Interoperability among explicit rate congestion control algorithms for ABR service in ATM networks

This paper investigates the important issue of interoperability among different explicit-rate congestion control algorithms in multi-vendor (heterogeneous) ATM networks. We assume that each switch in the network implements only one of several known explicit-rate congestion control algorithms. We investigate potential unfairness problems resulting from situations whereby certain ABR sources receive network feedback from different switches and other sources responding to feedback coming from a subset of switches. The paper identifies three types of unfairness problems that arise in such networks. One type of unfairness appears while the sources are increasing their rates and the second type appears while they are decreasing their rates. The third type is a new cause of unfairness generated by the presence of highly bursty VBR traffic which can cause unfairness not only in the steady-state periods but even in the transient-state periods on a network link. In addition to identifying the causes of unfairness, our results provide quantitative evaluation of the level of unfairness as a function of various network and source parameters.