Re: Disable CEF in 3560

Hi All,

theoretically there is a "trick" that may effectively "disable" CEF
for select traffic. You just need to configure an access-list matching
the traffic you want to process-switch and specifying the "log" option
and apply it to an IP interface. In effect all matching traffic will
be punted to RP, though I noticed inconsistent behavior across
different switches/IOS images, depending on the setting for ACL
logging rate-limits. Of course, this is NOT something you would ever
want in production, unles you know what you're doing :)

ex:
access-list 100 permit ip any any log
!
interface Vlan 10
 ip access-group 100 in

HTH,

-- 
Petr Lapukhov, petr_at_INE.com
CCIE #16379 (R&S/Security/SP/Voice)
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2009/9/11 Steve Lyons <charter21p5_at_gmail.com>:
> I am reading older threads and decided to respond to this one. You cannot
> disable CEF on switching platforms. You can disable CEF on routing
> platforms. Process switching can occur on both routers and swtiches however
> if CEF is enabled and data packets not intended for the device are being
> process switched then it should be investigated. You can tell if traffic is
> being process switched by using "show ip traffic" Also if you type "show
> proc cpu" and ip input is consuming high cpu cycles then you should
> investigate into why.
>
> Steve Lyons
>
>
>
> On Thu, May 21, 2009 at 8:36 AM, Pavel Bykov <slidersv_at_gmail.com> wrote:
>
>> Hello Anbu.
>> To simplify, since 3560 is a hardware platform, the only way to stop cef is
>> with a screwdriver and a hammer.
>> 3560 does not have chips and ASICs for the other forms of forwarding.
>> There are special cases, like IP options that have to be processed by CPU
>> and so on, but it's done using CEF punt actions.
>>
>> On Thu, May 21, 2009 at 12:40 PM, Anbu <ksanpu_at_gmail.com> wrote:
>>
>> > Hi all
>> >        Here i have an issue in CEF configured on 3560 , i hanve
>> configured
>> > two switches ( 3560 & 3750) to check CEF. both switches connected by a L3
>> > link and CEF  enabled.
>> > then i have tried to stop cef , but cannot stop in config mode as it is
>> > 3560
>> >
>> > SW1(config)#no ip cef distributed
>> > %Cannot disable CEF on this platform
>> >
>> >  so have stoped all the interfaces
>> >
>> > SW1(config-if)#no ip route-cache cef
>> >
>> > all the cef entries are there even i have cleared all , and restart the
>> > switch.
>> >
>> > *All this issues are in 3560 only*
>> >
>> > So i am expecting advice to overcome that.
>> >
>> > Regards,
>> > Anbu
>> >
>> >
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>> >
>> >
>> >
>> >
>> >
>>
>>
>> --
>> Pavel Bykov
>> ----------------
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