STP not Blocking port

[NETAD]

Hello,

we are having a problem with spanning tree, it is not blocking a port in the configuration which is causing a loop and we are getting the fallowing error on our switches.

1105089: Feb 21 22:31:34.937: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:0C:9F:F0:2A in vlan 42 is moving from port Te2/1 to port Te2/5

1105087: Feb 21 22:31:34.897: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:0C:9F:F0:2A in vlan 42 is moving from port Te2/5 to port Te2/1

1105094: Feb 21 22:31:34.953: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:0C:9F:F0:2A in vlan 42 is moving from port Te2/1 to port Te2/5

1105090: Feb 21 22:31:34.937: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:0C:9F:F0:2A in vlan 42 is moving from port Te2/5 to port Te2/1

I created a test vlan and extended across 4 switch and none of the ports are getting blocked.

VLAN 1202 active configuration on our production environment

VLAN 99 test environment

Can someone assist in troubleshooting this issue we’re having?

thanks 

[Cristian Matei]

Hi,

    You sure there are no other switches in the layer 2 domain? I see the MAC flapping between Te2/1 and Te2/5, but port Te2/5 does not show up on your diagram. You might also have some misconfiguration, post the configs.

Regards,

Cristian Matei.