Publication

Abstract : Balancing the load between multiple paths leads to the degradation of performance in all-optical WDM networks. It is always desirable to carry the entire load on a single optimal path depending upon the current network load condition. Hence multiple lightpaths need to be maintained to provide the choice of selecting the optimal path based on the varying traffic load conditions. In this paper, we have presented a distributed dynamic multipath RWA algorithm (DDMR). In this algorithm, first, the incoming traffic is sent through all the possible paths. With the number of acknowledgements received, the source estimates the blocking probabilities of each path and the source node selects the best three paths based on lowest three blocking probabilities. Data is then classified based on their priorities. High priority data is sent through primary path, the path having the lowest blocking probability; and low priority data through secondary path, the path having the second lowest blocking probability. Backup path, which has the third lowest blocking probability, is kept for survivability of the network. With acknowledgement received on the data sent, blocking probabilities of primary path and secondary path are constantly updated. A threshold value thresh is set. Only if the maximum value of blocking probabilities of primary path or secondary path goes above the value of thresh, the algorithm restarts; by which it identifies and assigns optimal paths again. This improves the overall setup delay of the system. In addition the algorithm has a proactive approach, such that it minimizes the chance of blocking and also the approach is self-acting as it automatically changes with the traffic load variation across the network. By simulation using MATLAB, we have shown that our algorithm leads to considerably lower blocking probability, higher throughput and better channel utilization which improves the QoS of the network.