To determine how to forward a packet, an Internet router must perform routing lookup on the destination IP address. Since the adoption of classless interdomain routing in 1993, routing an incoming packet requires that the router find the longest routing prefix that matches the destination IP address. Researchers have proposed various software-based schemes to accelerate the lookup function. However, all of these approaches require at least four to six memory accesses. With the requirement for higher throughput, the latency and bandwidth of modern memory architecture severely limit the number of memory accesses a system designer can afford. Clearly, the software-based solutions do not easily scale up to 10-Gbps processing and beyond.
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