Performance of Congestion Control Mechanisms in Wormhole Routing Networks

In order to minimize latency in high-speed inter-connection networks, the wormhole routing technique can be employed. With this technique, a switch transmits an incoming message as soon as it receives it, without waiting for the entire message. The problem then is that a message stretches over several links and locks network resources, thus making a contention situation possible. Two principal congestion control mechanisms can be considered, backpressure ow control and deeection routing. The performance of these mechanisms depends both on the traac characteristics and on the network topology. In order to compare them, we study analytically the behavior of a worm-hole routing network model with random input traf-c under both policies. We estimate the probability of collision between messages and express the average message transit delay as a function of the ooered load. Simulation provides a good connrmation for the analytical results. This study gives us an understanding of the behavior of the system under diierent resource management policies.