A New Model for Optimal Routing in All–Optical Networks with Scalable Number of Wavelength Converters1

A novel approach for modeling the optimal routing and wavelength assignment problem in wavelength division multiplexed all–optical networks is proposed. It is assumed that the optical switching nodes are equipped with a limited and scalable set of wavelength converters which can be used by any subset of incoming optical–connections. The proposed model, called the interconnected–layered–graph, provides an exact solution of the optimal routing and wavelength assignment problem in wavelength convertible networks with arbitrary number of wavelength converters at each node. Previously this problem has been modeled as optimal routing problem in electronic circuit switched networks where an incoming connection can be routed at an intermediate node on any available outgoing circuit. This assumption is not realistic in optical networks as it implies that each node is equipped with a large number of wavelength converters, such that the wavelengths of all the incoming optical connections can be converted if required. A dynamic routing and wavelength assignment scheme, which is based on the proposed interconnected–layered–graph model, is also presented and it is evaluated for various network configurations. Title subject category: Optical Systems and Networks.