I'm migrating / cloning license servers from Hyper-V to VMware, The current hyper-V MAC Addresses are not within the range and cannot be used.
Adding the mac address in the Operating System is not working.
Why not just input a custom MAC when you bring that machine over into vSphere? If you tried that and say it doesn't work, can you clarify? I've done this several times and had no problems.
To answer your question, however:
I know that within SCVVM it's possible to add a MAC Address range, is this also possible in vCenter 6 or on the host?
There are no MAC address ranges, but, based on vCenter's ID it does use that to map down the vendor portion of the MACs, but no where is there a range that's defined.
