Flow-level performance analysis of a multi-rate system supporting stream and elastic services

We consider a multi-rate system where stream and elastic flows receive service. Both the stream and the elastic classes are associated with peak rate limitation. In contrast to the constant bit rate stream flows, the elastic flows tolerate bandwidth compression while in service. Because of the occasional bandwidth compression, the holding time of elastic flows depends on their perceived throughput. Although this model is Markovian under quite non-restrictive assumptions, the model's state space grows exponentially with the number of traffic classes. The model is not quasi-reversible, and therefore, it cannot be evaluated by efficient recursive formulae. We propose a method whereby the original state space is mapped to a two-dimensional one, independently of the number of the stream and the elastic traffic classes. The special structure of the two-dimensional model allows us to develop an efficient method that approximates the average throughputs of elastic flows. The state space reduction together with the proposed approximation provides a powerful tool for the performance analysis of this model as it allows the approximation of the average throughputs of elastic flows reasonably accurately in large models as well. Copyright (c) 2012 John Wiley & Sons, Ltd.