[36576] in North American Network Operators' Group
RE: gigabit router (was Re: Getting a "portable" /19 or /20)
daemon@ATHENA.MIT.EDU (alex@yuriev.com)
Tue Apr 10 22:43:44 2001
Date: Tue, 10 Apr 2001 20:56:05 -0400 (EDT)
From: <alex@yuriev.com>
To: David Schwartz <davids@webmaster.com>
Cc: nanog@merit.edu
In-Reply-To: <NCBBLIEPOCNJOAEKBEAKGEJGOEAA.davids@webmaster.com>
Message-ID: <Pine.LNX.3.96.1010410205011.6377R-100000@cathy.uuworld.com>
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Errors-To: owner-nanog-outgoing@merit.edu
> > CEF should be called Customer Enrangement Feature. It is a very very very
> > bad idea to have linecards be anything else than forwarders. They
> > should not
> > make any intelligent routing decisions. There should not be a
> > tons of copies
> > of routing table on line cards. That is what creates problems.
> CEF allows linecards to be forwarders. They don't make any routing
> decisions, they just forward packets according to a routing table. (Routing
> = deciding where packets should go, ie building a routing table. Forwarding
> = sending packets to their destination, ie using a routing table.)
Excellent idea. Why, pray tell, then there is such things as "show cef
drop" and "show cef not-cef-switched"?
> The reality is that having only one copy of the routing table
> creates an inevitable bottleneck.
Wrong answer. Routing table != forwarding table
> For the same reasons this won't work on a regional network, it won't work
> on a single router if the router is sufficiently complex.
Wrong answer again. Routing view != forwarding table
> The same techniques that work to scale the Internet as a whole work inside
> a box.
Wrong answer again.
> Why do you think central fowarding is superior to distributed forwarding?
Because you will have consistency problem. You are nearly 100% guaranteed to
have them.
> DS
Alex
