"debug" output inconsistencies

Unanswered Question
Dec 8th, 2008

On any of my 2501's or 2502's, I activate "debug cdp adjacency" or "debug cdp events" shortly after booting up. I see no debug output when a new cdp neighbor comes online; neither before nor after that neighbor appears in the sh cdp neighbors command.

Also I can do a debug ip ospf events and it will notify me of every single hello packet going out. I don't consider a hello packet to be an "event." An "event" is like a Zeppelin concert or something of that magnitude.

Isn't there a way to keep something as mundane as hello traffic out of the debug output?

And, is there something wrong with the cdp facilities on these routers that they don't announce new adjacencies when they are asked to?


-- stuey

I have this problem too.
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Giuseppe Larosa Mon, 12/08/2008 - 23:03

Hello Stuey,

for OSPF the best suited command is

debug ip ospf adj

this is useful for tracing OSPF adjacencies and to see how they are made.

I confess I never used any CDP related debug, however you can perform the following test:

with the debug cdp commands active shut down a link where you have a CDP neighbor and then re-enable it.

If even so you don't see nothing they are probably unsupported.

Hope to help


CriscoSystems Tue, 12/09/2008 - 12:09

So, you're telling me it's possible for EXEC to accept the "debug cdp adj" or "debug cdp events" commands without issuing any error messages, even if those debug facilities are in fact not supported on the router?

Edison Ortiz Tue, 12/09/2008 - 12:48

Something is wrong with your debugs...

On a 2600 router..

Rack1R1#sh cdp ne

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater

Device ID Local Intrfce Holdtme Capability Platform Port ID

Rack1SW1 Fas 0/0 168 R S I WS-C3560- Fas 0/1

Rack1R1#debug cdp adjacency

CDP neighbor info debugging is on

Rack1R1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Rack1R1(config)#int f0/0


*Jan 29 00:27:58.384: CDP-AD: Interface FastEthernet0/0 going down

*Jan 29 00:27:58.388: CDP-AD: Interface FastEthernet0/0 going down


Rack1R1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

Rack1R1(config)#int f0/0

Rack1R1(config-if)#no shut



*Jan 29 00:28:19.238: CDP-AD: Interface FastEthernet0/0 coming up





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