Multi-zone caches for accelerating IP routing table lookups

Abstract

The key steps in routing an IP packet are: determining which outgoing interface should be used to forward the packet, switching the packet to that interface, and scheduling the packet for transmission on the outgoing link. The first step requires comparing the destination address to those in a routing table to find the best match. This step can be accelerated by caching the results of recent lookups, and referencing the cache instead of recomputing the lookup. We document a new cache organization especially suited to the address reference behavior of IP traffic, and report performance results for caches based on this new design approach. The new cache design reported shows miss ratios approximately one-half those of conventional caches.