Assume that you install the NEC PF1000 virtual switch extension on a Hyper-V server that is running Windows Server 2012. You try to send a packet to two network adapters by using the extension. In this situation, the Windows Server 2012 virtual network sends both packets by using the same network adapter instead of the two network adapters.
This issue occurs because the Windows Server 2012 virtual switch cannot identify the network adapter index number that is provided by the virtual switch extension.
Cumulative Update information
To resolve this issue, install the Windows 8 and Windows Server 2012 cumulative update 2811660. For more information about how to obtain this cumulative update package, click the following article number to view the article in the Microsoft Knowledge Base:
2811660 Windows 8 and Windows Server 2012 cumulative update: March 2013
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.
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