Guaranteeing Seamless End-to-End QoS in OBS Networks

In this paper the authors propose a method to guarantee end-to-end QoS to multiple traffic classes in optical burst switched (OBS) scenario, even in case of network congestion. The OBS network utilizes a core node architecture with no fiber delay lines and a limited set of wavelength converters. Traffic class performance differentiation is achieved by allowing high class traffic to utilize more node functionalities than low class traffic. To improve the likelihood of finding a route, even upon network congestion, bursts are allowed either to be deflected from their default route or to choose from a set of preplanned end-to-end paths. Network performance evaluation is focused on burst blocking probability and end-to-end TCP throughput. Performance is determined under the assumption of exponentially distributed burst interarrival times and arbitrarily distributed burst durations. Numerical results show that the proposed approach is able to guarantee different end-to-end TCP throughput performance to each traffic class. Moreover the proposed burst routing policies allows to decrease, with respect to a shortest path routing policy, the burst blocking probability. Thus the end-to-end TCP throughput is seamlessly guaranteed even in case of network congestion.