice, f = 0…0.35

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

SMART vs. Simple Layout Algorithm (3)

Applications of SMART 1) Single-link failures 2) Span failures 3) Node failures 4) Double-link failures

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

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

Thank you!

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

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

Double-link failures (3)