Script: Creating an external virtual network with Hyper-V

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Moving on with the series, we arrive at creating an external virtual network.

VBScript:

 option explicit 

  

 Dim HyperVServer

 Dim SwitchFriendlyName

 Dim TypeLib

 Dim SwitchName

 Dim InternalEthernetPortFriendlyName

 Dim InternalSwitchPortFriendlyName

 Dim InternalSwitchPortName

 Dim InternalEthernetPortName

 Dim ExternalSwitchPortFriendlyName

 Dim ExternalSwitchPortName

 Dim ExternalEthernetPort

 Dim ExternalEthernetPorts

 Dim ExternalEthernetPortName

 Dim ExternalEthernetPortString

 Dim ScopeofResidence

 Dim WMIService 

 Dim VirtualSwitchManagementService

 Dim Switch

 Dim InternalSwitchPort

 Dim ExternalSwitchPort

 Dim InParam

 Dim OutParams

 Dim Job

 Dim Test

  

 'Prompt for the Hyper-V Server to use

 HyperVServer = InputBox("Specify the Hyper-V Server to create the internal virtual network switch:")

  

 'Get an instance of the WMI Service in the virtualization namespace.

 set WMIService = GetObject("winmgmts:\\" & HyperVServer & "\root\virtualization")

  

 'Get the Msvm_VirtualSwitchManagementService object

 set VirtualSwitchManagementService = WMIService.ExecQuery("select * from Msvm_VirtualSwitchManagementService").ItemIndex(0)

  

 'Get all possible physical network adapters that can be used for a switch

 Set ExternalEthernetPorts = WMIService.ExecQuery("Select * From Msvm_ExternalEthernetPort WHERE IsBound=False AND EnabledState=2")

  

 'Build the string to ask what physical network adapter to use

 ExternalEthernetPortString = "The following network adapters are available:" & chr(10) & chr(10)

  

 for each ExternalEthernetPort in ExternalEthernetPorts

    ExternalEthernetPortString = ExternalEthernetPortString & ExternalEthernetPort.Name & chr(10)

 next       

  

 ExternalEthernetPortString = ExternalEthernetPortString & chr(10) & "Please type in the (exact) name of the network adapter you want to use for the external connection:"

  

 'Setup a loop to keep on asking for a network adapter until we get a valid response

 Test = true

  

 while test

    ExternalEthernetPortName = InputBox(ExternalEthernetPortString)

    on error resume next

    Set ExternalEthernetPort = WMIService.ExecQuery("Select * From Msvm_ExternalEthernetPort WHERE Name='" & ExternalEthernetPortName & "' AND IsBound=False AND EnabledState=2").ItemIndex(0)       

    If Err.Number = 0 Then

       Test = false

    End If

    on error goto 0

 Wend

  

 'Get friendly name for the external virtual network switch (and the internal ethernet port)

 SwitchFriendlyName = InputBox("Specify the name of the new external virtual network switch:")

 InternalEthernetPortFriendlyName = SwitchFriendlyName 

  

 'Set the friendly name for the internal switch port and external switch port

 InternalSwitchPortFriendlyName = "InternalSwitchPort"

 ExternalSwitchPortFriendlyName = "ExternalSwitchPort"

  

 'Generate GUIDs for the unique switch name, internal switch port name, internal ethernet port name and external switch port name

 Set TypeLib = CreateObject("Scriptlet.TypeLib")

 SwitchName = TypeLib.Guid

  

 Set TypeLib = CreateObject("Scriptlet.TypeLib")

 InternalSwitchPortName = TypeLib.Guid

  

 Set TypeLib = CreateObject("Scriptlet.TypeLib")

 InternalEthernetPortName = TypeLib.Guid

  

 Set TypeLib = CreateObject("Scriptlet.TypeLib")

 ExternalSwitchPortName = TypeLib.Guid

  

 'Create a new virtual network switch

  

 'Setup the input parameter list

 set InParam = VirtualSwitchManagementService.Methods_("CreateSwitch").InParameters.SpawnInstance_()

 InParam.FriendlyName = SwitchFriendlyName

 InParam.Name = SwitchName 

 InParam.NumLearnableAddresses = 1024

 InParam.ScopeofResidence = null

  

 'Execute the method and store the results in OutParam

 set OutParams = VirtualSwitchManagementService.ExecMethod_("CreateSwitch", InParam)

  

 'Get the new switch object out of the results    

 Set Switch = WMIService.Get(OutParams.CreatedVirtualSwitch)

  

 'Create a new internal switch port

  

 'Setup the input parameter list

 set InParam = VirtualSwitchManagementService.Methods_("CreateSwitchPort").InParameters.SpawnInstance_()

 InParam.VirtualSwitch = Switch.Path_.Path

 InParam.FriendlyName = InternalSwitchPortFriendlyName

 InParam.Name = InternalSwitchPortName 

 InParam.ScopeofResidence = null

  

 'Execute the method and store the results in OutParam

 set OutParams = VirtualSwitchManagementService.ExecMethod_("CreateSwitchPort", InParam)

  

 'Get the new internal switch port out of the results    

 Set InternalSwitchPort = WMIService.Get(OutParams.CreatedSwitchPort)

  

 'Create a new external switch port

  

 'Setup the input parameter list

 set InParam = VirtualSwitchManagementService.Methods_("CreateSwitchPort").InParameters.SpawnInstance_()

 InParam.VirtualSwitch = Switch.Path_.Path

 InParam.FriendlyName = ExternalSwitchPortFriendlyName

 InParam.Name = ExternalSwitchPortName 

 InParam.ScopeofResidence = null

  

 'Execute the method and store the results in OutParam

 set OutParams = VirtualSwitchManagementService.ExecMethod_("CreateSwitchPort", InParam)

  

 'Get the new external switch port out of the results    

 Set ExternalSwitchPort = WMIService.Get(OutParams.CreatedSwitchPort)

  

 'Pull it all together with a call to SetupSwitch

  

 'Setup the input parameter list

 set InParam = VirtualSwitchManagementService.Methods_("SetupSwitch").InParameters.SpawnInstance_()

 InParam.ExternalSwitchPort = ExternalSwitchPort.Path_.Path

 InParam.InternalSwitchPort = InternalSwitchPort.Path_.Path

 InParam.ExternalEthernetPort = ExternalEthernetPort.Path_.Path

 InParam.InternalEthernetPortName = InternalEthernetPortName

 InParam.InternalEthernetPortFriendlyName = InternalEthernetPortFriendlyName

  

 'Execute the method and store the results in OutParams

 set OutParams = VirtualSwitchManagementService.ExecMethod_("SetupSwitch", InParam)

  

 'Check to see if the job completed synchronously

 if (OutParams.ReturnValue = 0) then

    Wscript.Echo "External virtual network created."

 elseif (OutParams.ReturnValue <> 4096) then

    Wscript.Echo "Failed to create external virtual network." & OutParams.ReturnValue

 else   

  

    'Get the job object

    set Job = WMIService.Get(OutParams.Job)

  

     'Wait for the job to complete (3 == starting, 4 == running)

    while (Job.JobState = 3) or (Job.JobState = 4)

       Wscript.Echo "Creating virtual network. " & Job.PercentComplete & "% complete"

       WScript.Sleep(1000)

  

       'Refresh the job object

       set Job = WMIService.Get(OutParams.Job)

    Wend

  

    'Provide details if the job fails (7 == complete)

    if (Job.JobState <> 7) then

       Wscript.Echo "External virtual network created."

       Wscript.Echo "ErrorCode:" & Job.ErrorCode

       Wscript.Echo "ErrorDescription:" & Job.ErrorDescription

    else

       Wscript.Echo "Failed to create external virtual network."

    end If

 end if

 

PowerShell:

 # Prompt for the Hyper-V Server to use

 $HyperVServer = Read-Host "Specify the Hyper-V Server to use (enter '.' for the local computer)"

  

 # List the available physical network adapters

 Write-Host "The following physical network adapters are avaiable for an external virtual network:"

  

 # Get the collection of external network adapters that are not associated with switches

 $query = "Select * From Msvm_ExternalEthernetPort WHERE IsBound=False AND EnabledState=2"

 $ExternalEthernetPorts = gwmi -namespace "root\virtualization" -Query $query -computername $HyperVServer

  

 # Output the elementname for each external nic

 foreach ($Nic in $ExternalEthernetPorts)       

    {          

       Write-Host $Nic.Name       

    } 

  

 # Keep on asking for a physical network adapter until we get a valid answer

 $ExternalEthernetPort = $null

  

 While ($ExternalEthernetPort -eq $null)

    {

    # Ask for the NIC name to use for the switch

    $ExternalEthernetPortName = Read-Host "Please type in the (exact) name of the network adapter you want to use for the external connection"

  

    # Get the WMI object for the external nic

    $query = "Select * From Msvm_ExternalEthernetPort WHERE Name='" + $ExternalEthernetPortName + "' AND IsBound=False AND EnabledState=2"

    $ExternalEthernetPort = gwmi -namespace "root\virtualization" -Query $query -computername $HyperVServer

    }

  

 # Get friendly name for the external virtual network switch (and internal ethernet port)

 $SwitchFriendlyName = Read-Host "Specify the name of the new external virtual network switch"

 $InternalEthernetPortFriendlyName = $SwitchFriendlyName

  

 # Set the friendly name for the internal switch port and external switch port

 $InternalSwitchPortFriendlyName = "InternalSwitchPort"

 $ExternalSwitchPortFriendlyName = "ExternalSwitchPort"

  

 # Generate GUIDs for the unique switch name, internal switch port name, internal ethernet port name and external switch port name

 $SwitchName = [guid]::NewGuid().ToString()

 $InternalSwitchPortName = [guid]::NewGuid().ToString()

 $InternalEthernetPortName = [guid]::NewGuid().ToString()

 $ExternalSwitchPortName = [guid]::NewGuid().ToString()

  

 # Setup some other values that will be used

 $NumLearnableAddresses = 1024

 $ScopeOfResidence = ""

  

 # Get the Msvm_VirtualSwitchManagementService WMI Object on the system we are going to be working with

 $VirtualSwitchManagementService = gwmi Msvm_VirtualSwitchManagementService -namespace "root\virtualization" -computername $HyperVServer

  

 # Create a new switch with 1024 learnable addresses

 $Result = $VirtualSwitchManagementService.CreateSwitch($SwitchName, $SwitchFriendlyName, $NumLearnableAddresses, $ScopeOfResidence) 

  

 # Get the WMI object for the new switch out of the results

 $Switch = [WMI]$Result.CreatedVirtualSwitch 

  

 # Create Internal Switch Port 

 $Result = $VirtualSwitchManagementService.CreateSwitchPort($Switch, $InternalSwitchPortName, $InternalSwitchPortFriendlyName, $ScopeOfResidence)

  

 # Get the WMI object for the new switch port out of the results

 $InternalSwitchPort = [WMI]$Result.CreatedSwitchPort 

  

 # Create External Switch Port 

 $Result = $VirtualSwitchManagementService.CreateSwitchPort($Switch, $ExternalSwitchPortName, $ExternalSwitchPortFriendlyName, $ScopeOfResidence)

  

 # Get the WMI object for the new switch port out of the results

 $ExternalSwitchPort = [WMI]$Result.CreatedSwitchPort 

  

 # Pull it all together with a call to SeutpSwitch

 $Result = $VirtualSwitchManagementService.SetupSwitch($ExternalSwitchPort, $InternalSwitchPort, $ExternalEthernetPort, $InternalEthernetPortName, $InternalEthernetPortFriendlyName)

  

 # Return success if the return value is "0"

 if ($Result.ReturnValue -eq 0)

    {write-host "External virtual network created."} 

  

 # If the return value is not "0" or "4096" then the operation failed

 ElseIf ($Result.ReturnValue -ne 4096)

    {write-host "Failed to create external virtual network."}

  

   Else

    {# Get the job object

     $job=[WMI]$Result.job

  

     # Provide updates if the jobstate is "3" (starting) or "4" (running)

     while ($job.JobState -eq 3 -or $job.JobState -eq 4)

       {write-host $job.PercentComplete

        start-sleep 1

  

        #Refresh the job object

        $job=[WMI]$Result.job}

  

      # A jobstate of "7" means success

     if ($job.JobState -eq 7)

        {write-host "External virtual network created."}

       Else

        {write-host "Failed to create external virtual network."

         write-host "ErrorCode:" $job.ErrorCode

         write-host "ErrorDescription" $job.ErrorDescription}

    }

Let’s step through the flow here:

  • First we iterate over all instances of Msvm_ExternalEthernetPort to let the user know what network adapters are available
  • Then we create a new virtual network (MSVM_VirtualSwitchManagementService.CreateSwitch)
  • Next we create an internal switch port and an external switch port (both using MSVM_VirtualSwitchManagementService.CreateSwitchPort)
    • This is making two jacks on the switch.  One to be connected to the physical network adapter and one to be connected to a virtual network adapter in the parent partition
  • Finally we hook everything together (MSVM_VirtualSwitchManagementService.SetupSwitch)
    • The SetupSwitch command not only connects the physical network adapter to the virtual network switch, but also creates a new virtual network adapter in the parent partition and copies the protocol configuration from the physical network adapter to the virtual network adapter

Some extra points to make:

  • When looking at physical network adapters (MSVM_ExternalEthernetPort):
    • Network adapters that are already connected to a virtual network will return “true” for “IsBound”
    • If you do not check the EnabledState you will see entries for old network adapters that are no longer present in the physical computer
    • You really should be using the “DeviceID” to uniquely identify network adapters, as the name is not guaranteed to be unique – but as no one knows the device ID, and the chances of a duplicate name are incredibly low – I prefer to use the name
  • Since I am asking the user to type in a long string for the network name – I have put in a loop so that if they make a mistake they have a chance to enter it again.
  • Most of the above methods return a result object that contains a reference to the WMI object that has been created.  You will see in the code that after each method call we then need to go and grab this object out of the results.
    • The results also contain a return code that indicates success or failure.  For brevity of code I am not checking this value and am assuming success on each of these calls – however for correctness you should be checking this value.
    • MSVM_VirtualSwitchManagementService.SetupSwitch is the one method that does not complete synchronously so you need to handle the job object for it.
  • The friendly name for the internal ethernet port is what appears as the device name for the virtual network adapter in the parent partition (when you open up the network connection management UI under Windows).  In these scripts I make it the same as the virtual network name – which is what the Hyper-V UI does – but you can make it anything you want.
  • For all the non-friendly names I am generating GUIDs.  This is not required but is strongly recommended.  These values are never displayed in the UI and are used for internal purposes and *must* be unique.
  • I have hardcoded the value for the friendly name of the internal switch port and external switch port.  I am doing this because the are never displayed in the UI and do not need to be unique.

Cheers,
Ben