IPStash: a Power-Efficient Memory Architecture for IP-lookup

Abstract—High-speed routers often use commodity, fully-associative, TCAMs (Ternary Content Addressable Memories) to perform packet classification and routing (IP lookup). We propose a memory architecture called IPStash to act as a TCAM replacement, offering at the same time, better functionality, higher performance, and significant power savings. The premise of our work is that full associativity is not necessary for IP lookup. Rather, in this paper, we show that the required associativity is simply a function of the routing table size. We propose a memory architecture similar to set-associative caches but enhanced with mechanisms to facilitate IP lookup and in particular longest prefix match.To perform longest prefix match efficiently in a set-associative array we restrict routing table prefixes to a small number of lengths using a controlled prefix expansion technique. Since this inflates the routing tables we use pruning techniques and skewed associativity to increase the effectiv...

• Type: Conference
• Year: 2003
• Where: MICRO
• Authors: Stefanos Kaxiras, Georgios Keramidas
• Keywords: Associativity, Hardware, IP Lookup, MICRO 2003, Routing Tables