Installing Hyper-v Server 2012 R2 is easy, Creating a converged fabric too. A converged fabric (or hyper-converged fabric) is a single external vSwitch connected to a team or a net adapter, with multiple vmnet adapters to server multiple roles (Management, live migration). It’s a good approach when using 10 Gbps adapters or for a lab.

Imagine the situation if you install your server via IPMI, create your converged fabric and add the management network adapter. But there is a problem. Hyper-v uses the first IPv4 on the server to build the range of MAC addresses for the virtual machine.

  • 00:15:5D for the Microsoft IEEE identifier
  • XX:XX corresponding of the 2 last octets from the first IPv4 of the server
  • The last byte, from 00 to FF for each virtual adapter

But what happen if you don’t have any IP Address. Hyper-v will assign 00:15:5D:00:00:00. Hyper-v Server wasn’t able to create a valid range. It’s not a problem for a single server, but if you have multiple servers connected to the same network, you are in trouble, and if you use a converged fabric all your servers can have the same MAC for the management adapter.

You can change that by creating the mac address range before your converged network.

PS>Set-VMHost -MacAddressMinimum 00155D020600 -MacAddressMaximum 00155D0206FF

And it’s not a bad idea to change the default Range by using something like server ID or Serial number.

Using VMM Bare Metal deployment prevent this problem