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Re: And Now for Something Completely Different (was Re: IPv6 news)

  • From: Per Heldal
  • Date: Mon Oct 17 12:21:41 2005

man, 17,.10.2005 kl. 07.25 -0700, skrev Fred Baker:
> is that anything like using, in Cisco terms, a "fast-switching cache"  
> vs a "FIB"?

I'll bite as I wrote the paragraph you're quoting; 

Actually, hanging on to the old concepts may be more confusing than
trying to look at it in completely new ways.

Imagine a situation with no access to any means of direct communication
(phone etc). You've got a message to deliver to some person, and have no
idea where to find that person. Chances are there's a group of people
nearby you can ask. They may know how to find the one you're looking
for. If not they may know others they can ask on your behalf. Several
iterations later the person is located and you've established a path
through which you can pass the information you wanted.

Translated into cisco terms this mean that the FIB is just a partial
routing database, enough to start the search and otherwise handle
communications in the neighborhood (no more than X router-hops, maybe
AS-hops away). When the destination is located you keep that information
for a while in case there are more packets going to the same place,
similar to what you do with traditional route-cache.

> On Oct 17, 2005, at 6:47 AM, Mikael Abrahamsson wrote:
> >> Well, let's try to turn the problem on its head and see if thats  
> >> clearer; Imagine an internet where only your closest neighbors  
> >> know you exist. The rest of the internet knows nothing about you,  
> >> except there are mechanisms that let them "track you down" when  
> >> necessary. That is very different from today's full-routing-table.