Comparison study of delay performance between slotted and unslotted optical packet-switched star network

Abstract

This paper presents a comparison study of average queuing delay performance between slotted and unslotted all-optical packet-switched metropolitan area network (MAN) configured as star physical topology. After studying the average queuing delay performance of the two networks which are both equipped with infinite optical buffers, we research the relationship between average queuing delay and the number of optical buffers in the networks equipped with finite fiber delay lines. Considering the complexity of exact solution, we give an approximate solution. By using mathematical expressions and figures, we give the following main results: (a) for a network equipped with finite optical buffers, there exists a maximum average queuing delay; (b) when the numbers of fiber delay lines that are respectively equipped to slotted and unslotted network is same, the maximum average queuing delay of unslotted network is bigger than that of slotted network; (c) there exist the best N1 and N2 (the number of optical fiber delay lines), which can bring on the best average queuing delay performance of slotted network that is equipped with finite optical buffers.