* Nick Hilliard:
One of the more common hardware components for performing IP address lookups is called TCAM - ternary content addressable memory. It performs a similar function to an associative array in a language like PHP, except it's implemented in hardware. It's ridiculously fast and ridiculously expensive, and because it's so expensive, router manufacturers tend not to put large quantities into their lookup engines.
Very nice explanation, thanks! Cost is probably not that much of an issue. I suspect that the bits-per-Watt number is still extremely poor for current TCAMs (data sheets do not quote them), which means that you can only use a limited number of them in parallel. Especially for IPv6, alternative implementations are probably quite competitive, such as hardware-assisted tries or hybrid schemes relying mostly on DRAM. You can also take a few shortcuts if you encode the current IPv6 addressing architecture in silicon. -- Florian Weimer <fweimer@bfk.de> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99