Hot-potato worm routing is almost as easy as store-and-forward packet routing

The theory of worm routing (rather than packet routing) recently attracts an increased attention as an abstraction of the underlying communication mechanisms in many parallel machines. Routing the worms in the hot-potato style is a desired form of communication in high-speed optical interconnection networks. The authors develop a simple method for the design of parallel hot-potato worm routing algorithms. The basic approach is to simulate known packet routing algorithms, so that in each step worms are moved around instead of packets. For hot-potato permutation routing of worms of size k the authors have the following results. They get a O(k^2.5n ) algorithm for the n×n mesh, and a O (k^1.5n) algorithm for the corresponding offline problem. For the 2ⁿ-nodes hypercube they get a O(k³n log ² n) deterministic algorithm, and a O(k³ n) randomized algorithm. Although the results are given for permutation routing on the mesh and the hypercube, the general method can be applied to many other networks and to more general communication patterns as well. Moreover, once better routing algorithms are found for the underlying network, the worm routing algorithm improves, too