An Observation of Packet Classification: Most Rules are at the Top

Multi-field packet classification plays a critical role in a modern computer network. Many algorithms are designed, but the analysis of the rule sets is insufficient. In this paper, we analyze the rule sets from the aspect of rule overlapping with the tools from graph theory and network verification. The correctness of some designs is confirmed, such as the partition is necessary. We also propose a patch, PCG, based on our observation that most rules are at the top. PCG can apply to various algorithms to further improve the classification performance. We evaluate PCG on a state-of-art algorithm, CutSplit, and find that PCG introduces about 20% throughput improvement.