Effect of contention resolution rules on the performance of deflection routing

Abstract

The authors investigate the effect of contention resolution (CR) rules on the performance of deflection routing. A new livelock-free prioritized CR rule, which is based on a packet's distance to the destination and the number of deflections suffered by it, is proposed. The performance--in terms of the average throughput, the average network delaym and the delay, distribution--of this CR rule is compared with those of other commonly used CR rules. Results show that prioritized CR rules improve the performance in networks using unbuffered deflection routing. It is observed that prioritized CR rules have hardly any effect on the performance of buffered deflection routing. These results suggest that using the random CR rule with output buffers is a better way to improve the performance than implementing complicated CR rules which sacrifice the switching speed inherent in deflection routing.