Find the offending MAC address for bpduguard

[steven.crutchley]

I have a Cisco WS-C6509-E with IOS, connected to a hypervisor with multiple VMs on it.

The port on the 6500 that connects to the hypervisor is a trunk port and has bpduguard enabled.

One of the VMs is causing the port to go into err-disable state by send bpdus. I am trying to figure out which, from the Cisco itself. Specifically I'm trying to find that VMs MAC address.

Is this possible? I have looked at debugging with full spanning-tree debugging on but all i get is that the port goes into err-disable. It doesn't tell me what the offending MAC address is (or anything about the BPDU).

Short of stripping VLANs from the trunk until I have the culprit network (which won't actually give me the culprit device but rather, only its VLAN), I'm not sure if there is a direct command or debug to give me this information directly. Can anyone help?

[johnd2310 · Accepted solution]

Hi,

Try spanning the port and capture some traffic.

Thanks

John

[Dennis Mink]

Steven,

I'm with John on this one, your 6500's log wont reveal the offending MAC, unless you start debugging spanning tree. Your best bet is wireshark and filter your capture based on the STP protocol.

HTH

[steven.crutchley]

Hmm... I was afraid that might be the only option. I have tried to do full debugging on spanning-tree but it gives me nothing. Is there no way to look into the BPDU details without using SPAN?