Evaluation of A Load Pro ling Approach to Routing Guaranteed Bandwidth Flows

To support the diverse Quality of Service (QoS) requirements of real-time (e.g. audio/video) applications in integrated services networks, several routing algorithms that allow for the reservation of the needed bandwidth over a Virtual Circuit (VC) established on one of several candidate routes have been proposed. Traditionally, such routing is done using the least-loaded concept, and thus results in balancing the load across the set of candidate routes. In a recent study, we have established the inadequacy of this load balancing practice and proposed the use of load pro ling as an alternative. Load pro ling techniques allow the distribution of \available" bandwidth across a set of candidate routes to match the characteristics of incoming VC QoS requests. In this paper we thoroughly characterize the performance of VC routing using load pro ling and contrast it to routing using load balancing and load packing. We do so both analytically and via extensive simulations of multi-class tra c routing in Virtual Path (VP) based networks. Our ndings con rm that for routing guaranteed bandwidth ows in VP networks, load balancing is not desirable as it results in VP bandwidth fragmentation, which adversely a ects the likelihood of accepting new VC requests. This fragmentation is more pronounced when the granularity of VC requests is large. Typically, this occurs when a common VC is established to carry the aggregate tra c ow of many high-bandwidth real-time sources. For VP-based networks, our simulation results show that our load-pro ling VC routing scheme performs better or as well as the traditional load-balancing VC routing in terms of revenue under both skewed and uniform workloads. Furthermore, load-pro ling routing improves routing fairness by proactively increasing the chances of admitting high-bandwidth connections.