Alternate Routing Algorithms for Distributed Lightpath Establishment in WDM networks

Abstract Previous studies on routing and wavelength assignment algorithms assumed that the global link state information is obtained without delays. However, in distributed lightpath establishment, sender nodes need an adaptive routing algorithm to achieve less probability of request blocking. On the other hand, with alternate routing algorithm, the sender node selects next route if path establishment fails. In consequence, the performance degradation because of worse route selection is expected smaller than adaptive routing algorithm. And an adaptive alternate routing algorithm where the delayed link state information is considered to perform better. In this paper, we evaluate the average path setup time for routing algorithms to clarify the effect of delayed link state information. The simulation results show that an adaptive routing algorithm (least loaded algorithm) is affected by the delayed link state information. And a new routing algorithm (FAR with 1SP and LL) performs better than other routing algorithms, and the effect of delayed link state information is small