Can't disable CEF on SUP2

May 01, 2007 4 Replies

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dennis 19 years ago

Hi all,

I have the following problem.

A customer want to disable cef on a cat6509 with SUP2A and IOS

12.1(27b)E1

Disabling CEF is not possible: ===========================================

router03(config)#no ip cef distri

%Cannot disable CEF on this platform

router03(config)#no ip cef ?

accounting Enable CEF accounting

distributed Distributed Cisco Express Forwarding

linecard CEF linecard commands

load-sharing Load sharing

table Set CEF forwarding table characteristics

traffic-statistics Enable collection of traffic statistics ================================================== also when try to disable only CEF

router03(config)#no ip cef

% Incomplete command.

===============================================##

Is this platform dependent ?

thx dennis

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NetExpert 19 years ago

Hi Dennis,

Yes, disabling CEF is platform dependent. You can disable it on platform that are switching packets in software like 2600 or 7500.

As far as I know on Cat6500, CEF is done in hardware. So disabling it would just kill the box. That?s why you cannot disable it.

NetExpert

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dennis 19 years ago

Hi,

thanks for the > Hi Dennis,

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Thrill5 19 years ago

Disabling CEF on ANY platform is like buying a Corvette, and then disabling

7 of the cylinders because you want better gas mileage. Neither makes much sense. Disabling CEF reduces you forwarding rate by at least a factor of 10, and increases latency through the device by a similar factor. The reason "ip accounting" doesn't work with CEF is because it has been superseded by "netflow". Netflow is supported with CEF and on all of the high end platforms has only a very small performance penalty, and that is only seen when nearing the peak capacity of the device. There are several free netflow collectors and accounting packages available.

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dennis 19 years ago

Thanks Scott for your detailed explanation.... I also tell our customer it's like removing five of the six cylinders from a porsche..because we are in germany..;-)) But he tell me he will wait before implementing netflow...so first he _must_ disalble CEF. So I tell him that he can disable cef with the global command "no ip cef"...but this doesn't work.. For my understand is a "security" mechanism on the this platform !?

rgds dennis

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