Dimensioning an ATM switch based on a three-stage Clos interconnection network

ATM (asynchronous transfer mode) is a new technique for transmitting voice, data and video. The performance of atm networks will depend on switch structure. Performance analysis of an atm switch based on a three-stage Clos network is presented. In this paper two types of switches are studied: a switch with input queues in the switching elements and a switch with output queues. This study is at the cell level and intends to dimension the switch. First, the traffic is supposed to be uniform, cells arrive on each input according to a geometric arrival process, they are uniformly directed over all the network outputs. An analytic model is proposed for both input and output queues in the switching elements. A study of the saturation throughput is proposed for input buffer switching elements. This work proves the influence of buffer dimensioning on the different stages of the switch. Dissymmetric switching elements are shown to be better than symmetric ones. A model is then designed for nonuniform traffic patterns and output buffers. Two types of non-uniform traffic are presented: single source to single destination (sssd) and multi-hot spots traffic (mhs). Discrete event simulations are used to validate the different models.