> Would you agree that any type of 'route caching' wouldn't scale
> well on a backbone router? I think that you have to have full
> table with all best paths on a forwarding engine. (I might be
> off topic cause it's not about some today's HW.) The penalty
> for doing multiple lookups can be minimal when it'll be done in
> ASIC.
Well, from what I hear there are good reasons why cisco is
implementing use of a distributed forwarding table for use in their
high-end gear (known as "Cisco Express Forwarding"/CEF or "FIB
switching"). I guess some of the reasons are that cache invalidations
cost too much because the main CPU can be a bottleneck in forwarding
decisions. I hear that in the Cisco 12000 boxes the main CPU can't do
any packet forwarding at all; all the forwarding decisions have to be
taken by the "line cards".
- Håvard
This archive was generated by hypermail 2b29 : Sun Aug 04 2002 - 04:13:15 EDT