(A) traffic control algorithm for an atm switch and simulation analysis

Abstract

In this dissertation, we consider topics on the traffic control algorithm for ATM switches composed of Clos network type switch fabric. First, we develop a simulator that can be used to evaluate new traffic control algorithms for ATM switches with Clos network type switch fabric. In many cases, simulation techniques rather than analytic tools are used to evaluate the performance of the traffic control algorithms because the performance evaluation of the ATM traffic control algorithm is difficult due to consideration of source, end, and switch behavior of the ATM Forum (1996), and the complexity of the realistic traffic models. Results of some simulation tests show that the simulator can be used as a useful tool for evaluating performances and detecting some problems of the traffic control algorithm. Secondly, we present a new traffic control algorithm for ATM switches composed of Clos network type switch fabric. In most traffic control algorithms previously proposed, an ATM switch has been considered as a single node, although the switch fabric of an ATM switch is usually of a network type. This dissertation suggests a control algorithm that is designed not only for the ATM network but also for the switch fabric and that can maintain high speed even in cases where buffer capacity of the switch fabric is limited. Main modules of the suggested algorithm are a traffic status detection mechanism based on nonparametric statistical tests, a cell-loss detection mechanism, and a cluster-based fair share computation procedure. Results of simulation experiments show that the suggested algorithm satisfactorily adjusts traffic rate of available bit rate (ABR) services according to changes in traffic rate used by quality of service (QoS) guaranteed services. The results also show that the algorithm prevents cell losses relatively well and keeps the delay time of QoS guaranteed services short enough. Finally, we develop algorithms for reallocating paths of A...