Efficient TCAM Design Based on Multipumping-Enabled Multiported SRAM on FPGA

Abstract

Ternary content-addressable memory (TCAM)-based search engines play an important role in networking routers. The search space demands of TCAM applications are constantly rising. However, existing realizations of TCAM on field-programmable gate arrays (FPGAs) suffer from storage inefficiency. This paper presents a multipumping-enabled multiported SRAM-based TCAM design on FPGA, to achieve an efficient utilization of SRAM memory. Existing SRAM-based solutions for TCAM reduce the impact of the increase in the traditional TCAM pattern width from an exponential growth in memory usage to a linear one using cascaded block RAMs (BRAMs) on FPGA. However, BRAMs on state-of-the-art FPGAs have a minimum depth limitation, which limits the storage efficiency for TCAM bits. Our proposed solution avoids this limitation by mapping the traditional TCAM table divisions to shallow sub-blocks of the configured BRAMs, thus achieving a memory-efficient TCAM memory design. The proposed solution operates the configured simple dual-port BRAMs of the design as multiported SRAM using the multipumping technique, by clocking them with a higher internal clock frequency to access the sub-blocks of the BRAM in one system cycle. We implemented our proposed design on a Virtex-6 xc6vlx760 FPGA device. Compared with existing FPGA-based TCAM designs, our proposed method achieves up to 2.85 times better performance per memory.