Advanced Hash Algorithms with Key Bits Duplication for IP Address Lookup

Hashing technique have been widely adopted for various computer network applications such as IP address lookup and intrusion detection, among which XOR-hashing is one of most popular techniques due to its relatively small hash process delay. In all the current commonly used XOR-hashing algorithms, each of the hash key bits is usually explicitly XORed only at most once in the hash process, which may limit the amount of potential randomness that can be introduced by the hash process. This paper looks into the possibility in duplicating/reusing key bits to inject additional randomness into the hash process thus enhancing the overall performance further. However, when a key bit is reused, newly induced correlation arises among resulted hash bits where key bits are shared which may easily offset the intended benefit from bit duplication. The novel hash technique introduced in this paper shows how to intelligently apply bit duplication while minimizing the amount of correlation induced in the duplication process.