Theory of periodic contention and its application to packet switching

The following model of a packet switch is considered: at each clock tick, the switch attempts to route the head-of-line packet at the buffer of every input port to its destination port. Each output port can receive only one packet at a time, but there may be packets from multiple inputs destined for common output. The switch first selects exactly one packet for each requested output and then routes all selected packets through a self-route interconnection network such as the Batcher-Banyan network. Based on the traffic assumption of periodic packet streams, the necessary and sufficient clock rate is determined in order for the switch to be nonblocking. This result has turned out to be quite different from analyses based on the assumption of random traffic