Survivable Mapping Algorithm by Ring Trimming (SMART) for large

IP-over-WDM networks

Maciej Kurant, Patrick ThiranSwiss Federal Institute of Technology -

Lausanne (EPFL), Switzerland

BroadNets 2004, October 25-29, San Jose

Survivability

How to deal with failures?

There are several methods• Protection vs restoration• WDM layer vs IP layer

We use only the IP restoration approach:(The failures are detected at the IP layer, and a new route is found dynamically.)

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Connected Link-survivable mapping

We assume unlimited capacities of physical links.

The problem is not new…

[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.

…

[Crochat97]J. Armitage, O. Crochat and J. Y. Le Boudec, “Design of a Survivable WDM Photonic Network,” Proceedings of IEEE INFOCOM 97, April 1997.

Our solution

SMART - Survivable Mapping Algorithm by Ring Trimming

or “by Cycle Contraction”

The SMART algorithm (link-survivability example)

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A single node!

Iteration 1 Iteration 2 Iteration 3

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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)

• Tabu Search is widely used to solve the problem of survivability

• Our Tabu Search implementation followed the one in [Crochat97] Random (2‑node‑connected)

f-lattice (2‑node‑connected)

• Physical topology: f-lattice, f = 0…0.35

• Logical topology: random graphs of average degree 4

SMART vs. Tabu Search (2)

SMART finds a link-survivable mapping 10-30% more often than Tabu97 does.

SMART vs. Tabu Search (3)

(a) Run-times

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SMART

O (N3.5)

O (N2.4)

11 hours

25 sec

Tabu97 run-time SMART run-time

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(b) Y =

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!

Random (2‑node‑connected)

f-lattice (2‑node‑connected)

• Physical topology: f-lattice, f = 0…0.35

• Logical topology: random graphs of average degree 4

SMART vs. Simple Layout Algorithm (2)

Simple Layout Algorithm is about 3 times faster than SMART.

SMART vs. Simple Layout Algorithm (3)

# of topologies mapped by SMART# of topologies mapped by Simple Layout Algorithm

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N - number of vertices

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1) Single-link failures 2) Span failures3) Node failures4) Double-link failures

Applications of SMART

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 (2)

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NSFNETNSFNET3EC

Random graph (3-edge-connected)

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Logical topology:

Physical topology:

Double-link failures (3)

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Average degree of the logical topology

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Shortest Path

SMART

SMART - Double-link failure extension