Hyper-V: Reserve one or more external virtual networks for exclusive use by virtual machines

Applies To: Windows Server 2008 R2

This topic is intended to address a specific issue identified by a Best Practices Analyzer scan. You should apply the information in this topic only to computers that have had the Hyper-V Best Practices Analyzer run against them and are experiencing the issue addressed by this topic. For more information about best practices and scans, see Best Practices Analyzer.

Operating System

Windows Server 2008 R2








All external virtual networks are configured for use by both the management operating system and virtual machines.


Networking performance may be degraded in the management operating system.


Use Virtual Network Manager to stop sharing an external virtual network with the management operating system.

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).

To stop sharing the external virtual network with the management operating system

  1. Open Hyper-V Manager. Click Start, point to Administrative Tools, and then click Hyper-V Manager.

  2. From the Actions menu, click Virtual Network Manager.

  3. Under Virtual Networks, click the name of the external virtual network.

  4. In the Connection type area, under the name of the physical network adapter, clear the Allow the management operating system to share this network adapter check box.

  5. Click OK.