Design and Buffer Sizing of TCAM-Based Pipelined Forwarding Engines

The ever increasing line speed and the continuous growing demands of various functions support(for example QoS, multicast and security) have interact- tively made it harder for forwarding engines to process packets at line speed, and this will increasingly make the forwarding engines call for additional buffers to accommodate the burst transmission and decrease the packet loss rate. In this paper, a high-speed pipeline designed for TCAM-based forwarding engines is presented, and its buffer analysis model is also given, then, the buffer requirement of the forwarding engine is analyzed under two conditions: the forwarding rate is not less than and less than the input rate. Our analysis results and experiments both show that, the proposed forwarding pipeline is of high performance, and just one pipeline can easily deal with the data transfer rate of 30 Gb/s or even higher; the pipelined forwarding engine only need to buffer a several packets, then the loss rate will be an acceptable value or even zero, further increasing the buffer size will have little effect on reducing the loss rate.