Dynamic Reconfigurable Ternary Content Addressable Memory for OpenFlow-Compliant Low-Power Packet Processing

摘要

OpenFlow, the main protocol for software-defined networking (SDN) advocated by Google, requires multiple flow tables with long and variable rule lengths. For fast packet forwarding, using ternary content-addressable memory (TCAM) as implementation of lookup-table has displayed superior performance in executing the conventional packet classification algorithms. However, applying traditional TCAM designs to an OpenFlow switch leads to problems of insufficient word length, inflexible table configuration, and high-power consumptions. This paper presents a low-power dynamic reconfigurable TCAM design for OpenFlow-compliant packet processing. It can support long and variable word lengths for different flow tables, with less than 5% of area overhead. To reduce dynamic power consumption without sacrificing throughput, the proposed hybrid-pipelined structure based on NAND-NOR CAM and pipelined-TCAM, can achieve lower energy-delay products than traditional TCAM. Moreover, the proposed self-power gating technique controlled by the mask data optimizes both NAND and NOR core cells, which lowers power consumption without additional control and routing overhead. Finally, the low-power reconfigurable TCAM is implemented in TSMC 40 nm CMOS technology. The implementation results show that the energy metric of the proposed reconfigurable TCAM is only 0.177 fJ/bit/search, at a 416 MHz operating frequency. Thus, the proposed TCAM design is very suitable for the emerging high performance packet processing in future SDN applications that need long and variable word lengths.