The Soul of a Virtual Machine : Virtual Networking

Connecting virtual machines to separate physical networks

megand — Sat, 08 Jan 2005 01:12:00 GMT

You can attach each virtual machine running under the same instance of Virtual Server to a separate physical network and also isolate the virtual machine network traffic from the host, as follows:

On the network adapters (NICs) to which you will attach your virtual machines, unbind all services except the Virtual Machine Network Service. Instructions are below.
On the NIC that you will use for the host, unbind the Virtual Machine Network Service.
Connect each NIC to a separate physical network.
Connect each NIC (except the one used by the host) to a separate virtual network.
Connect each virtual machine to the appropriate virtual network.
In the guest operating systems, configure the network settings, such as IP address, submask, gateway, DNS, etc.

To bind or unbind the Virtual Machine Network Service from a NIC:

On the host computer, click "Start," click "Control Panel," and then click "Network Connections."
Right-click the connection that uses the NIC you want to configure and click "Properties."
On the "General" tab, select or clear the check box for the service to bind or unbind, and then click "OK."

Note: You can isolate virtual machine network traffic from the host at any time by unbinding Virtual Machine Network Services from the NIC used by the host. For more information about network isolation, see "Virtual network architecture" in the Virtual Server 2005 Administrator's Guide.

For general information about configuring networks for virtual machines, see "Accessing virtual networks from a virtual machine" and "Creating a virtual network" in the Virtual Server 2005 Administrator's Guide.

Fixing network connectivity issues with Broadcom NICs

megand — Wed, 29 Dec 2004 01:14:00 GMT

Virtual Server sometimes takes issue with Broadcom NICs. If you're experiencing any connectivity problems, and you're using a Broadcom NIC, turn off the Offload TCP Segmentation, Checksum Offload, and Large Send Offload settings for the NIC, as follows (all of these settings may not be available):

In the Network Connections control panel, right-click the connection and click "Properties."
Click "Configure."
In the Property list on the Advanced tab, select "Offload TCP Segmentation."
In the Value box, select "Off."
In the Property list, select "Checksum Offload."
In the Value box, select "Off."
In the Property list, select "Large Send Offload."
In the Value box, select "Off," and then click "OK."

The computer will restart.

Note: When you change network adapter properties, the virtual machines attached to that adapter may loose their network connections. To restore the network connections, you must disconnect the affected virtual machines from the virtual network adapter that is attached to that physical network adapter and then reconnect them to it, as follows:

From the Virtual Server Administration Website, shut down or turn off the virtual machine.
On the virtual machine configuration page, click "Network adapters."
In the "Connected to" box, select "Not connected," and then click "OK."
In the "Connected to" box, select the virtual network adapter, and then click "OK."

If this doesn't restore connectivity, then you'll need to restart the host computer.

Sandboxing a virtual machine under Virtual PC

megand — Thu, 02 Dec 2004 19:46:00 GMT

Michael asked the following question about sandboxing a virtual machine. I thought it might be of general interest, so decided to post the answer, which Ben Armstrong, our resident Virtual PC guru has provided (http://blogs.msdn.com/Virtual_PC_Guy).

Question: I'd like to use a virtual machine as a sandbox which permits the user to do "ugly" things in IE without damaging the host OS. Therefore, it is my interest to block any means of communication between host and guest, including drag and drop, network access, etc.
1. Do you consider Virtual PC appropriate for this?
2. How can I disable drag and drop?
3. How can I disable guest access to the host without limiting Internet access?

Answer (thanks Ben!): Yes – Virtual PC 2004 would be appropriate for this. To disable the integration features under a Windows 2000 or Windows XP virtual machine, you just need to disable the ‘Virtual Machine Additions Services Application’ and ‘Virtual Machine Additions Shared Folder Service’ services in the guest OS. To disable host access – but leave Internet access in place – use Shared Networking.

Virtual Server doesn't recognize a host network adapter

megand — Tue, 23 Nov 2004 22:51:00 GMT

When you add a network adapter to the host computer (including a Loopback adapter) the new adapter won't appear as an option on the Network Properties page for any virtual network, so you won't be able to connect a virtual network to it. To fix this problem, you need to enable the Virtual Machine Network Services driver on the adapter, as follows:

On the host computer, click "Start," click "Control Panel," and then click "Network Connections."
Right-click the connection that uses the new network adapter and click "Properties."
On the "General" tab, select the "Virtual Machine Network Services" check box, and then click "OK."

The network adapter should now appear in the "Network adapter on physical computer" list on the Network Properties page of any virtual network.

You can follow this procedure any time Virtual Server doesn’t recognize a network adapter. This is a rare occurance, but if there's already a virtual network configured on this network adapter, you'll have to remove from the virtual network any virtual machines that are using it and then re-connect them. Otherwise the virtual machines won’t have network connectivity. You do this as follows:

Open the Virtual Server Administration Website.
In the left pane under "Virtual Machines," point to "Configure" and click the virtual machine.
In the lower part of the page, click "Network adapters."
Click "Remove" and then click "OK."
In the lower part of the page, click "Network adapters," and click "Add Network Adapter."
In the "Connected to" box, select the network adapter to use, and then click "OK."