Performance analysis of input and output queueing packet switch with multiple priority classes

This paper proposes an N × N input-output buffered switch model which switches several kinds of packets emphasizing the real-time property as well as packets emphasizing the secure transmission. The model corresponds to the Poisson and Bernoulli traffic switching system. Such performances as the average system queueing delay and the loss probability for the packet emphasizing the real-time transmission are analyzed. Nonpreemptive priority discipline is applied on the input side where the circuit configuration is relatively simple. On the output side, the first-come/first-served (FCFS) process is applied without considering the priority service. In the proposed model, the output buffer size is assumed as finite and the input buffer size is assumed as infinite. For the two kinds of switching systems which serve the Poisson arrival packets and the Bernoulli arrival packets, respectively, the mean system queueing delay for the priority class is analyzed. For the case where the input buffer size is limited for the packet with a high priority emphasizing the real-time transmission, the relation between the loss probability for the packet with a high priority and the sizes of the input and output buffers is investigated by a computer simulation for the case of two classes. The adequate input buffer size for the packet with a high priority is determined.