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.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.