Universal wormhole routing

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(cdη+dη log P) time with high probability, where L is the number of flits in a packet, and η=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 ⊖(A) can simulate wormhole routing on any network of comparable area with O(log³ 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