Linear formulation for path shared protection

This paper investigates the problem of optimal diverse routing for shared path-based protection in the complete routing information scenario on mesh optical networks, where a novel Integer Linear Programming (ILP) formulation is introduced such that the least-cost link-disjoint working and protection path-pair can be derived in a single step. The proposed ILP formulation is characterized by the facts that it is solvable with the commercially available Linear Programming (LP) solvers and that it can deal with the dependency between working and spare capacity in the network, which is a step ahead of the most state-of-the-art techniques in the design of diverse routing algorithms for shared protection. To verify the proposed ILP, an experiment is conducted to compare it with four reported schemes for end-to-end shared protection on two network topologies, namely APFPBC, MLR, ITSA, and ILP-2S, where blocking probability is taken as the performance metric with connection requests being dynamically launched into the networks. The simulation results show that the ILP formulation yields the best performance while the ILP-2S scheme investigating less network states yields the worst. We also use the results by the proposed ILP to evaluate the four heuristic-based schemes adopted in the simulation in terms of two performance indexes – the percentage of optimality (denoted as %opti) and the offset of optimality (denoted as Q).