A Trie based IP Lookup Approach for High Performance Router/Switch

Packet forwarding on the Internet takes place using the IP address of the incoming packet. Since current Internet uses CIDR based addressing scheme, finding the best match for a given destination IP is challenging. These addressing scheme uses a method called Longest Prefix Matching (LPM) to find the best match from multiple matches. There are several software based algorithm is proposed to find the LPM for given destination IP address. The number of comparisons for a given destination IP address depends on the length of the IP prefix. If the length of the IP prefix increases, the number of comparisons also increases. In the worst case, for IPv4 normally it takes 32 comparisons to find the next hop. In order to reduce the number of comparisons, this paper uses efficient compression over the IP prefixes and perform IP lookup operations over the forwarding table.