Routing and wavelength assignment for permanent and reliable wavelength paths in WDM networks

We tackle the routing and wavelength assignment problem for wavelength division multiplexing (WDM) networks containing permanent and reliable wavelength paths (WPs). It consists of finding the routes and the wavelength assignment for the normal state of the network and for the important failure scenarios. These scenarios might be the most probable failure scenarios or simply the failure scenarios of interest to the network planner (e.g., the single link failure scenarios). We propose an integer mathematical programming model for this problem. This model supposes that the routing is based on a weighted shortest path policy. From the implementation simplicity and the network performance standpoint, this type of routing is the best one. In order to find solutions, a greedy heuristic is proposed. This heuristic first finds the routing of the permanent and reliable WPs in the normal state of the network and assign heuristically wavelength to WPs. Next, the failure scenarios are treated separately. Finally, a detailed example is presented.