MS has changed the way they send out a gratuitous ARP with Windows 2008. Some of our routers appear to be ignoring this new method and others recognise it.
If you add a second IP address to a NIC with Windows 2003, the routers will update the MAC address. If you do the same thing with a Windows 2008 machine some routers will update the ARP table and others seem to ignore this change.
This is very important in a High Availability scenario where you may move an IP address between two servers on the same subnet.
We have two 6509eCisco routers and one 6509 in the same datacenter. One of these routers appears to ignore the change of the IP address from one node to another.
What can cause some routers to update their ARP cache and others to ignore the new type gratuitous ARP broadcast?