Overflow Buffer in Crossbar -A New Architecture for High Performance Routers

R. He and J.G. Delgado-Frias (USA)


Overflow buffer, buffer architecture, crossbar, iSLIP.


As the Internet grows, high performance routers and switches are required to have higher bandwidth and lower delay latency at the same time. At present, most of these routers and switches are implemented on crossbar as the switched backplane. Normally, the crossbar is based on symmetric buffer architecture. In this paper, we first introduce a new asymmetric buffer architecture for the crossbar in which a new port and a local shared bus are added. We then evaluate the performance of this new asymmetric buffer architecture and simulate under different bus arbitration and buffer management algorithms. Our studies indicate that we could get much improvement for the throughput and low drop rate using this new asymmetric architecture, though the latency is increased at the same time. Considering that the Internet is based on best-effort packet switching, we think that high throughout and low drop rate is much more preferred in case of the retransmission of the TCP/IP's ARQ (Automatic repeat request) scheme. Thus we could save a lot of expensive link bandwidth and decrease the probability of congestion for the network.

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