A Fast Head-Tail Expression Generator for TCAM -- Application to Packet Classification

Abstract

This paper presents a method to generate head-tail expressions for Ternary Content Addressable Memories (TCAMs). First, we derive head-tail expressions for interval functions. We introduce a fast prefix sum-of-product (PreSOP) generator (FP) which generates products using the bit patterns of the endpoints. Next, we propose a direct head-tail expression generator (DHT). Experimental results show that DHT generates much smaller TCAM than FP. The proposed algorithm is useful for simplified TCAM generator for packet classification.