A high-throughput and high-capacity IPv6 routing lookup system
With the growing number of routing entries, IP routing lookup has become the major performance bottleneck in backbone routers. In this paper, a complete hardware-based routing lookup system is proposed to achieve high-throughput and high-capacity for IPv6. The proposed system is a cache-centric, hash-based architecture that contains a routing lookup application specific integrated circuit (ASIC) and a memory set. A hash function is used to reduce lookup time for the routing table and ternary content addressable memory (TCAM) effectively resolves the collision problem. The gate count of the ASIC, excluding the binary content addressable memory (BCAM), is about 5306 gates, using an in-house 0.18@mm CMOS single-poly six-metal standard cell library. The results of post-layout simulations show that the ASIC operates in 3.6ns so that the routing lookup system approaches 260 Mega lookups per second (Mlps), which is sufficient for 100Gbps networks. The memory density is good, with each routing entry requiring only 64bits. Moreover, the routing table only needs 10.24KB on-chip BCAM, 20.04KB off-chip TCAM and 29.29MB DRAM for 3.6M routing entries in the proposed system.