Preferred link based distributed adaptive routing in wavelength routed optical networks

As the WDM technology matures and the demand for bandwidth increases, dynamic provisioning of lightpaths at the WDM layer becomes an important and challenging problem. In this paper, we consider the problem of dynamic routing and wavelength assignment in wavelength-routed optical networks. The conventional approach to this problem is to select a route from a set of candidate routes, which has a common wavelength available on all the links of the route. In this paper, we propose a distributed algorithm which selects a route based on the state of the network (called preferred link approach). In this approach, a route is selected link by link based on a preference value given to each of the links. We propose three different heuristic functions for calculating the preference of the links, depending on the cost and congestion on the links. We evaluate our routing algorithm in terms of call acceptance ratio, cost of the path, hop length, and call setup time. Our experimental results suggest that our algorithm not only out performs the existing methods with respect to average call acceptance ratio. but, also improves the fairness among different hop connections, which is an important result in the case of WDM optical networks.