topic Re: How to disable CEF on ISR4321? in Network Management

How to disable CEF on ISR4321?

xidasd — Wed, 03 Mar 2021 08:06:27 GMT

Hello, I need to disable CEF on ISR4321 to capture CEF forwarded packet that isn't captured by "debug" command.

Is there any way to disable CEF on ISR4321? "no ip cef" or "no ip route-cache cef" is not work for ISR4321 router.

or Is there any way to capture CEF forwarded packet by "debug" command?

Re: How to disable CEF on ISR4321?

marce1000 — Wed, 03 Mar 2021 08:53:25 GMT

>... "no ip cef" or "no ip route-cache cef" is not work for ISR4321 router.

- Provide an operator log with a visual trail of commands tried and returning errors, that could be a screenshot or an ascii log from a vty-session (e.g.)

Re: How to disable CEF on ISR4321?

xidasd — Thu, 04 Mar 2021 00:06:31 GMT

Thank you for reply.

Here's error log of command tried before.

TEST-R(config)#no ip cef

% Incomplete command.

TEST-R(config)#no ip route-cache cef
^% Invalid input detected at '^' marker.

TEST-R(config)#int g0/0/1
TEST-R(config-if)#no ip cef
% Incomplete command.

TEST-R(config-if)#no ip route-cache cef
%ip route-cache cef cannot be disabled on this platform

I don't know I understand what you reply exactly because I'm new to cisco device and not good at english. If this is not exact thing, please point me out. Thank you

Re: How to disable CEF on ISR4321?

georgehewittuk1 — Thu, 04 Mar 2021 02:49:34 GMT

Hiya, what are you trying to achieve by doing this? I maybe wrong but some platforms I don't think you can disable cef.

If you are trying to debug a packet flow the ios xe packet tracer is great to see how handled by engine. https://www.cisco.com/c/en/us/support/docs/content-networking/adaptive-session-redundancy-asr/117858-technote-asr-00.html

Re: How to disable CEF on ISR4321?

xidasd — Thu, 04 Mar 2021 04:48:11 GMT

Thank you for reply

Yes, I just have checked that it is impossible to disable CEF in ISR4000 series router.

I can't tell you in detail, but since it is some kind of assessment process by using "debug icmp", I must do that. I think the assessment publisher used 2900 series router that disabling CEF does works for when made it. Is it completely impossible to capture by doing this?