Virtual machine network fails when you start the second VM on a Windows Server 2012 R2-based Hyper-V server

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 EssentialsWindows Server 2012 R2 Foundation

Symptoms


Consider the following scenario:

  • You have two child virtual machines (VMs) configured by using the same virtual network adapter in a Windows Server 2012 R2-based Hyper-V environment.
  • You install a third-party virtual switch extension in the same environment.
  • You configure a VLAN ID (enable VLAN tagging) on the virtual switch.
  • You apply the minimumbandwidthweight port profile setting to the VM network by using the Hyper-V virtual machines, the System Center Virtual Machine Manager (SCVMM) high bandwidth adapter or the medium bandwidth adapter, native port profile.
  • You try to start both of the VMs.
In this scenario, network communication from the VMs fails. For example, a ping command fails with a "destination host unreachable" error.

Cause


This issue occurs because the virtual switch does not preserve the VLAN tag when the packets are sent in this configuration. Therefore, they never reach the destination VLAN.

Resolution


To resolve this issue, install update rollup 2962409. For more information about how to obtain this update rollup package, click the following article number to view the article in the Microsoft Knowledge Base:

2962409  Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 update rollup: June 2014

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information


For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates