An Evaluation of Routing Algorithms for Distributed Light path Establishments in WDM Network

摘要

Many researches on the routing and wavelength assignment algorithms have assumed that the global link state information is obtained without any delays. For a distributed lightpath establishment environment, how-ever, the blocking probability requests much depends on both the accuracy of the global link state information and distributed protocols for wavelength reservation. One promising approach for the distributed wavelength reservation is to use backward reservation protocol, where the usage of the wavelength resources is collected along the forward path and wavelength resources are reserved along the backward path. Therefore, frequent link state exchange and details on link state information, such as usage of each wavelength, may not be necessary since those information is collected on-demand basis. This paper first discusses the role of the routing algorithm in WDM networks and then investigate how the frequency of link state information exchange affect the blocking probability of lightpath establishments. The simulation results show that less details on link state and less frequent link state exchange is enough for the routing algorithm when the backward reservation protocol is used, whereas conventional reservation protocol greatly affected by the frequency of link state information exchange.