A Novel Rule Mapping on TCAM for Power Efficient Packet Classification

Abstract

Packet Classification is the enabling function performed in commodity switches for providing various services such as access control, intrusion detection, load balancing, and so on. Ternary Content Addressable Memories (TCAMs) are the de facto standard for performing packet classification at high speeds. However, TCAMs are highly costlier both in terms of cost and power consumption, forcing the switch vendors towards placing lots of effort for power management. Hence, power-efficient solutions for TCAM-based packet classification are highly relevant even today. In this article, we propose a novel rule placement algorithm based on the unique field values’ presence within the rule databases. We evaluate the total search that is needed to be inspected with respect to the traditional placement approach and the proposed placement approach based on the information content within the fields. Simulation results showed an average reduction of 30.55% in the search space by the proposed placement approach, thereby resulting in an average reduction of 18.85% per search energy over TCAM. With typical TCAM clock speeds ranging between 200--400MHz, this reduction in the per-search energy maps to a huge reduction in the total energy consumed by the TCAM-based network switches. The proposed solution is plug-and-play type requiring only minimal pre-processing within the Network Processing Unit (NPU) of the switches and edge routers.