Routing Lookups in Hardware at Memory Access Speeds

14 years 3 months ago

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Increased bandwidth in the Internet puts great demands on network routers; for example, to route minimum sized Gigabit Ethernet packets, an IP router must process about packets per second per port. Using the "rule-of-thumb" that it takes roughly 1000 packets per second for every 106 bits per second of line rate, an OC-192 line requires routing lookups per second; well above current router capabilities. One limitation of router performance is the route lookup mechanism. IP routing requires that a router perform a longest-prefix-match address lookup for each incoming datagram in order to determine the datagram's next hop. In this paper, we present a route lookup mechanism that when implemented in a pipelined fashion in hardware, can achieve one route lookup every memory access. With current 50ns DRAM, this corresponds to approximately packets per second; much faster than current commercially available routing lookup schemes. We also present novel schemes for performing qu...

Pankaj Gupta, Steven Lin, Nick McKeown

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