[c-nsp] spanning-tree flaps with BVI routed interface

[Brian]

I have a 2811 and a 5350 both multihomed to two 4507 core routers.  Each
router is configured with a BVI to provide redundancy to the core.  However,
I continually see a host flapping message in the core router every 30
seconds.

Mar  9 15:18:38 Central: %C4K_EBM-4-HOSTFLAPPING: Host 00:1A:2F:C7:2E:50 in
vlan 697 is flapping between port Gi7/31 and port Po27
Mar  9 15:19:08 Central: %C4K_EBM-4-HOSTFLAPPING: Host 00:1A:2F:C7:2E:50 in
vlan 697 is flapping between port Gi7/31 and port Po27
Mar  9 15:19:38 Central: %C4K_EBM-4-HOSTFLAPPING: Host 00:1A:2F:C7:2E:50 in
vlan 697 is flapping between port Gi7/31 and port Po27

Gi7/31 is the physical connection on the 1st 4507 and Po27 is the link
between the 4507's.  The 2nd 4507 has similar log messages.


The config of the 2811 is as follows:


interface FastEthernet0/0
 no ip address
 duplex full
 speed 100
 bridge-group 1

interface FastEthernet0/1
 no ip address
 duplex full
 speed 100
 bridge-group 1

interface BVI1
 ip address 204.X.X.X 255.255.255.224

bridge 1 protocol ieee
bridge 1 route ip


I believe spanning-tree should block one of the ports and keep the other
port in a forwarding state.  It seems to be bouncing back and forth.  Any
ideas as to what could be causing this behavior and/or how to correct it?

Thanks,
Brian