TCAM organization for IPv6 address lookup

Majority of the IPv6 prefixes are 48 to 64 bits long. Conventional approach that configures the TCAM array to use 144-bit words to store IPv6 prefixes has a rather low space efficiency. Because of the limited number of I/O pins, an 128-bit IPv6 address has to be entered to the TCAM in 2 steps. If the longest matching prefix is only up to 64 bits, it may not be necessary to process the second half of the IP address. In this paper, we propose a two-level routing table organization in TCAM that can reduce the space requirement and speed up the lookup time by 40% or more. Our method is compatible with commercially available TCAM devices.