Hierarchical routing for large networks Performance evaluation and optimization

Abstract

Distributed adaptive routing has proven to be useful in packet switching networks. However, the storage and updating cost of this routing procedure becomes prohibitive as the number of nodes in the network gets large. This paper deals with the specification, analysis and evaluation of some hierarchical routing procedures which are effective for large store-and-forward packet-switched computer networks. The procedures studied are an extension of present techniques and rely on a hierarchical clustering of the network nodes. In particular, optimal clustering structures are determined so as to minimize the length of the routing tables required. A price for reducing the table length is the increase in the average message path length in the network. Bounds are derived to evaluate the maximum increase in path length for a given table length. From this we obtain our key result, namely, that in the limit of a very large network, enormous table reduction may be achieved with essentially no increase in network path length.