Efficient Lightpath Routing in Wavelength-Routed Optical Networks

We propose a new lightpath routing algorithm for WDM optical networks that solves the routing and wavelength assignment (commonly known as RWA) problem dynamically and separately. The RWA problem is partitioned into two subproblems, the routing and wavelength assignment problems, and both of them are solved using the shortest path routing technique. For solving the routing subproblem, an auxiliary graph is created whereby the nodes and links in the original network are transformed to the edges and vertices, respectively, and the availability of each wavelength on the input and output links of a node as well as the number of available wavelength converters are taken into account in determining the weights of edges. Furthermore, for solving the wavelength assignment subproblem, an auxiliary graph is also utilized and the cost for wavelength conversion is taken into consideration in the edge weight function. Simulation results show that our algorithm performs much better than previously proposed algorithms in terms of blocking probability, especially if the number of wavelengths is large while the number of converters at each node is limited.