You see this error message because the switch protocol is already enabled on that NIC.  It’s enabled either because there is already a virtual network using that adapter or because something or someone enabled it incorrectly.  If you already have a virtual network using that NIC, you can’t use that NIC on two virtual networks.

 If you ever need to completely remove all virtual networks from your system, you could use one of the options below (I recommend extreme caution ):

Delete all your virtual networks.

I wouldn’t recommend running it remotely because it will tear down your network stack but it should restore it once completed.

/*
Copyright (c) Microsoft Corporation
 
Module Name:
 
    nvspscrub.js
 
*/

//
// VirtualSwitchManagementService object.  Logical wrapper class for Switch Management Service
//
function
VirtualSwitchManagementService(
    Server,
    User,
    Password
    )
{
    //
    // Define instance fields.
    //   
    this.m_VirtualizationNamespace  = null;
   
    this.m_VirtualSwitchManagementService = null;
       

    //
    // Instance methods
    //       
   
    VirtualSwitchManagementService.prototype.DeleteSwitch =
    function(
        VirtualSwitch
        )
       
    /*++

    Description:

        Deletes a virtual switch
       
    Arguments:

        VirtualSwitch – Msvm_VirtualSwitch object to delete

    Return Value:

        SWbemMethod.OutParameters object.

    –*/
   
    {
        var methodName = "DeleteSwitch";

        var inParams = this.m_VirtualSwitchManagementService.Methods_(methodName).inParameters.SpawnInstance_();

        inParams.VirtualSwitch = VirtualSwitch.Path_.Path;
       
        return this.m_VirtualSwitchManagementService.ExecMethod_(methodName, inParams);
    }
   
   
    VirtualSwitchManagementService.prototype.DeleteInternalEthernetPort =
    function(
        InternalEthernetPort
        )

    /*++

    Description:

        Deletes an internal ethernet port
       
    Arguments:

        InternalEthernetPort – Msvm_InternalEthernetPort to delete
       
    Return Value:

        SWbemMethod.OutParameters object.

    –*/

    {
        var methodName = "DeleteInternalEthernetPort";

        var inParams = this.m_VirtualSwitchManagementService.Methods_(methodName).inParameters.SpawnInstance_();
       
        inParams.InternalEthernetPort = InternalEthernetPort.Path_.Path;
       
        return this.m_VirtualSwitchManagementService.ExecMethod_(methodName, inParams);
    }
   
    VirtualSwitchManagementService.prototype.UnbindExternalEthernetPort =
    function(
        ExternalEthernetPort
        )

    /*++

    Description:

        Unbinds an external ethernet port from the virtual network subsystem.  Usually this method
         won’t be called directly
       
    Arguments:

        SwitchPort – Msvm_ExternalEthernetPort to unbind.

    Return Value:

        SWbemMethod.OutParameters object.

    –*/

    {
        var methodName = "UnbindExternalEthernetPort";

        var inParams = this.m_VirtualSwitchManagementService.Methods_(methodName).inParameters.SpawnInstance_();

        inParams.ExternalEthernetPort = ExternalEthernetPort.Path_.Path;
       
        return this.m_VirtualSwitchManagementService.ExecMethod_(methodName, inParams);
    }
   
    //
    // Utility functions
    //
   
    VirtualSwitchManagementService.prototype.WaitForNetworkJob =
    function(
        OutParams
        )

    /*++

    Description:

        WMI calls will exit with some type of return result.  Some will require
        a little more processing before they are complete. This handles those
        states after a wmi call.

    Arguments:

        OutParams – the parameters returned by the wmi call.

    Return Value:

        Status code

    –*/

    {
        if (OutParams.ReturnValue == 4096)
        {
            var jobStateStarting        = 3;
            var jobStateRunning         = 4;
            var jobStateCompleted       = 7;
   
            var networkJob;

            do
            {
                WScript.Sleep(1000);
               
                networkJob = this.m_VirtualizationNamespace.Get(OutParams.Job);

            } while ((networkJob.JobState == jobStateStarting) ||
                     (networkJob.JobState == jobStateRunning));

            if (networkJob.JobState != jobStateCompleted)
            {
                throw(new Error(networkJob.ErrorCode,
                                networkJob.Description + " failed: " + networkJob.ErrorDescription));
            }
           
            return networkJob.ErrorCode;
        }

        return OutParams.ReturnValue;
    }
   
    VirtualSwitchManagementService.prototype.GetSingleObject =
    function(
        SWbemObjectSet
        )

    /*++

    Description:

        Takes a SWbemObjectSet which is expected to have one object and returns the object

    Arguments:

        SWbemObjectSet – The set.

    Return Value:

        The lone member of the set.  Exception thrown if Count does not equal 1.

    –*/

    {
        if (SWbemObjectSet.Count != 1)
        {
            throw(new Error(5, "SWbemObjectSet was expected to have one item but actually had " + SWbemObjectSet.Count));
        }
       
        return SWbemObjectSet.ItemIndex(0);
    }

   
    //
    // Aggregate functions
    //
    VirtualSwitchManagementService.prototype.DeleteSwitchAndWait =
    function(
        VirtualSwitch
        )
       
    /*++

    Description:

        Deletes a switch
       
    Arguments:

        VirtualSwitch – Msvm_VirtualSwitch to delete
       
    Return Value:
   
        None.

    –*/
   
    {
        var outParams = this.DeleteSwitch(VirtualSwitch);

        var wmiRetValue = this.WaitForNetworkJob(outParams);

        if (wmiRetValue != 0)
        {
            throw(new Error(wmiRetValue, "DeleteSwitch failed"));
        }
    }
   
    VirtualSwitchManagementService.prototype.DeleteInternalEthernetPortAndWait =
    function(
        InternalEthernetPort
        )
    /*++

    Description:

        Deletes an internal ethernet port
       
    Arguments:

        InternalEthernetPort – Msvm_InternalEthernetPort to delete
       
    Return Value:

        SWbemMethod.OutParameters object.

    –*/
   
    {
        var outParams = this.DeleteInternalEthernetPort(InternalEthernetPort);

        var wmiRetValue = this.WaitForNetworkJob(outParams);

        if (wmiRetValue != 0)
        {
            throw(new Error(wmiRetValue, "DeleteInternalEthernetPortAndWait failed"));
        }
    }
   
   
    VirtualSwitchManagementService.prototype.UnbindExternalEthernetPortAndWait =
    function(
        ExternalEthernetPort
        )
    /*++

    Description:

        unbinds an internal ethernet port
       
    Arguments:

        ExternalEthernetPort – Msvm_ExternalEthernetPort to unbind
       
    Return Value:

        SWbemMethod.OutParameters object.

    –*/
   
    {
        var outParams = this.UnbindExternalEthernetPort(ExternalEthernetPort);

        var wmiRetValue = this.WaitForNetworkJob(outParams);

        if (wmiRetValue != 0)
        {
            throw(new Error(wmiRetValue, "UnbindExternalEthernetPortAndWait failed"));
        }
    }
   
    //
    // Constructor code
    //
   
    if (Server == null)
    {
        Server = WScript.CreateObject("WScript.Network").ComputerName;
    }
   
    //
    // Set Namespace fields
    //
    try
    {
        var locator = new ActiveXObject("WbemScripting.SWbemLocator");

        this.m_VirtualizationNamespace = locator.ConnectServer(Server, "root\virtualization", User, Password);
    }
    catch (e)
    {
        this.m_VirtualizationNamespace = null;
       
        throw(new Error("Unable to get an instance of Virtualization namespace: " + e.description));
    }
   
    //
    // Set Msvm_VirtualSwitchManagementService field
    //
    try
    {
        var physicalComputerSystem =
                this.m_VirtualizationNamespace.Get(
                        "Msvm_ComputerSystem.CreationClassName=’Msvm_ComputerSystem’,Name=’" + Server + "’");
         
        this.m_VirtualSwitchManagementService = this.GetSingleObject(
                                                        physicalComputerSystem.Associators_(
                                                            "Msvm_HostedService",
                                                            "Msvm_VirtualSwitchManagementService",
                                                            "Dependent"));
    }
    catch (e)
    {
        this.m_VirtualSwitchManagementService = null;
       
        throw(new Error("Unable to get an instance of Msvm_VirtualSwitchManagementService: " + e.description));
    }
}

//
// main
//

var wshShell = WScript.CreateObject("WScript.Shell");

var g_NvspWmi   = null;

Main();

function Main()
{
 WScript.Echo("Looking for nvspwmi…");
 g_NvspWmi   = new VirtualSwitchManagementService();

 WScript.Echo("");
 WScript.Echo("Looking for internal (host) virtual nics…");
 var list = g_NvspWmi.m_VirtualizationNamespace.ExecQuery("SELECT * FROM Msvm_InternalEthernetPort");
 for (i = 0; i < list.Count; i++)
 {
  var next = list.ItemIndex(i);
  WScript.echo(next.DeviceID);
  g_NvspWmi.DeleteInternalEthernetPortAndWait(next);
 }
 
 WScript.Echo("");
 WScript.Echo("Looking for switches…");
 list = g_NvspWmi.m_VirtualizationNamespace.ExecQuery("SELECT * FROM Msvm_VirtualSwitch");
 for (i = 0; i < list.Count; i++)
 {
  var next = list.ItemIndex(i);
  WScript.echo(next.Name);
  g_NvspWmi.DeleteSwitchAndWait(next);
 }
 
 WScript.Echo("");
 WScript.Echo("Looking for external nics…");
 list = g_NvspWmi.m_VirtualizationNamespace.ExecQuery("SELECT * FROM Msvm_ExternalEthernetPort WHERE IsBound=TRUE");
 for (i = 0; i < list.Count; i++)
 {
  var next = list.ItemIndex(i);
  WScript.echo(next.DeviceID);
  g_NvspWmi.UnbindExternalEthernetPortAndWait(next);
 }
 
 WScript.Echo("");
 WScript.Echo("Finished!");
}

Hyper-V Server 2008 R2 Live Migration and High Availability can be managed in a few different ways:

1. Failover Cluster Manager/Hyper-V Manager from a Windows Server 2008 R2 Server OR,
2. System Center Virtual Machine Manager 2008 R2 OR,

.using the FREELY (there’s that word again) available Failover Cluster Manager/Hyper-V Manager for Windows 7. So, as you can see, there are a few different options depending on your needs and option three give you Live Migration and High Availability at zero cost.

BTW: If you decide to go with option #2 System Center Virtual Machine Manager 2008 R2, you certainly can do a lot more such as:

• Heterogeneous Virtualization Management
• Rich PowerShell Support for Datacenter Automation
• Maintenance mode
• Virtual Machine Library Support
• Templates, Clones, Sysprep Integration
• Performance Resource Optimization (PRO)

.and a lot, lot more. But, I digress.

$$$ Comparison

Let’s take a look at a few cluster configurations and compare costs for Live Migration and High Availability functionality.

You may be wondering, "Did he choose the most expensive VMware configuration?" On the contrary, I chose the least expensive configuration ($2245 per processor) that offers both Live Migration and High Availability.

You may be wondering, "Why isn’t System Center management represented here?"

In this example, I simply wanted to compare the lowest cost for Live Migration and High Availability functionality from Microsoft and VMware with some real world configurations that a small/medium business may use. I will post a follow-up blog that adds management for small/medium businesses. As for enterprise customers, they typically have larger server farms with more sophisticated management requirements. That’s another blog for another time.

You may also be wondering, "Why isn’t the cost of guest operating systems included here?"

Simple, neither Microsoft Hyper-V Server 2008 R2 nor VMware include any guest operating system licenses so if you need to run 4 copies of Windows Server, you need to purchase the appropriate license. That cost is the same whether you’re running Hyper-V Server 2008 R2 or VMware so I didn’t bother to include it.

While VMware claims to be more affordable the facts are clear and the value of Microsoft Hyper-V Server 2008 R2 is undeniable. Microsoft offers exceptional value especially for small and mid-market customers who have told us for years how they would like Live Migration/High Availability functionality and simply can’t afford it.

Those days are over.

At this point you may be thinking we’re crazy to provide virtualization live migration and high availability at no cost. Well, I wish we could say we were first, but the folks at Xen have been providing free Live Migration and HA for a few months. In fact, the only one still charging for Live Migration and High Availability ($2245+ per socket) is VMware.

Now that’s crazy.

Published on http://blogs.technet.com/virtualworld/default.aspx by Jeff Woolsey, Principal Group Program Manager, Windows Server, Hyper-V