Impacts of link-cost and routing methods on overlay network performances for dynamic traffic grooming

Overlay IP/MPLS over WDM network is widely viewed as the most promising solution for supporting the next-generation optical Internet. The main challenge in such kind of networks typically comes from the limited information exchanges between its two layers. Though various algorithms and schemes have been proposed for traffic grooming in such overlay networks, to the best of our knowledge, there exists no systematic study for evaluating the impacts of limited information exchanges on network performance. This paper studies dynamic traffic grooming problem in overlay IP/MPLS over WDM networks. Specifically, we evaluate the impacts of the accuracy of WDM-layer link cost information and WDM-layer routing methods on the performance of overlay networks. Extensive simulation results show that i) having an appropriate link cost assignment strategy is of critical importance in deciding network performance; ii) the existence of inaccurate link cost information in overlay networks does significantly affect network performance, even when the link cost assignment strategy is carefully designed to enhance the tolerance to such inaccuracy; and iii) when subject to inaccurate link-state information, fixed and dynamic routing methods on WDM layer may not lead to significant differences in network performance.