Large-scale wire-speed packet classification on FPGAs

Abstract

Multi-field packet classification is a key enabling function of a variety of network applications, such as firewall processing, Quality of Service differentiation, traffic billing, and other value added services. Although a plethora of research has been done in this area, wire-speed packet classification while supporting large rule sets remains difficult. This paper exploits the features provided by current FPGAs and proposes a decision-tree-based, two-dimensional dual-pipeline architecture for multi-field packet classification. To fit the current largest rule set in the on-chip memory of the FPGA device, we propose several optimization techniques for the state-of-the-art decision-tree-based algorithm, so that the memory requirement is almost linear with the number of rules. Specialized logic is developed to support varying number of branches at each decision tree node. A tree-to-pipeline mapping scheme is carefully designed to maximize the memory utilization. Since our architecture is linear and memory-based, on-the-fly update without disturbing the ongoing operations is feasible. The implementation results show that our architecture can store 10K real-life rules in on-chip memory of a single Xilinx Virtex-5 FPGA, and sustain 80 Gbps (i.e. 2x OC-768 rate) throughput for minimum size (40 bytes) packets. To the best of our knowledge, this work is the first FPGA-based packet classification engine that achieves wire-speed throughput while supporting 10K unique rules.