More on the Efficiency of Interval Routing

Interval routing is a space-efficient routing method for computer networks. The method is said to be optimal if it can generate optimal routing paths for any source-destination node pair. A path is optimal if it is a shortest path between the two nodes involved. A seminal result (The Computer Journal, 34 (1991), 475–476) in the area, however, has pointed out that “the interval routing algorithm cannot be optimal in networks with arbitrary topology.” The statement is correct but the lower bound on the longest routing path that was derived is not. We give the counterproof in this paper and the corrected bound.