Universal wormhole routing
Ronald I. Greenberg, Hyeong-Cheol Oh · IEEE Transactions on Parallel and Distributed Systems · 1997
We examine the wormhole routing problem in terms of the "congestion" c and "dilation" d for a set of packet paths. We show, with mild restrictions, that there is a simple randomized algorithm for routing any set of P packets in O(cd/spl eta/+d/spl eta/ log P) time with high probability, where L is the number of flits in a packet, and /spl eta/=min {d, L}; only a constant number of flits are stored in each queue at any time. Using this result, we show that a fat tree network of area /spl ominus/(A) can simulate wormhole routing on any network of comparable area with O(log/sup 3/ A) slowdown, when all worms have the same length. Variable length worms are also considered. We run some simulations on the fat tree which show that not only does wormhole routing tend to perform better than the more heavily studied store and forward routing in this context, but that performance superior to our provable bound is attainable in practice.