K. G. Ramakrishnan

On-line routing for permanent virtual circuits

The paper considers the problem of routing a set of permanent virtual circuit requests over a backbone network. Several factors make this routing problem complicated. Routing decisions must be made on-line without any knowledge of future request sets. Furthermore, frequent rerouting to correct inefficiencies that can result from the on-line routing decisions is not possible since rerouting creates a service disruption for the customer. Finally, the forward and reverse bandwidth of a virtual circuit must be routed over the same single path. Using an extensive set of simulations, the paper evaluates several different strategies for on-line permanent virtual circuit routing. The authors find that a strategy based on results in competitive analysis and ideas from combinatorial optimization consistently provides the best performance. The problem of admission control is closely related to the problem of routing. The paper also provides a theoretical lower bound that suggests that non-greedy admission control is a fundamental component of an efficient on-line permanent virtual circuit routing algorithm.