A processor based high-speed longest prefix match search engine

Abstract

This paper describes a new IP forwarding table search method that can be implemented on a general-purpose processor with a high-speed cache memory. It uses an efficient small data structure to store an IP forwarding table in the cache memory by exploiting a characteristic of the IP address prefixes of forwarding tables in the Internet backbone. At the particular level of the prefix-tree, the number of the prefixes below most of the nodes is very small. The method enables a general-purpose 500-MHz processor equipped with a 512-KB internal cache to perform searches at the wire-speed of a 2.4-Gb/sec link.