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How to disable CEF in C3550

What is the command to disable CEF in Catalyst 3550 MLS.

Thanks in advance.


Re: How to disable CEF in C3550


"You can disable CEF on an interface by using the no ip route-cache cef interface configuration command"


for details.

I think you should be able to disable CEF completely by

no ip cef

global configuration command (but not documented in Command Reference Guide).




Re: How to disable CEF in C3550

CEF is enabled globally by default. If for some reason it is disabled, you can re-enable it by using the "ip cef" global configuration command.

To disable CEF, use the no form of this command:

no ip cef

The default configuration, which is recommended, is CEF enabled on all Layer 3 interfaces. You can disable CEF on a particular interface by using the "no ip route-cache cef" interface configuration command; you can enable CEF on an interface by using the "ip route-cache cef" interface configuration command.

Of course, enabling or disabling on an interface-by-interface basis is meaningful only if CEF is enabled globally. If CEF is disabled, then what you do on the interfaces doesn't matter.

Use the "show ip cef" command to check the results of your efforts.

Cisco Express Forwarding (CEF) is a Layer 3 IP switching technology used to optimizes network performance. CEF implements an advanced IP look-up and forwarding algorithm to deliver maximum Layer 3 switching performance.

In the Catalyst 3550 switch, the hardware uses CEF to achieve Gigabit speed line rate IP traffic. Disabling CEF will affect your Layer 3 IP forwarding speed; whether you notice or not depends on how much you were using it in the first place.

Hope this helps.

EDITED TO ADD: Most of what I posted here about the 3550 is found at the link that Milan referenced above. The part about disabling CEF globally is from documentation for the 6500, which also uses CEF to achieve line-speed IP forwarding. It appears to have been omitted from the 3550 documentation.

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