We have been using pairs of Windows Server 2003 configured to Network Load Balance using the MS NLM thing in IGMP Multicast mode. We have several farms that have both nodes connected to the same 3560 (in the same VLAN as well of course) and have no problems. However, when we move ONE of the nodes in a farm to another 3560, the NLB nodes do not see each other (both converge as DEFAULT). All of these 3560s are uplinked to a single 6500, and again everything in this server world is in the same VLAN. Has anybody else seen this behavior ? I've been looking at packet captures and trying various static MAC address entries, but can't get it to work. Any help or ideas would be greatly appreciated.