Solving NIC Team Problems in a Hyper-V VM

Q: What can I do about a NIC team in a virtual machine on Hyper-V showing a failure in the virtual machine with a reason of media disconnected?

A. NIC teaming is supported within a Hyper-V virtual machine (VM) running on Windows Server 2012, with up to two virtual network adapters in a team.

Two possible causes could occur for a failure in a team (provided you're sure there isn't a real failure in the network). First, to use NIC teaming in a Hyper-V VM, you must have configured the adapters on the VM configuration to allow teaming.

This is done in one of two ways. In the VM configuration for each network adapter, under the Advanced Features, ensure the Enable this network adapter to be part of a team in the guest operating system option is selected under NIC Teaming (see screen shot).

Alternatively, you can configure this by using Windows PowerShell, with the command

Set-VMNetworkAdapter -VMName  -AllowTeaming On

If this has been configured, then the next possible cause is that the two virtual network adapters are connected to the same external network switch, which isn't allowed.

Guest teamed virtual NICs must be connected to different external switches. Connecting them to the same external switch would introduce a single point of failure and defeat the point of the team.