One directional CDP

[tim.chan]

We have a 5505 workgroup switch trunked to two 5509 core switches. The workgroup switch sees CDP from the core switches, but neither core switch sees the workgroup one. Configs look good because we have the exact same setup as other workgroup switches going to the same cores. Please advise. Thanks! -Tim

[KONSTANTIN FEDOROV]

Hello

First confige udlp on the switch and check results.

[matt.alvord]

Tim,

First things first. Have you ensured that there are no layer 1 issues? Are these fiber trunk ports? My inital thoughts are that only one strand is passing traffic. In this case the transmit pair on the WKGRP switch is not functional. Obviously, the receive is working correctly. You can run a debug or even "show cdp status". This should allow you determine if you are transmitting and receiving cdp adverts. Another thing to check for is UDLD and your trunk negotiation. If you are running UDLD you should never have auto trunk ports or you will have interesting issues. Maybe just like this one:) Are there link lights on both ends or only on the WKGRP switch? You may just have a stuck port. Check the physical probs first then UDLD and CDP.

[tim.chan]

Thanks for the suggestions. I will try UDLD.

Here are some facts:

1. 5509 does not support DEBUG commands nor

"CDP status".

2. User traffic is not affected. Management is

working fine. It seems that only CDP is affected.

3. Trunk ports running 100BaseFX @ Full duplex.

[matt.alvord]

No debug on 5500 :) Can you tell I'm still living in an IOS world?

When I mentioned UDLD and auto-negotiation I was refering to the negotiation of the trunk encapsulation (ISL/802.1Q) not the speed/duplex.

If the physical stuff checks out and all other traffic is fine, I would assume that CDP adverts would be received at least from one of the core switches...eh, weird. It's my understanding that CDP is enabled by default on all ports. You may want to double-check, though.

Do you have a protocol analyser? FUN STUFF....

[tim.chan]

CDP enabled on all ports. Running ISL on the trunk lines. Cisco TAC wants to swap out the Supervisor card. I'll let ya'll know if this makes any difference.

[tim.chan]

After swapping out the sup card, the core switches started seeing the CDP packets from the workgroup switch. Thanks! -Tim