On the modification experienced by a bursty traffic stream passing through a B-ISDN and on the congestion control problem

Abstract

In this paper we report on a study of the loss performance of a virtual circuit in a B-ISDN loaded with heterogeneous bursty sources. Such a study requires the loss characterisation of a cascade of multiplexing or switching buffered elements. The paper focuses on the analysis of the modification experienced by the arrival process of a single source when it passes through a multiplexer. We expect that the burstiness might be reduced by concatenating several nodes; this is indeed true: under suitable hypotheses, the statistical characteristics of an input stream changes stage after stage until reaching a limit behaviour. However, it is doubtful whether the limit behaviour can be used for the performance analysis of the whole network. The limit behaviour depends on the background traffic; the number of stages needed to reach the convergence to the limit behaviour depends on the characteristics of the input stream and this number is, in general, large. We show that the loss behaviour of the buffered elements within the trunk network can be very similar to that of the access one, if the number of crossed stages is low (a few units, which is likely). The main result of this work, from a modelling point of view, is that it is not strictly necessary to consider different models for the output of every buffered element in the network. The performance evaluation results are then applied to give some clues for the solution of the congestion control problem in a B-ISDN.