I have a server that has three physical adapters. Where it sits now there is only one link so only one NIC is on the physical network.

My question is with Server 2012 R2 Hyper-V. Can I create an internal switch and route it out the physical network adapter, or create an external switch on an unused network adapter and route it out the connected one?

Each External Virtual Network must be bound to a physical NIC or NIC team as one of its interfaces. (the other interfaces are virtual NICs that the VMs (or host) can connect to.

Hyper-V does no strange routing.  The virtual switch handles it all between the VM and the LAN.

Just create external switch on the connected adapter and be sure Allow Management OS to use this network is checked (-AllowManagementOS $true for powershell cmdlet). Note that if you need you can assign different VLANs for each VM and management OS.

This will allow both management OS and all Virtual machines to use the single physical adapter. No need for other two and they can be disabled.

Internal network adapter is providing network between the virtual machines and the host operating system only, so it will not help you without additional routing configuration (but this doesn't make sense). Attaching external adapter to non-connecting NIC and route it to the connected one will not work.

Kind regards,

Hristo Voyvodov

If you want to route between NICs on different network subnets, you will need to set up a system that is connected to both networks and install some sort of routing software.  Hyper-V, as Brian stated, does not do any routing.  Windows Server comes with RRAS which can be configured to handle routing, but it is not installed by default.

But, as Hristo says, if you simply want the VMs to share the same physical connection that the host is using, create an external virtual switch that allows the host OS to share.

Already given in the previous replies, the Hyper-V switching is only providing with an intermediate layer. In order to get an easier understanding of it all, enabling a virtual switch on top of a physical NIC (or NIC team) is actually creating a switch. The switch in question has an uplink which is connected to the physical interface. By enabling for the management OS to be allowed to connect to the switch, this is virtually creating a virtual NIC in the management OS with the same name as the virtual switch. That NIC is connected to virtual switch and inherits the network configuration of the physical NIC to which the switch uplink is connected.

The effect of this is that if utilising more than one NIC on a server, the best way of simplifying interface aggregation and getting an embryo of a failover solution, is to team all the NICs that are connected to the same network in a "Switch Independent" teaming configuration. This is, given that the different cables are connected to different switches. This will present a single teamed interface to the management OS and then that interface can be utilized to create a virtual switch.

Apart from creating an external switch, you can also create internal switches if there is a need for keeping IP addressing inside of the Hyper-V host but to also have a single VM to provide for routing if the routing capabilities is what you are asking for specifically.

This answer is provided as is and based on my personal understanding of your current situation. If something in this mapping doesn't apply to your specific situation, there may or may not be discrepancies in how to apply the potential solution provided above.

Yours
Richard Johansson
Hyper-V Specialist Consultant

Hi Sir,

>>Can I create an internal switch and route it out the physical network adapter, or create an external switch on an unused network adapter and route it out the connected one?

If you want to get internet access for VMs , you can create internal Vswitch and  use ICS on hyper-v host :

https://social.technet.microsoft.com/Forums/en-US/d380e4c3-a9c0-483f-8fd9-11962b1f486c/enable-virtual-machine-to-access-internet-with-ics?forum=winserverhyperv

 Best Regards,

Elton Ji