A Parallel Multiple Hashing Architecture Using Prefix Grouping for IP Address Lookup

The primary function of the Internet routers is to forward incoming packets toward their final destinations. IP address lookup is one of the most important functions in evaluating router performance since IP address lookup should be performed in wire-speed for the hundred-millions of incoming packets per second. With CIDR, the IP prefixes of routing table have arbitrary lengths, and hence address lookup by exact match is no longer valid. As a result, when packets arrive, routers compare the destination IP addresses of input packets with all prefixes in its routing table and determine the most specific entry among matching entries, and this is called the longest prefix matching. In this paper, based on parallel multiple hashing and prefix grouping, we have proposed a hardware architecture which performs an address lookup with a single memory access.