Don't-Care Gating (DCG) TCAM Design Used in Network Routing Table

This paper presents a low-power ternary content addressable memory (TCAM) design, in which we propose the don't-care gating (DCG) scheme that aims to reduce the TCAM power dissipated in the search-line (SL) switching activity. By exploiting the vertically continuous “don't-care” feature, the DCG scheme can effectively reduce the average SL power consumption per switch. In addition, we also develop the refined search enable (RSE) technique to eliminate the unnecessary SL switching activity in the quiet pattern. By reducing both the SL switching activity and the average switching power, the proposed design can minimize the TCAM SL power consumption. For a 128 × 32 TCAM, the best configuration we examined shows that when the gating granularity is 16, with a 1.3% search performance improvement, the DCG scheme combined with the RSE technique can achieve 72%~79% SL energy reduction.