Solving the static design routing and wavelength assignment problem

Abstract. In this paper we present a hybrid model for the static design variant of the routing and wavelength assignment problem in directed networks, an important benchmark problem in optical network design. Our solution uses a decomposition into a MIP model for the routing aspect, combined with a graph coloring step modelled using either MIP (Coin-OR), SAT (minisat) or finite domain constraints (ECLiPSe). We consider two possible objective functions, one minimizing the maximal number of frequencies used on any of the links, the other minimizing the total number of frequencies used. We compare the models on a set of benchmark tests, results show that the constraint model is much more scalable than the alternatives considered, and is the only one producing proven optimal or near optimal results when minimizing the total number of wavelengths.