Survivable Paths in Multilayer Networks

TL;DR

This paper introduces new methods for ensuring survivability in multilayer networks by finding sets of paths that can withstand any single link failure, addressing NP-hard problems with ILP formulations and heuristics.

Contribution

It proposes a novel survivability approach for multilayer networks, formulates related optimization problems, and develops algorithms with proven bounds.

Findings

Polynomial-time solutions for restricted path set problems

Heuristics with approximation guarantees for fiber-minimizing sets

Simulation results demonstrating algorithm effectiveness

Abstract

We consider protection problems in multilayer networks. In single-layer networks, a pair of disjoint paths can be used to provide protection for a source-destination pair. However, this approach cannot be directly applied to layered networks where disjoint paths may not always exist. In this paper, we take a new approach which is based on finding a set of paths that may not be disjoint but together will survive any single physical link failure. First, we consider the problem of finding the minimum number of survivable paths. In particular, we focus on two versions of this problem: one where the length of a path is restricted, and the other where the number of paths sharing a fiber is restricted. We prove that in general, finding the minimum survivable path set is NP-hard, whereas both of the restricted versions of the problem can be solved in polynomial time. We formulate the problem as Integer Linear Programs (ILPs), and use these formulations to develop heuristics and approximation algorithms. Next, we consider the problem of finding a set of survivable paths that uses the minimum number of fibers. We show that this problem is NP-hard in general, and develop heuristics and approximation algorithms with provable approximation bounds. Finally, we present simulation results comparing the different algorithms.