A Flexible Routing Scheme for Networks of Workstations

Abstract

NOWs are arranged as a switch-based network which allows the layout of both regular and irregular topologies. However, the irregular pattern interconnect makes routing and deadlock avoidance quite complicated. Current proposals use the up*/down* routing algorithm to remove cyclic dependencies between channels and avoid deadlock. Recently, a simple and effective methodology to compute up*/down* routing tables has been proposed by us. The resulting routing algorithm is very effective in irregular topologies. However, its behavior is very poor in regular networks with orthogonal dimensions. Therefore we propose a more flexible routing scheme that is effective in both regular and irregular topologies. Unlike up*/down* routing algorithms, the proposed routing algorithm breaks cycles at different nodes for each direction in the cycle, thus providing better traffic balancing than that provided by up*/down* routing algorithms. Evaluation results modeling a Myrinet network show that the new routing algorithm increases throughput with respect to the original up*/down* routing algorithm by a factor of up to 3:5 for regular networks, also maintaining the performance of the improved up*/down* routing scheme proposed in [7] when applied to irregular networks.

This work was supported by the Spanish CICYT under Grant TIC97-0897-C04-01.