Efficient Multi-Match Packet Classification for Network Security Applications

New network applications like intrusion detection systems and packet-level accounting require multi-match packet classification, where all matching filters need to be reported. Ternary Content Addressable Memories (TCAMs) have been adopted to solve the multi-match classification problem due to their ability to perform fast parallel matching. However, TCAMs are expensive and consume large amounts of power. None of the previously published multi-match classification schemes are both memory and power efficient. In this paper, we develop a novel scheme that meets both requirements by using a new Set Splitting Algorithm (SSA). The main idea behind SSA is that it splits filters into multiple groups and performs separate TCAM lookups into these groups. It guarantees the removal of at least half the intersections when a filter set if split into two sets, thus resulting in low TCAM memory usage. SSA also accesses filters in the TCAM only once per packet, leading to low power consumption. We compare SSA with two known schemes: MUD [1] and Geometric Intersection-based solutions [2]. Simulation results based on the SNORT filter sets show that SSA uses approximately the same amount of TCAM memory as MUD, but yields a 75% to 95% reduction in power consumption. Compared with Geometric Intersection-based solutions, SSA uses 90% less TCAM memory and power at the cost of one additional TCAM lookup per packet. We also show that SSA can be combined with SRAM/TCAM hybrid approaches to further reduce energy consumption.