Debugging ping on Switch/Router

[JohnTylerPearce]

Hey, I was trying to debug some ping packets but I am having a diffucult time. I've been able to do this before but for some reason it's not working.

I have done the following configuration.

access-list 111 permit icmp host a.a.a.a host z.z.z.z

debug ip packet 111 detail

Now, I know for a fact that ping connectivity works, but I just can't see the debugs of it. I'm pretty sure I'm typing the correct

debug configuration commands?

I put the configuration on the core switch of the destination I'm trying to ping.

[viswamin]

CAn you check the ACL counter hits ? do you see the counter increase ?

just curious to know if the ACL is working because the debug is based on the ACL.

-Vijay

[JohnTylerPearce]

When I do a 'show access-list 111' I don't see any hits. All I see is the ACL statement.

[cadet alain · Accepted solution]

Hi,

you won't see any debug for packets that are not processed switched( not locally generated or destined to the device you have the debug going on.

and secondly by default if you're connected to a terminal line you must enable terminal monitor and send the logs to the terminal with the logging monitor debug command.

Please rate if helpful.

Regards.

Alain

[JohnTylerPearce]

Cadet, is this because the core switch is technically a pass-through router so to speak, and doesn't actually generate the packet itself?

[JohnTylerPearce]

I think I know what you mean. Technically you can only debug the source and destination because they actually process this via software and not hardware. The intermediate devics technically use whatever switching method via hardware *unless process switch* and you can't debug hardware switching?

[rsimoni]

that is correct! switches handle transit traffic in hw, while debugs are configured at software level in IOS which will never see the transit traffic pass.

On the contrary if you ping with options you will see the packets showing up in debugs as IP options are not handled in hardware but in software.

regards,

Riccardo