Shared path protection based on quality of service in WDM networks

The optimization techniques traditionally used in determining an optimum routing and wavelength assignment (RWA) in a robust WDM network are quite complex, requiring a significant amount of time. For high priority traffic, it is necessary to set up a backup or protection path, whenever a primary path between a source-destination pair is established. We define three classes of service and investigate the problem of optimally allocating resources to the primary and backup (if need) paths. We assume a dynamic lightpath allocation scheme, where a lightpath is established dynamically in response to a request for communication, and is torn down after the communication is over. We propose an efficient mixed integer linear program (MILP) formulation of the problem and show that it can be used for practical-sized networks.