Reconfiguration with no service disruption in multifiber WDM networks based on Lagrangean decomposition

In a WDM based network, lightpaths are established between router pairs to form a virtual topology residing on top of the underlying physical topology. The ability to reconfigure its virtual topology upon dynamically changing traffic patterns has been identified as one of the most important features of WDM based networks. Compared to previously reported reconfiguration studies, we provide contributions along two different directions. First, we address the problem of finding the new virtual topology that maximizes the number of successfully established lightpaths, while guaranteeing absolutely no service disruptions. Second, based on a Lagrangean decomposition approach, we demonstrate that optimal and near-optimal virtual topologies can be obtained by considering only one wavelength in the formulation, leading to a reconfiguration algorithm that scales to an arbitrarily large number of wavelengths. Computational results confirm the high efficiency of the proposed algorithm.