Symptoms
When you have a virtual machine that has the Large Send Offload (LSO) feature of Hyper-V Network Virtualization enabled, network communication is very slow.
Cause
This problem occurs because of an issue in the LSO feature of Hyper-V Network Virtualization. The Push bit is not being propagated correctly, and this causes the push timer to be invoked.
Resolution
Hotfix information
A supported hotfix is available from Microsoft Support. 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 the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
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, contact 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, go to the following Microsoft website:
http://support.microsoft.com/contactus/?ws=support 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.
Prerequisites
To apply this hotfix, you must be running Windows 8.1 or Windows Server 2012 R2.
Additionally, you must first install update 2919355 on Windows 8.1 or Windows Server 2012 R2.
Restart requirement
You must restart the computer after you apply this hotfix.
Hotfix replacement information
This hotfix does not replace any previously released hotfix.
File information
The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows 8.1 and Windows Server 2012 R2 file information and notesImportant Windows 8.1 and Windows Server 2012 R2 hotfixes are included in the same packages. However, only "Windows 8.1" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 8.1" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
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.
Version Product Milestone Service branch 6.3.960 0.16 xxx Windows 8.1 and Windows Server 2012 R2 RTM GDR 6.3.960 0.17 xxx Windows 8.1 and Windows Server 2012 R2 RTM DR The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 8.1 and Windows Server 2012 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely 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.
For all supported x64-based versions of Windows 8.1 and Windows Server 2012 R2
| File name | File version | File size | Date | Time | Platform |
|---|---|---|---|---|---|
| Wnv.sys | 6.3.9600.17084 | 706,048 | 28-Mar-2014 | 06:28 | x64 |
| Vmsntfy.dll | 6.3.9600.16384 | 88,576 | 22-Aug-2013 | 10:49 | x64 |
Additional file information
Additional file information for Windows 8.1 and Windows Server 2012 R2
Additional files for all supported x64-based versions of Windows 8.1 and Windows Server 2012 R2
| File name | Amd64_1066018ab12bb8e1d11653f3cd1d98dc_31bf3856ad364e35_6.3.9600.17084_none_463fb732d6f2dc74.manifest |
|---|---|
| File version | Not applicable |
| File size | 708 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_2e910e18c9787499ca85e346060f53f8_31bf3856ad364e35_6.3.9600.17084_none_0016ea03766d9463.manifest |
| File version | Not applicable |
| File size | 701 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_692b627d3aa6079eb47d150e4d59248e_31bf3856ad364e35_6.3.9600.17084_none_ffc48e9508e9511e.manifest |
| File version | Not applicable |
| File size | 725 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_dde236bfd7d00860b87bac9599cfe49e_31bf3856ad364e35_6.3.9600.17084_none_c7d38a52dd5a3ab5.manifest |
| File version | Not applicable |
| File size | 695 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_microsoft-hyper-v-d..ch-coresystem-state_31bf3856ad364e35_6.3.9600.17084_none_e85405a2439043e0.manifest |
| File version | Not applicable |
| File size | 10,075 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_microsoft-hyper-v-drivers-vmswitch_31bf3856ad364e35_6.3.9600.17084_none_59c97d1454141111.manifest |
| File version | Not applicable |
| File size | 7,637 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_microsoft-windows-ndis-lbfo_31bf3856ad364e35_6.3.9600.17084_none_02224435eac7fe98.manifest |
| File version | Not applicable |
| File size | 21,660 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_microsoft-windows-wnv_31bf3856ad364e35_6.3.9600.17084_none_a0645a2f2abb5681.manifest |
| File version | Not applicable |
| File size | 54,090 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_wvms_pp.inf_31bf3856ad364e35_6.3.9600.17084_none_53a3d6eec5598a05.manifest |
| File version | Not applicable |
| File size | 3,379 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Amd64_wvms_pp_coresys.inf_31bf3856ad364e35_6.3.9600.17084_none_6221ea3160489a34.manifest |
| File version | Not applicable |
| File size | 3,411 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_1_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 2,304 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_2_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 1,908 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_3_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 2,004 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_4_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 1,873 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_5_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 1,847 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_6_for_kb2956241~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 2,074 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_for_kb2956241_rtm_gm~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 2,806 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
| File name | Package_for_kb2956241_rtm~31bf3856ad364e35~amd64~~6.3.1.0.mum |
| File version | Not applicable |
| File size | 3,471 |
| Date (UTC) | 30-Mar-2014 |
| Time (UTC) | 01:33 |
| Platform | Not applicable |
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.