I am migrating from a 3750G to a 3750X. I have 20 VLAN interfaces (SVIs) on the 3750G that need moved to the 3750X. These SVIs are the default-gateways for the VLANs. I have the 3750G and the 3750X connected with a couple of interfaces that are trunked and in etherchannels. The switches are also running EIGRP with a WAN router and ASA firewall.
I have moved a couple of non-essentials SVIs by issuing a SHUT on the 3750G and adding the SVI with the same IP address to the 3750X without any issues. I have already moved the SVIs common to the router and will be moving the SVI common with the ASA at a later time.
My concern is that I have a couple of VLANs with approximately 150 virtual servers (VMware) mostly Windows 2008/12 and they will have issues with their arp cache. I have a 30 minute maintenance window to complete this operation.
One thought was not to SHUT the 3750G SVIs but give them new IP addresses and add the existing SVI IP addresses to the 3750X.
In this scenario, would a server that had the old ARP entry for the 3750G SVI send an off network packet to the 3750G and the 3750G would then forward it to the 3750X until the server learned the new MAC address of the default gateway?
Any other way to move SVis with minimal interruptions?
