Pipelined Parallel AC-Based Approach for Multi-String Matching

New applications such as real-time packet processing require high-speed string matcher, and the number of strings in pattern store is increasing to tens of thousands, which requires a memory efficient solution. In this paper, a pipelined parallel approach for hardware implementation of Aho-Corasick (AC) algorithm for multiple strings matching called P2-AC is presented. P2-AC organizes the transition rules in multiple stages and processes in pipeline manner, which significantly simplifies the DFA state transition graph into a character tree that only contains forwarding edges. In each stage, parallel SRAMs are used to store and access transition rules of DFA in memory. Transition rules can be efficiently stored and accessed in one cycle. The memory cost is less than 47% of the best known AC-based methods. P2-AC supports incremental update and scales well with the increasing number of strings. By employing two-port SRAMs, the throughput of P2-AC is doubled with little control overhead.