Separator-Based Strategies for Efficient Message Routing (Preliminary Version)

o. Abstract. Message routing strategies are given for networks with certain separator proper­ ties. These strategies use" considerably less space than complete routing tables, keep node names to O{log n) bits, and still route along near-shortest paths. For any network with separators of size at most a small constant c, a total of 0 (n log n) items of routing information is stored, and any message is routed along a path of length at most (2/0.) + 1 times the length of an optimal path, where 0, > 1 is the positive root of the equa­ tion o.r(c+1)/21 - 0, - 2 = o. For planar networks, O(n 1+£) items are stored, for any constant E, 0 < E < 1/3, and the length of any message path is at most 7 times that of an optimal path.