Two deterministic routing networks are presented: the pruned butterfly and the sorting fat-tree . Both networks are area-universal, that is, they can simulate any other routing network fitting in similar area with polylogarithmic slowdown. Previous area-universal networks were either for the off-line problem, where the message set to be routed is known in advance and substantial precomputation is permitted, or involved randomization, yielding results that hold only with high probability. The two networks introduced here are the first that are simultaneously deterministic and on-line, and they use two substantially different routing techniques. The performance of their routing algorithms depends on the difficulty of the problem instance, which is measured by a quantity λ known as the load factor. The pruned butterfly runs in time O (λlog 2 N ), is the number of possible sources and destinations for messages and λ is assumed to be polynomial in N . The sorting fat-tree algorithm runs in O (λ log N + log 2 N ) time for a restricted class of message sets including partial permutations. Other results of this work include a “flexible” circuit that is area-time optimal across a range of different input sizes and an area-time lower bound for routers based on wire-length arguments.

Two deterministic routing networks, the pruned butterfly and the sorting fat-tree, are presented. Both networks are area universal, i.e. they can simulate with polylogarithmic slowdown, any other routing network fitting in similar area. Previous area-universal networks were either for the offline problem, where the message set to be routed is known in advance and substantial precomputation is permitted, or involved randomization, yielding results that hold only with high probability. The present networks are the first that are simultaneously deterministic and online, and they use two substantially different routing techniques. The performance of the routing algorithms depends on the difficulty of the problem instance, which is measured by a quantity lambda , known as the load factor. The pruned butterfly algorithm runs in time O( lambda log/sup 2/N), where N is the number of possible sources and destinations for messages and lambda is assumed to be polynomial in N. The sorting fat-free algorithm runs in O( lambda log N + log/sup 2/N) time for a restricted class of message sets, including partial permutations. Other results include a new type of sorting circuit, an area universal circuit, and an area-time lower bound for routers.>