Network is corrupted between Guest OS and external network for VMs hosted on Windows 8.1 or Windows Server 2012 R2

This article describes an issue in which the network traffic is corrupted between Guest OS and the external network for virtual machines (VMs) that are hosted on Windows 8.1 or Windows Server 2012 R2. A hotfix is available to fix this issue. Before you install this hotfix, see the Prerequisites section.
Symptoms
This issue occurs when you route traffic from a VM network adapter to another VM or host network adapter, and when Large Send Offload (LSO) v2 is enabled on the VM network adapter.
Cause
This issue occurs because the VM switch may not set LSO information correctly when outgoing packets are forwarded between VM and host network adapters.

Hotfix information

Important If you install a language pack after you install this hotfix, you must reinstall this hotfix. Therefore, we recommend that you install any language packs that you need before you install this hotfix. For more information, see Add language packs to Windows.

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

If the hotfix is available for download, there's a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section doesn't appear, submit a request to Microsoft Customer Service and Support to get 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 don't 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 don't see your language, it's because a hotfix isn't available for that language.

Prerequisites

To apply this hotfix, install update 2919355 in Windows 8.1 or Windows Server 2012 R2.

Registry information

To use the hotfix in this package, you don't have to make any changes to the registry.

Restart requirement

You may have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix doesn't replace a previously released hotfix.
File Information
The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). Be aware that dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time bias. The dates and times may also change when you perform certain operations on the files.

Windows 8.1 and Windows Server 2012 R2

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.3.960 0.17 xxxWindows 8.1 and Windows Server 2012 R2RTMGDR
    6.3.960 0.18 xxxWindows 8.1 and Windows Server 2012 R2RTMGDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
x64 Windows 8.1 and Windows Server 2012 R2
File nameFile versionFile sizeDateTimePlatform
Vmsif.dll6.3.9600.1739665,02408-Oct-201405:53x64
Vmsnetsetupplugin.dll6.3.9600.1739633,79208-Oct-201406:07x64
Vmswitch.sys6.3.9600.18086689,15208-Oct-201517:33x64
Vmsif.dll6.3.9600.1739665,02408-Oct-201405:53x64
Vmsntfy.dll6.3.9600.1739691,64808-Oct-201406:54x64
Vmswitch.sys6.3.9600.18086689,15208-Oct-201517:33x64
Vmsif.dll6.3.9600.1739665,02408-Oct-201405:53x64
Vmsntfy.dll6.3.9600.1739691,64808-Oct-201406:54x64
Vmswitch.sys6.3.9600.18086689,15208-Oct-201517:33x64
Vmsif.dll6.3.9600.1739665,02408-Oct-201405:53x64
Vmsntfy.dll6.3.9600.1739691,64808-Oct-201406:54x64
Vmswitch.sys6.3.9600.18086689,15208-Oct-201517:33x64

Additional file information

x64 Windows 8.1 and Windows Server 2012 R2
File propertyValue
File nameAmd64_0140230e6202200b304391ecea98411a_31bf3856ad364e35_6.3.9600.18086_none_b2b7e84f9ca1bf41.manifest
File versionNot applicable
File size725
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameAmd64_4a257e5b81b15fc83d9132c5e0ea7dd6_31bf3856ad364e35_6.3.9600.18086_none_41877c9067678c6b.manifest
File versionNot applicable
File size708
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameAmd64_microsoft-hyper-v-d..ch-coresystem-state_31bf3856ad364e35_6.3.9600.18086_none_e855ef6e438e902f.manifest
File versionNot applicable
File size10,027
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameAmd64_microsoft-hyper-v-drivers-vmswitch_31bf3856ad364e35_6.3.9600.18086_none_59cb66e054125d60.manifest
File versionNot applicable
File size7,613
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameAmd64_wvms_pp.inf_31bf3856ad364e35_6.3.9600.18086_none_53a5c0bac557d654.manifest
File versionNot applicable
File size3,379
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameAmd64_wvms_pp_coresys.inf_31bf3856ad364e35_6.3.9600.18086_none_6223d3fd6046e683.manifest
File versionNot applicable
File size3,411
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size2,737
Date (UTC)09-Oct-2015
Time (UTC)12:49
PlatformNot applicable
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
See the terminology that Microsoft uses to describe software updates.
Properties

Article ID: 3092604 - Last Review: 11/11/2015 00:28:00 - Revision: 1.0

Windows Server 2012 R2 Datacenter, Windows Server 2012 R2 Standard, Windows Server 2012 R2 Essentials, Windows Server 2012 R2 Foundation, Windows 8.1 Enterprise, Windows 8.1 Pro, Windows 8.1

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