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Understanding Networking with Hyper-V

With Hyper-V the world of networking is quite different than it was with Virtual Server. First to set the scene, with Windows Server 2008 installed on a system with one network adapter you will see this under Network Connections:

shot1

And your system is operating like this:

netpic1

Once you install Hyper-V and create a virtual network your system now operates like this:

netpic2

As you can see the parent partition (host operating system in Virtual Server lingo) is now using a virtual network adapter to connect to the physical network.  If you look at network connections on the parent you will now see the original network adapter and a new virtual network adapter:

shot2 shot3

The original physical network adapter now has nothing bound to it except the Microsoft Virtual Network Switch Protocol.  The virtual network adapter now has all of the standard protocols and services bound to it instead.

Some interesting things to note here:

  • The virtual network adapter that appears under Network Connections will have the same name as the virtual network switch it is associated with.

  • It is possible to create an 'Internal' virtual network - which will expose a virtual network adapter to the parent partition without needing to have a physical network adapter associated with it.

  • Unlike with Virtual Server, Hyper-V only binds the virtual network service to a physical network adapter when a virtual switch is associated with the physical network adapter in question.  The advantage of this is that you avoid the performance overhead involved with having this service enabled on network adapters that are not associated with virtual network switches, the downside is that it means that networking gets disrupted on the network adapter in question when a virtual network switch gets created or deleted.

Cheers,
Ben

Published Tuesday, January 08, 2008 11:39 PM by Virtual PC Guy
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Comments

Wednesday, January 09, 2008 10:51 AM by Michael Dragone

# re: Understanding Networking with Hyper-V

Ben, shots 2 & 3 look the same to me. Did I miss something?

Wednesday, January 09, 2008 4:31 PM by Alan

# re: Understanding Networking with Hyper-V

I think image 2 & 3 are the same? is this right?

Friday, January 11, 2008 9:23 AM by BrentP

# re: Understanding Networking with Hyper-V

I have an issue that I'd be delighted to see you cover in the near future or throw some help at..

I'm trying use a virtual machine as a web server. Now the only way I'v emanaged to get my VM's to connect to the internet is follow these directions (http://blogs.sqlxml.org/bryantlikes/archive/2008/01/09/setting-up-hyper-v-virtual-networking.aspx).

All well and good, but neither my router or other physical machines on my network know how to get to the 192.168.0.x stack.

How can I create a VM that is exposed and accessible to the internet (web server, remote desktop) and other machines in my physical network?

Saturday, January 12, 2008 6:40 PM by Mike Baz

# re: Understanding Networking with Hyper-V

There appears to be an odd bug wrt to networking in the current beta (it will be in Connect when I have the chance)... when creating a new VM you must have something, not sure what yet (TCP/IP?) bound to the real physical NIC for the new installation wizard to offer the card as a NIC for making a new network.  If you unbind everything it's not in the list... but afterwards, if you unbind and make a new network in the management console, you can do it.

Sunday, January 13, 2008 7:37 PM by BrentP

# Thanks Mike

That got it, was able to create the external network fine after unbinding.

Much appreciated!

Tuesday, January 15, 2008 9:42 AM by Daniel

# re: Understanding Networking with Hyper-V

I have the same 192 issue; what do you mean by unbind? In the VM's network setup or in the Hyper-V setup of the VM? Or in the host's Network setup? Or somewhere else?

Sunday, January 20, 2008 9:08 PM by BrentP

# re: Understanding Networking with Hyper-V

Daniel -

the unbinding is done on the host computer's physical network connection.

On the properties dialog for the network connection there's a section in the middle 'This connection uses the following items' (Client for Microsoft Networks, TCP/IP, etc).

In there you want to uncheck all the items and click OK.

If you now go back into the Hyper-V network settings on the host computer, you can create an external network bound to the network adapter WITHOUT getting the 'this adapater is already bound' error. Once it creates the new network adapter, change the settings of your virtual machine to use the new external adapter and go back into the propterties of your host computer and re-tick all the boxes as they were before.

You should then be good to go.

Wednesday, February 06, 2008 1:21 PM by Robert

# re: Understanding Networking with Hyper-V

Ugh. I'm sure there are good reason for this, but people experienced with VS2005 are going to be very very very very confused by this and probably assume it is an error!

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