Analytical Models of Adaptive Routing StrategiesW

Adaptive routing algorithms have been frequently suggested as a means of improving communication performance in multicomputers. These algorithms, unlike deterministic routing, can utilize network state information to exploit the presence of multiple paths. Adaptive routing, however, is complex and expensive. Before such schemes can be successfully incorporated in multiprocessor systems, it is necessary to have a clear understanding of the factors which aaect their performance potential. In this paper we present a simple and eecient scheme to model the performance of idealized adaptive routing. We evaluate a basic, high-performance adaptive system using an analytic queueing model which approximates its behavior. This analytic model predicts the performance of networks with varying parameters, and provides insight into the nature of message traac. We have also conducted extensive simulation experiments, the results of which are used to validate the analytic model and to identify some of the conditions which promote high performance of adaptive routing in a communication network.