Mathematical analysis of the input-queued packet switch under multicast traffic

This paper deals with input-queued packet switches loaded with multicast traffic. An (N×N) packet switch is considered, operating in a synchronous slotted fashion, on fixed-size data units (called interchangeably as cells or fixed-length packets). A switch scheduler identifies a set of non-conflicting inputs during each time slot. Since service of multiple cells from the same input requires internal speed-up or switch fabric expansion, it is assumed that the switch follows the restricted rule i.e., only one cell can be switched from one input port and only one cell can be switched to one output port during one time slot. The performance of such a switch is analysed and the equations for the performance metrics such as saturation throughput, mean cell delay and average queue length are derived. It is assumed that there are 2^N-1 queues at each input port to achieve optimal switch performance. While this may not be possible for large switch sizes, it is believed that it is necessary to use switches of smaller sizes with 2^N-1 queues at each input, to completely eliminate head-of-line blocking and achieve optimal performance.