Explain Debug Info

[CiscoBrownBelt]

I am looking for good documentation, info, videos anything explaining how to interperate all the different debugs especially debug ip packet. Any help?

Here is one thing I am getting when trying to ping directly connected devices: have default/static routes, SVIs and Sub-interface up, all allowed through trunks, etc.

IP: s=192.168.252.7 (local), d=192.168.252.1 (Vlan252), len 128, encapsulation failed

[Reza Sharifi · Accepted solution]

Not sure if there is a book or video explaining all the debug command as there are just too many of them.

As for the one you posted:

s=192.168.252.7 (local)

s is for the source, so this is the source IP which is local as well.

d=192.168.252.1 (Vlan252)

d is for the destination IP in vlan 252

len 128, encapsulation failed

And there is an issue with encapsulation.  So, you may want to make sure this vlan is added to the trunk on both sides of the link and the encapsulation is the same.

Also, have a look at this link for more info on debug commands:

https://www.cisco.com/c/en/us/support/docs/dial-access/integrated-services-digital-networks-isdn-channel-associated-signaling-cas/10374-debug.html

HTH

[CiscoBrownBelt]

I am not pruning on the trunk links, all vlans are allowed.

I don't get any debug messages after doing "debug ip packet".

Do you know the command I must enter on a Catalyst 3850 if CEF is being used if that is the reason why?

[Reza Sharifi · Accepted solution]

Debug not showing on the screen is not a CEF issue. Try command

"terminal monitor" and test again.

HTH

[CiscoBrownBelt]

Oh I thought with certain devices that are using CEF I would not to disable that.

[CiscoBrownBelt]

When pining an SVI of another switch that goes through a router, I noticed in the debug log:

*Apr 23 07:17:22.841: IP: s=192.168.252.10 (local), d=192.168.252.1 (Vlan252), l                 
en 100, encapsulation failed  

No pruning on trunks, Sub-int/SVIs all up.

Do you know what else I should look at?

[CiscoBrownBelt]

Ok so once I should down the SVI on the switch for the VLAN sub-int on the router I could not reach everything worked. Any idea why?