Strange MAC Issue - MAC appears on both sides of trunk with host int shutdown

[JHarris6117]

Community,

Encountering a strange issue where a mac ending in f3a2 is supposed to be on interface gi3/47 on a 4500 switch.  We started having issues on it and shutdown the port to test further.  

Even though the port has been shutdown for 2 hours, the 4500's mac address table still shows the MAC as coming from a downstream switch's trunked interface gi1/5:

524      0090.5e13.f3a2   dynamic ip,ipx,assigned,other GigabitEthernet1/5

When connecting to the downstream switch, it shows the mac address as coming from the previous switch back across the trunk:

524    0090.5e13.f3a2    DYNAMIC     Gi1/1

Clearing mac address table on both switches at the same type causes the mac address to disappear on switch 2 for about 20 seconds, than reappears the same as above.  Also checked port security, there are no learned mac addresses.

Also, for those that think its spanning tree, very few changes have occurred on either switch:

Show spanning-tree detail | I from|exec|occurred|ieee
VLAN0024 is executing the ieee compatible Spanning Tree protocol
Number of topology changes 1 last change occurred 15w3d ago
from GigabitEthernet1/1
VLAN0524 is executing the ieee compatible Spanning Tree protocol
Number of topology changes 1 last change occurred 15w3d ago
from GigabitEthernet1/1
VLAN0770 is executing the ieee compatible Spanning Tree protocol
Number of topology changes 1 last change occurred 15w3d ago
from GigabitEthernet1/1
VLAN0772 is executing the ieee compatible Spanning Tree protocol
Number of topology changes 0 last change occurred 5w3d ago
VLAN0883 is executing the ieee compatible Spanning Tree protocol
Number of topology changes 0 last change occurred 15w3d ago

Will rate if we get to an answer,

Thanks,

Jake

[Georg Pauwen]

Hello Jake,

can you post the full MAC address ?

[JHarris6117]

Sure its posted above... 0090.5e13.f3a2

[Georg Pauwen]

Hello,

is the device (Rauland Borg Corporation by the way, a company that does medical equipment)) still physically connected to the port ? If so, try to unplug the table and then clear the MAC address table again.

If that doesn't help, try a reload of both switches...

[JHarris6117]

The device is an AV / Crestron switcher, the port is disabled and has been for 2 hours. We are going to reload the switches tonight

[Georg Pauwen]

Physically disconnect the switcher (unplug the cable) and clear the MAC address table before you do the reload...

[Daniele Giordano]

In the past I had same issue.

Was caused by a loop. A switch was connected to a device that filtered BPDU and so STP was unable to detect the loop.

I found the loop using show mac-address table dynamic on all chain of switches.

Sometime I repeated the command rapidly and continuously to see the mac move from a port to another.

Regards.

[JHarris6117]

Issue ended up being with the single vlan.  TAC rma'd the supervisor.  Even after a reboot issue didn't go away.