Improving QoS Routing Performance Under Inaccurate Link State Information

Several recent works have investigated the costs associated with QoS routing, in terms of both additional processing and increased protocol overhead, in an attempt to identify operating conditions that achieve a good trade-off between cost and performance. In this paper, we concentrate on improving this trade-off by devising methods that increase the performance of QoS routing, when cost constraints, i.e., limitations on link state updates, affect the accuracy of the information on which it operates. In particular, we study the performance of “safety-based” routing, which incorporates knowledge of the underlying inaccuracy in computing a “safety” measure for links, and uses it when computing paths. Using detailed simulations, we evaluate the effectiveness of safety-based routing and investigate the dependence of its performance on the assumptions made when computing link safety. Our findings show that for most operating conditions, safety-based routing is successful at improving routing performance while maintaining low update traffic volumes.