Adaptive routing and wavelength assignment using ant-based algorithm

We propose a new ant-based algorithm for solving the dynamic routing and wavelength assignment (RWA) problem in WDM optical networks under the wavelength continuity constraint. To facilitate the ants' foraging task, we adopt in our algorithm a routing table with the probability for route selection. The new algorithm is highly adaptive in the sense it always keeps a suitable number of ants in the network to cooperatively explore the network states and continuously update the routing tables such that the route for a connection request can be determined promptly by the current states of routing tables with a small setup delay. Some schemes for path scoring and path searching are also proposed to enhance the performance of our ant-based algorithm. Simulation results on ns-2 simulator indicate that the proposed algorithm can adapt well to the traffic variations and it is much better than the fixed routing algorithm and also outperforms the fixed-alternate routing algorithm in terms of blocking probability.