I have a customer network that is experiencing mac flaps between a 3750 and dlink switch. Here's what it looks like:
phones(vlan 6)==>dlink==>3750
This customer has all of their ip phones (non cisco) connected to the dlink switch on vlan 6, the dlink has an ip addr in vlan 6 and the uplink to the 3750 is set as an access port in vlan 6. I have verified that there is only a single physical connection between the dlink and the 3750. I am not running STP on the dlink. I am seeing mac flap messages on the 3750 for mac addresses directly connected to the 3750 saying they are flapping between the ports they are physically connected to and the port that connects the dlink to the 3750. somehow the 3750 is learning mac addresses of directly connected devices through the port connected to the dlink. if i look at the mac table on the dlink it shows the flapping mac addresses on the port connected to the 3750. anyone have any idea why this may be occurring?
