Alternate Routing Algorithms for Distributed Lightpath Establishment in WDM networks

摘要

Previous studies on routing and wavelength assignment algorithms assumed that the global link state information is obtained without delays and route is selected adaptively. However, in distributed lightpath establishment, if sender nodes select the route adaptively, the blocking probability increases because of the delayed link state information, On the other hand, with alternate routing algorithm, the sender node selects next route in pre-defined routes if path setup fails. Therefore the performance degradation is small in alternate routing. In this paper, we evaluate the average path setup time for routing algorithms in distributed networks to clarify the effect of delayed link state information. The simulation results show that an adaptive routing algorithm (least loaded algorithm) is much affected by the delayed link state information. The results also show that a new routing algorithm (FAR with ISP and LL) performs better than other routing algorithms, especially in the distributed environment.