A TCAM - Based Distributed Parallel IP Lookup Scheme and Performance Analysisi

Using Ternary Content Addressable Memory (TCAM) for high speed IP address lookup has been gaining popularity due to TCAM's deterministic performance and fast lookup performance. However, restricted by the slow improvement of memory accessing speed, the route lookup engines for next-generation terabit routers demand exploiting parallelism among multiple TCAM chips. Traditional parallel methods always incur excessive redundancy and high power consumption. We propose in this paper an original TCAM-based IP lookup scheme that achieves an ultra high lookup throughput and a high utilization of the memory while being power efficient. In our multi-chip scheme, we devise a load-balanced TCAM table construction algorithm together with an adaptive load balancing mechanism. The power efficiency is well controlled by decreasing the number of TCAM entries triggered in each lookup operation. Using four 133MHz TCAM chips and given 25% more TCAM entries than the original route table, the proposed scheme achieves a lookup throughput of up to 533Mpps. Furthermore it is worst-case performance guaranteed (no less than 464Mpps, according to our theoretical analysis) and simple for ASIC implementation. Keywords—TCAM, IP, route lookup, throughput, power consumption