Virtual switch extension cannot send packets separately through every individual network adapter in Windows Server 2012


Consider the following scenario:
  • You have a virtual switch extension installed on a Windows Server 2012-based Hyper-V server.
  • The extension sends packets that contain one or more of the following flags: 



In this scenario, the packets are sent by using the same network adapter in the virtual network.


This issue occurs because Network Driver Interface Specification (NDIS) chains the Net Buffer Lists (NBLs) incorrectly.


Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


To apply this hotfix, you must be running Windows Server 2012.

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.
File information


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

Additional file information

Additional file information for Windows Server 2012

Additional files for all supported x64-based versions of Windows Server 2012
File nameAmd64_microsoft-windows-ndis-minwin_31bf3856ad364e35_6.2.9200.16549_none_b24f6a87b1ab4af1.manifest
File versionNot applicable
File size246,273
Date (UTC)05-Mar-2013
Time (UTC)08:12
PlatformNot applicable
File nameAmd64_microsoft-windows-ndis-minwin_31bf3856ad364e35_6.2.9200.20653_none_b2c835aacad66ea2.manifest
File versionNot applicable
File size246,273
Date (UTC)05-Mar-2013
Time (UTC)07:39
PlatformNot applicable

Article ID: 2823958 - Last Review: Apr 9, 2013 - Revision: 1

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