Exploiting Traffic Localities for Efficient Flow State Lookup

Flow state tables are an essential component for improving the performance of packet classification in network security and traffic management. Generally, a hash table is used to store the state of each flow due to its fast lookup speed. However, hash table collisions can severely reduce the effectiveness of packet classification using a flow state table. In this paper, we propose three schemes to reduce hash collisions by exploiting the locality in traffic. Our experiments show that all our proposed schemes perform better than the standard practice of hashing with overflow chains. More importantly, our move and insert to front scheme is insensitive to the hash table size.