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New Member

Is CEF a default switching path on cisco routers?

I read an article (not cisco authorised) that said, "CEF is enabled at global level, but disabled at interface level on cisco routers".

Isn't the Fast-Switching the default Switching path on all routers?

And as I know if CEF is not enabled on all interfaces (no ip route-cache cef) it can't form the adjancency table and can't do its job.

Am I wrong?

Thank you.

4 REPLIES

Re: Is CEF a default switching path on cisco routers?

You are correct, fast-switching is the default switching path on Cisco routers.

You have to enable CEF global, with the command ip cef. Once enabled, CEF becomes the preffered switching path.

Cheers

Gold

Re: Is CEF a default switching path on cisco routers?

CEF is the default switching method as of 12.0--in fact, fast switching doesn't even exist in the unicast path in more recent images.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800ca6c7.html

Might be of help here.

:-)

Russ.W

New Member

Re: Is CEF a default switching path on cisco routers?

It writes that the default switching path is CEF after 12.0 releases, but I tested in my test routers, I erased startup-config and when it loaded the CEF was not running.

Router#show ip cef

%CEF not running

Prefix Next Hop Interface

Router#show version

Cisco Internetwork Operating System Software

IOS (tm) 3600 Software (C3640-JK8S-M), Version 12.2(17), RELEASE SOFTWARE (fc3)

Copyright (c) 1986-2003 by cisco Systems, Inc.

Compiled Thu 15-May-03 17:03 by srani

and can you explain me "CEF is enabled at global level, but disabled on interface level by default on cisco routers"

Thank You very much

Gold

Re: Is CEF a default switching path on cisco routers?

The 3600 was not available at the time that document was released--you'll have to go into later code for CEF to be the default, probably the T train or the S train, I would think.

As for CEF being enabled by default globally, and not the default at the interface level, I don't know of any release where that is true. When I look at the 7200's and 2600's I have in the lab, they all show cef running by default, at the global and interface levels.

Russ.W

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