Re: CEF n Distributed CEF

Hi CCIE Kid

In regular (central) CEF, the RP does the job, and in distributed CEF, the
line card does the job (the CEF workload is distributed):

*CEF can be enabled in one of two modes:*

Central CEF Mode
Distributed CEF Mode

*Central CEF Mode*
When CEF mode is enabled, the CEF FIB and adjacency tables reside on the
route processor, and the route processor performs the express forwarding.
You can use CEF mode when line cards are not available for CEF switching or
when you need to use features not compatible with distributed CEF switching.

*Distributed CEF Mode:*
When dCEF is enabled, line cards, such as VIP line cards or GSR line cards,
maintain an identical copy of the FIB and adjacency tables. The line cards
perform the express forwarding between port adapters, relieving the RSP of
involvement in the switching operation.
dCEF uses an Inter Process Communication (IPC) mechanism to ensure
synchronization of FIBs and adjacency tables on the route processor and line
cards.

http://www.cisco.com/en/US/docs/ios/ipswitch/configuration/guide/cef_overview
.html

So the difference between the two is easy to understand, but I recommend
reading up on the details and getting to know the commands involving CEF.
And you should really understand the difference between process switching,
fasts witching, flow-based switching and CEF.

HTH

Regards
Atle Hardarson

On Wed, Sep 21, 2011 at 7:19 PM, CCIE KID <eliteccie_at_gmail.com> wrote:

> Hi fellas,
>
> Can anyone point me the difference between CEF n Distributed CEF. In which
> cases one would enable distributed CEF against normal CEF.
>
> --
> With Warmest Regards,
>
> CCIE KID
> CCIE#29993 (Security)
>
>
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Received on Wed Sep 21 2011 - 21:05:25 ART