Meeting delay requirements in computer networks with wormhole routing

Abstract

A well known problem with wormhole-routed packet networks is the potentially large amount of blocking that packets can experience due to link contention. Because of the very limited amount of buffering in such networks, blocked packets remain in the network and keep using network resources. Thus, blocked packets may in turn cause other packets to be blocked. This may affect a large number of packets over a large portion of the network. Proper connection management strategies and appropriate protocols must be devised to ensure that blocking of packets due to link contention is bounded. In [3], Zhao et. al. have developed a transmission control scheme that regulates the rate of transmission at each source node. A worst-case achievable utilization of 50% could be proved, using a simple regulated admission control scheme. The work of [3] assumes message streams of fixed-sized messages and fixed inter-arrival periods. In this thesis, we review the problem of routing in computer networks. Then, we examine how well does the work of [3] generalizes to message streams of variable length messages and variable inter-arrival periods. Our simulation shows that the algorithms present in [3] can be generalized even to a stochastic network. Comparisons are presented to show the difference in performance between the regulated and unregulated methods.