Stochastic RWA and Lightpath Rerouting in WDM Networks

In a telecommunication network, Routing and Wavelength Assignment (RWA) is the problem of finding lightpaths for incoming connection requests. When facing dynamic traffic, greedy assignment to requests based on predefined deterministic policies leads fragmented network that cannot make use its full capacity due stranded bandwidth. At this point service providers try recover via defragmentation process. We study setting from two perspectives: (i) while granting RWA (ii) during process by lightpath rerouting. For both problems, we present first two-stage stochastic integer programming model incorporating request uncertainty maximize expected grade service. develop decomposition-based solution approach, which uses various relaxations newly developed problem-specific cut family. Simulation variety instances in rolling-horizon framework 52 stages shows our models provide high-quality solutions compared traditionally used ones. Specifically, proposed provisioning yield improvements up 19% overall 20% spectrum saving, rerouting grant 36% more using just 4% bandwidth spectrum.