Congestion-Free Routing on the CM-5 Data Router

Even though the CM-5 data router employs randomization, some permutations can be routed more quickly than random permutations with the same bisection requirements. In this paper we describe a class of permutations called congestion-free permutations and show how they can be used to accomplish important communication problems including all-to-all personalized communication, hypercube dimension-exchange, block transfer, and others.