Exploiting Traffic Localities for Efficient Flow State Lookup

Abstract

Abstract. 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.

An attack-resistant hashing scheme

“…As Internet bandwidth increases, the processing time for flow state lookup has become a critical issue. Hashing techniques are commonly used for flow state lookup [1] [2], since they can provide a constant lookup time on average, assuming that the inserted keys are uniformly distributed throughout the hash table. However, this assumption can be violated by inserting a carefully devised set of hash input keys that all map to the same hash table entry [3] [4].…”