An Energy-efficient TCAM-based Packet Classification with Decision-tree Mapping

Network packet classification is a key functionality provided by modern routers enabling many new network applications such as quality of service, access control and differentiated services. Using ternary content addressable memories (TCAMs) to perform high-speed packet classification has become the de facto standard in industry. However, despite their high speed, one major drawback of TCAMs is their high power consumption. Although SmartPC, the state-of-the-art technique, was proposed to reduce power consumption by constructing a pre-classifier to activate TCAM blocks selectively, its bottom-up approach restricts its ability of grouping rules into disjoint TCAM blocks. In this paper, we propose a top-down approach for two-stage TCAM-based packet classification. The novelty of our work is the intelligent combination of software-based packet classification with TCAM-based techniques. We start by constructing a set of decision-trees for the packet classification rules, which enable the subsequent steps an excellent global view on the relationships among rules. The decision-trees are then mapped to TCAM blocks with flexible heuristics. Our top-down framework addresses the bottlenecks (the number of general rules, which have to be activated unconditionally every time) of SmartPC very effectively. Using ClassBench in our experimentations, we show that our technique is able to restrict the number of general rules to just 1% of the overall rule set. This leads to a dramatic power reduction of up to 98%, and 96% on average, which significantly outperforms SmartPC.