Design of wavelength-routed optical networks for circuit switched traffic

We consider the problem of routing and assignment of wavelength (RAW) in wavelength-routed optical networks. Given a set of requests for all-optical connections (or lightpaths), the problem is to find wavelength-continuous routes from the source nodes to their respective destination nodes. Since the number of wavelengths available per link is limited, lightpaths cannot be established between every source-destination node pairs. Moreover, a common wavelength might not be available on all the segments of a chosen route. Thus, routing and wavelength assignment are to be considered concurrently for the best possible performance. Several heuristic algorithms have already been proposed for the RAW problem, however, most of these algorithms are based on the traditional model of circuit-switched networks where the routing and wavelength assignment steps are decoupled. A new RAW scheme is developed which unifies the routing and wavelength assignment subproblems. This unified approach is found to yield significantly better solutions to the RAW problem than the earlier ones. The paper also introduces an analytical model for predicting the average number of lightpaths requests a given physical network can support.