[c-nsp] mac flap

[harbor235]

I hope someone has seen something like this:

 %SW_MATM-4-MACFLAP_NOTIF: Host 0000.0000.0000 in vlan 111 is flapping
between port Fa0/15 and port Fa0/8


Fa0/15 and F0/8 are server ports,the servers connected to the ports are
sending Ethernet frames destined to the all zero's mac address.
What is it DHCP? BOOTP? It is isolated to three ports only, if I move one
of the affected servers to a different port the behavior follows.
Unconfigured virtualized servers may broadcast to the all zeros?
Misconfiguration on the server? network boot enabled? Not likely
since a static IP is assigned and the servers are active, vmware, vbox, etc
.. not installed

My logs are filed with these messages, I could disable the mac change
notification but i would like to understand what is going on.

tcpdump:

23:22:54.620303 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46
23:22:55.628724 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 162
23:22:59.449619 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46
23:23:00.579483 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46
23:23:02.635356 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46
23:23:05.362423 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46
23:23:05.962898 00:00:00:00:00:00 > 00:00:00:00:00:00 Null Information,
send seq 0, rcv seq 0, Flags [Command], length 46



thanks in advance,

Mike