High Speed Route Lookup for Variable-Length IP Address

Abstract

Since the advent of the Internet, IP addresses have been the core of the Internet. However, with the rapid development of the Internet in recent years, IP addresses are facing more and more problems, such as address exhaustion, low packet efficiency and low flexibility. The reason is that IP addresses use a fixed-length design and lack extensibility. The New IP network architecture and addressing method were born to solve these problems. Based on this architecture, the addressing scheme adopts variable-length and structured addresses. The address space can be smoothly expanded according to the network scale without modifying the old network address configuration. But there are some challenges about New IP, and the greatest one lies in the route lookup of variable-length IP addresses. Content Addressable Memories (CAMs) are widely used in high speed routers to find matching routes for packets in a routing table. They enable the longest prefix matching on fixed-length addresses to be completed in a single clock cycle. However, they can not deal with New IP prefixes with variable lengths directly. In this paper, we propose a mechanism using Binary CAMs (BCAMs) and Ternary CAMs (TCAMs) to efficiently store New IP addresses and complete a route lookup in constant time. Moreover, we combine the hash scheme and CAMs matching scheme to shorten the extremely long New IP addresses and reduce TCAM storage space consumption. The simulation results show that our mechanism can provide high speed route lookup with low power consumption.