nanog mailing list archives

RE: gigabit router (was Re: Getting a "portable" /19 or /20)


From: "David Schwartz" <davids () webmaster com>
Date: Tue, 10 Apr 2001 18:48:53 -0700



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.

Alex

        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.)

        The reality is that having only one copy of the routing table creates an
inevitable bottleneck. 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. The same techniques that work to scale the Internet as a whole work
inside a box.

        Why do you think central fowarding is superior to distributed forwarding?

        DS



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