Load balancing heuristics for dynamic establishment of restorable lightpaths

Efficient lightpath provisioning for dynamic traffic is an important issue in WDM optical networks. Meanwhile, in order for a lightpath to survive a network failure, both a primary lightpath and a backup lightpath need to be found for each demand. A demand is blocked if either cannot be provided. We identify 2 blocking types, and then three heuristic ideas are proposed to exploit the wavelength usage information and to use link channels more evenly across the network, leading to a lower blocking probability. Simulation shows that the load balancing routing algorithm (LBA), with our heuristic cost functions for primary path selection and backup path selection, achieves performance comparable to that of the centralized algorithm (CA). However, LBA asks for much less information to be disseminated, and therefore is more scalable.