Windows Server optimize

How to create an external virtual switch in Hyper-V on the Windows Server 8 Beta

For anyone with a virtualization background, Hyper-V networking may not be as intuitive as other technologies. Rickatron shows how to create an external virtual switch in this post.

If you haven’t started to tinker with the Windows Server 8 Beta, you should! I’m watching the Hyper-V features very carefully, as many capabilities are being added to the Microsoft virtualization offering with this release.

One thing that I will admit that I don’t understand as well as I do in the vSphere world is Hyper-V networking, partly because you can’t “stack” all roles on one interface like you can with ESXi. While you don’t necessarily want to do that in production, with a beta or lab situation, it is pretty common.

For Hyper-V host networking, the most common option is to create an external access virtual switch. This allows VMs on the host to access other systems on a traditional VLAN or standard switched network. Creating this type of virtual switch network in Hyper-V on the new Windows Server 8 beta is shown in Figure A:

Virtual Switch Options

Virtual Switch Options (click to enlarge)
When you do this task, you want to have a few pieces of information and specific configuration in place beforehand. Specifically, ensure that at least two network interfaces are configured and one is designated for what I’ll refer to as Host access. This would be where the Windows Server 8 system communicates to the Ethernet network. The other configuration is to have one or more interfaces designated for guest VM access. It is also imperative that each interface has a self-documenting name and that you can determine the device name (typically a driver and instance identifier) for each interface. Figure B below is an example of this configured on a Hyper-V host with three network interfaces, of which two are configured for Hyper-V guest and host networking:

Figure B

Interface driver and instance identification

Interface driver and instance identification (click to enlarge)
The final step is within the Hyper-V virtual switch manager to create the virtual switch with the specified configuration. This is another area where nomenclature and filling out the notes field will help in troubleshooting down the road and simplify the configuration when multiple virtual switches are in place. Figure C below shows this step in the Hyper-V networking configuration:
External virtual switch creation

The creation is easy; it simply takes a few steps ahead of time to ensure that the right interfaces are lined up for the right roles. It is also a good idea to ensure that no host networking (IP address and especially DNS registration) takes place on an interface that will be designated for guest VM networking with the newly created virtual switch. This will avoid any DNS issues down the road.

What tips do you use to deploy Hyper-V networking? Do you plan to implement any changes for Windows Server 8’s Hyper-V features? Share your comments below.


Rick Vanover is a software strategy specialist for Veeam Software, based in Columbus, Ohio. Rick has years of IT experience and focuses on virtualization, Windows-based server administration, and system hardware.