[c-nsp] Mac address flapping..

[Jonathan Lassoff]

Excerpts from James Ashton's message of Fri Jul 10 08:56:40 -0700 2009:
> 
>        %MAC_MOVE-SP-4-NOTIF: Host 00d0.009e.2400 in vlan 42 is flapping between
> port Po1 and port Gi1/7
> 
> I see about 20 of these for this one vlan each minute.
> Spanning tree is not reconverging.  It hasn't had a topology change in over 48
> hours.
> HSRP has not changed state.
>
> 6509-b:
> VLAN0042
>   Spanning tree enabled protocol ieee
>   Root ID    Priority    24618
>              Address     00d0.00a7.f000
>              Cost        3
>              Port        1665 (Port-channel1)
>              Hello Time   2 sec  Max Age 20 sec  Forward Delay 15 sec
> 
>   Bridge ID  Priority    28714  (priority 28672 sys-id-ext 42)
>              Address     00d0.009e.2400

This is telling -- notice that one of the burned-in addresses on 6509-b
is the one from your log message.

20 times a minute?
HSRP's default hold timer is every 3 seconds -- 20 times a minute.

You also described Gi1/7 as going to 4506-b, right? I would investigate
why spanning tree isn't blocking one of the uplink ports, as it's
causing what sounds like a loop.

Perhaps check that there's something listed from a "show spanning-tree
blockedports".

Cheers,
jonathan