Improved Architectures for Range Encoding in Packet Classification System

Abstract

Packet classification is an important aspect of modern network systems. Packet classification systems have traditionally been built utilizing Ternary Content Addressable Memory (TCAM) due to the high throughput needed. However, TCAMs are expensive in terms of area and power consumption. An alternative to TCAM based systems using SRAM and a novel rule encoding method has been proposed to match multiple packets simultaneously (using multiple store_compare_units). This alternative achieves similar or better throughput than the traditional TCAM approach while occupying smaller space and consuming less energy. This paper revamps the existing SRAM-based architecture to reduce area and power consumption without threatening throughput. Two methods are shown. The first method allows for range encoding SRAMs to be shared between store_compare_units (SCUs) to lower area and power consumption with minor effect on throughput. The second method discusses a hybrid system allowing rules with prefixes (single rules) and ranges (rules which match a range of addresses, usually translated to many prefixes) to exist in parallel for the same domain. This allows for lower power consumption than utilizing fixed range encoding due to optimization of the ruleset. Results show that this hybrid architecture saves more than 20% of power/field if half of the TCP ports contain ranges (and the other half contains prefixes). The new extensions have been tested in over ten benchmarks (including the SNORT ruleset) to verify the claimed improvements.