Is it a good idea to hardcode or force spanning-tree root in a campus environment?
I have a campus made up of four buildins supported by a 4506 core and 21 2950/2960 switches. These switches are either directly connected to the 4506 or are in daisy chained in groups of two or three back to the 4506. I have 14 VLANS supporting different areas of the campus for voice and data.
I am starting to receive error messages similar to the following...
Mar 20 14:27:01.272 CST: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:BC:1E:C5:C5 in vlan 1 is flapping between port Gi4/5 and port Gi3/2
Mar 20 14:36:02.584 CST: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:BC:1D:7A:09 in vlan 1 is flapping between port Gi3/1 and port Gi3/2
Mar 20 14:38:07.116 CST: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:BC:2A:05:0C in vlan 1 is flapping between port Gi3/2 and port Gi4/5
Mar 20 14:38:34.488 CST: %C4K_EBM-4-HOSTFLAPPING: Host 00:00:BC:1D:7A:09 in vlan 1 is flapping between port Gi3/2 and port Gi3/1
Mar 25 08:16:18.169 CST: %C4K_EBM-4-
HOSTFLAPPING: Host 00:09:6B:A5:B9:F0 in vlan 1 is flapping between port Gi3/2 and port Gi2/22
The odd thing is that none of these switches are connected together. The interfaces reported are in some cases even in differnet buildings. At first I though this was only affecting VLAN1 but it appears to be affecting the whole campus.
In talking with TAC, they are thinking this may be a spanning-tree issue and I am only seeing the symptoms. In looking further, the root is not my 4506 core. It is one of the 2960s out on the campus. They want to wait until I have another extended outage to check CPU utilization and the like to verify this theory but I do not understand the relation between that and the error message.
Would it not be a good idea to go ahead and configure the 4506 to be the root? The switch that is currently the root does have two possible paths back to the core just due to the required redundancy in that specific area of the campus.
I will get a visio diagram modified to post.