Constrained shortest path first algorithm for lambda-switched mesh optical networks with logical overlay OCh/SP rings

We describe a constrained shortest path first (CSPF) routing algorithm for lambda-switched optical networks with logical overlay OCh/SP rings. Speed is definitely a requirement if the algorithm is to be used for lambda-switching, but several features of the network architecture complicate the routing problem. The algorithm we present in this paper meets the requirement of being fast. Moreover, the routing of a lightpath is based on a limited amount of link state information, which can be disseminated by a lightweight routing protocol. Our numerical results show that the performance of the algorithm does not improve significantly if the routing decisions are based on more detailed information about the configuration of the network.