Configure Networking

Providing a virtual machine with networking capabilities requires the same two basic components that a physical computer requires: a network adapter and an available network. When you create a virtual machine, it is automatically configured with one network adapter. If one or more virtual networks are available on the server running Hyper-V, you can connect the network adapter to one of those networks at that time.

Hyper-V provides two types of virtual network adapters—a network adapter and a legacy network adapter:

A network adapter requires a virtual machine driver in order to work, but offers better performance. This driver is included with some newer versions of Windows. On all other supported operating systems, install integration services in the guest operating system to install the virtual machine driver. For instructions, see Install a Guest Operating System. For more information about which operating systems are supported and which of those require you to install integration services, see About Virtual Machines and Guest Operating Systems (http://go.microsoft.com/fwlink/?LinkID=128037).
A legacy network adapter works without installing a virtual machine driver. The legacy network adapter emulates a physical network adapter, multiport DEC 21140 10/100TX 100 MB. A legacy network adapter also supports network-based installations because it includes the ability to boot to the Pre-Execution Environment (PXE boot). However, the legacy network adapter is not supported in the 64-bit edition of Windows Server 2003.

	Note
	The legacy network adapter requires processing in the management operating system that is not required by the network adapter. We recommend that you use the legacy network adapter only to perform a network-based installation or when the guest operating system does not support the network adapter.

After you create a virtual machine, you can configure networking for virtual machines by adding, removing, and modifying their network adapters as necessary. Each network adapter can be connected to one of the virtual networks available on the server running Hyper-V.

	Note
	You can use Virtual Network Manager to add, remove, and modify virtual networks. You also can use Virtual Network Manager to specify a range of media access control (MAC) addresses to assign to virtual machines.

To add a network adapter

Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.
In the results pane, under Virtual Machines, select the virtual machine that you want to configure.
In the Action pane, under the virtual machine name, click Settings.
In the navigation pane, click Add Hardware.
On the Add Hardware page, choose a network adapter or a legacy network adapter. For more information about each type of adapter, see "Additional Considerations" below.
Click Add. The Network Adapter or Legacy Network Adapter page appears.
Under Network, select the virtual network you want to connect to.
If you want to configure a static MAC address or virtual LAN identifier, specify the numbers you want to use.
Click OK.

To modify or remove a network adapter

Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.
In the results pane, under Virtual Machines, select the virtual machine that you want to configure.
In the Action pane, under the virtual machine name, click Settings.
In the navigation pane, click the name of the network adapter.
On the Network Adapter or Legacy Network Adapter page, do one of the following:
- To modify the configuration, make your changes and then click Apply.
- To remove the network adapter, click Remove.
Click OK.

Additional considerations

By default, membership in the local Administrators group, or equivalent, is the minimum required to complete this procedure. However, an administrator can use Authorization Manager to modify the authorization policy so that a user or group of users can complete this procedure. For more information, see Using Authorization Manager for Hyper-V Security (http://go.microsoft.com/fwlink/?LinkId=142886).
You can use Virtual Network Manager to constrain the range of dynamic MAC addresses. When more than one physical computer running Hyper-V uses the same subnet, this helps you avoid potential conflicts that would result if the same MAC address is assigned to more than one virtual machine on the subnet.

Additional references

Manage Virtual Networks
For more information about Hyper-V, see Configuring Virtual Networks (http://go.microsoft.com/fwlink/?LinkID=131362).