A hybrid algorithm for dynamic lightpath protection in survivable WDM optical networks

Dynamic lightpath protection in survivable WDM networks requires finding a pair of diverse routes (i.e., a primary route and a backup route that are link-disjoint) that form a cycle upon the arrival of a new connection request. In this paper, we propose a novel hybrid algorithm for this problem based on a combination of the mobile agents technique and genetic algorithms (GA). By keeping a suitable number of mobile agents in the network to cooperatively explore the network states and continuously report diverse routes into the routing tables, our new hybrid algorithm can promptly determine the first population of cycles for a new request based on the routing table of its source node, without requiring the time consuming process associated with current GA-based lightpath protection schemes. We furthermore improve the performance of our algorithm by introducing a more advanced fitness function. Extensive simulation studies on the ns-2 network simulator show that our hybrid algorithm achieves a significantly lower blocking probability and a smaller execution time than the conventional survivable routing algorithms.