ABSTRACT
This chapter investigates a path protection design problem-based alternate routing for all-optical wavelength-routed wavelength division multiplexing (WDM) networks. We develop a generic formulation for the so-called shared alternate-path protection (SAPP) problem, which uses alternate-path routing for both primary and protection lightpaths, deals with single failure as well as multiple simultaneous failures, and considers the shared risk link group (SRLG) constraint and multiple practical optimization objectives. The formulated problem is an integer programming problem, which is NP-hard. Therefore it is not practical to have exact solutions, especially under multiple contradictory optimization criteria. For this reason, we use heuristics to obtain approximate optimal solutions and propose a survivable alternate routing (SAR) algorithm based on a kth shortest-path routing algorithm and a genetic algorithm. We assume wavelength converters available at each network node and approximately divide the optimization process into two relatively independent stages: candidate primary and protection route computation, and survivable lightpath routing. Through simulation experiments, we show the effectiveness of SAR in solving the SAPP problem and compare the solutions obtained from SAR with those from using a path protection scheme based on shortest-path routing.
