Command:

ip cef


Mode:

Switch(config)#


Syntax:

ip cef [distributed]
no ip cef [distributed]

 

Syntax Description:

distributed (Optional) Enables distributed CEF (dCEF) operation. Distributes CEF information to line cards. Line cards perform express forwarding.

 

Command Description:

To enable Cisco Express Forwarding (CEF) on the Route Processor card, use the ip cef command in global configuration mode. To disable CEF, use the no form of this command.

CEF is disabled by default, excluding these platforms:


CEF is enabled on the Cisco 7100 series router.
CEF is enabled on the Cisco 7500 series Internet router.
Distributed CEF is enabled on the Cisco 6500 series router
Distributed CEF is enabled on the Cisco 12000 series Internet router.

This command is not available on the Cisco 12000 series because that router series operates only in dCEF mode.

CEF is advanced Layer 3 IP switching technology. CEF optimizes network performance and scalability for networks with dynamic, topologically dispersed traffic patterns, such as those associated with web-based applications and interactive sessions.

If you enable CEF and then create an access list that uses the log keyword, the packets that match the access list are not CEF switched. They are fast switched. Logging disables CEF.


Example:

The following example enables standard CEF operation:

Switch(config)#ip cef 

The following example enables dCEF operation:

Switch(config)#ip cef distributed 



Misconceptions:

None


Related Commands:

None

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