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Virtual Topology Reconfiguration with Protection Method in WDM Networks

In this paper, we present a new approach for the problem of logical topology reconfiguration in WDM networks. The reconfiguration algorithms attempt to keep the network availability as much as possible during the reconfiguration process. Most studies on methods to design a logical topology provide optimization formulations and their solutions under the assumption that the traffic requirements are known in advance. In practice, traffic demands change due to new services. When it does, a new optimal topology should be obtained. In the proposed algorithm, we assign subsidiary lightpath for each current lightpath. The resources of subsidiary lightpaths are not used for traffic transportation. If the lightpath exchanging is necessary during the reconfiguration process, we use subsidiary lightpaths to handle traffic without any rerouting. The proposed algorithm was evaluated by using OWns simulator. The NSFNET network topology with 14 nodes and 21 links was used for performance evaluation. The results show that the number of lost packets and blocking probability are remarkably reduced