Performance analysis of an input and output queueing packet switch with a priority packet discarding scheme

In future high-speed integrated networks, packet switches must accommodate diverse types of applications with different qualities of service (QOS) and traffic requirements. Therefore some types of priority-control schemes are needed in packet switches, in order to increase the utilisation of switches and to satisfy the QOS of each traffic type. The authors consider a nonblocking input and output queueing packet switch with capacity m, in which two classes of traffic are admitted. Each input queue adopts the priority packet discarding scheme, which discards arrivals of low-priority traffic when its queue length is greater than the pre-defined threshold value. The authors obtain the distribution of input-queue length and loss probabilities of each class using a matrix-geometric solution method. By numerical analysis and simulation, it is shown that the utilisation of the switch with the priority packet discarding scheme satisfying the QOS of each traffic class is much higher than that of the switch without control, and the required buffer size is reduced while satisfying the same QOS.