A TCAM generator for packet classification

Abstract

In the internet, packets are classified by source and destination addresses and ports, as well as protocol type. Ternary content addressable memories (TCAMs) are often used to perform this operation. This paper shows a method to reduce the number of words in TCAM for multi-field classification functions. We use head-tail expressions to represent a multi-field classification rule. Furthermore, we present an O(r2)-algorithm, called MFHT, to generate simplified TCAMs for two-field classification functions, where r is the number of rules. Experimental results show that MFHT achieves a 58% reduction of words for random rules and a 52% reduction of words for ACL and FW rules. Moreover, MFHT is fast and useful for simplifying TCAM for packet classification.