Re: CEF EPOCH

Thanks a lot

On Tue, Apr 20, 2010 at 1:10 PM, Kambiz Agahian <kagahian_at_ccbootcamp.com>wrote:

> Hi there,
>
> Hahaha! the famous job interview question :)
>
> If you are referring to the "epoch value" in CEF; it's 8 bits long (max
> 255) and usually demonstrates "how many times your CEF table on that box has
> been rebuild since the last reload". In fact for your FIB and adjacency
> tables it plays the role of a global revision number. A little bit confusing
> but we also have the same concept at "entry level"; for example when an
> entry gets added to your table it gets your table's global Epoch number. So
> have the global number; copy and paste on every new entry.
>
> Any CCIE value?
> NSF or the Graceful restart does need to update this number.
>
> How is it used in NSF?
> Well, after a switchover process you get new entries and they get a new
> Epoch value (simply the global one). Don't worry about the old entries
> because they get kicked out of the tables because they dont have the current
> "global" Epoch value. You see this dependency between global and entry-level
> ones?
>
> What if you hit 255?
> It loops back to 0 and not 1!
>
> Job interview question?
> Increase the Epoch value to 13 ;) - Notepad heh?!
>
>
> You may use the "clear ip cef epoch" to initiate the recreation process
> manually.
>
> This might help :
> http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.1E/native/command/reference/clear1.html#wp1039177
>
> The Cisco press book is actuall y pretty cool on this but still a bit
> confusing on how to use the global number.
> --------------------------
> Kambiz Agahian
> CCIE (R&S)
> CCSI, WAASSE, RSSSE
> Technical Instructor
> CCBOOTCAMP - Cisco Learning Solutions Partner (CLSP)
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>
> -----Original Message-----
> From: nobody_at_groupstudy.com on behalf of Bernard Steven
> Sent: Mon 4/19/2010 11:55 PM
> To: Cisco certification
> Subject: CEF EPOCH
>
> Experts ,
>
> Some thing bugging my mind for some time.
> What is Epoch ? All i know is it is a version control in the CEF table.
> Also could not find a proper document.
>
> Send a link if possible for details.
>
>
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Received on Tue Apr 20 2010 - 13:58:08 ART