Symptoms
Consider the following scenario:
-
You enable the TCP/IP Offloading feature on a computer that is running Windows 7 or Windows Server 2008 R2.
-
You have a TCP Offloading capable network adapter installed on the computer.
-
The network adapter does not support the Selective Acknowledgements (SACK) option.
In this scenario, the TCP SACK option is always set to "true" for offloaded TCP connections on the network adapter. This behavior causes poor performance in busy network environments.
Resolution
After you install this hotfix, the SACK option is automatically disabled if the following conditions are true:
-
The TCP Offloading feature is enabled.
-
You install a TCP offloading capable network adapter on the computer and keep it active.
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 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, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=supportNote 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 one of the following operating systems:
-
Windows 7
-
Windows 7 Service Pack 1 (SP1)
-
Windows Server 2008 R2
-
Windows Server 2008 R2 Service Pack 1 (SP1)
For more information about how to obtain a Windows 7 or a Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
976932 Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2
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
The global 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 7 and Windows Server 2008 R2 file information notes
Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" 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, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.
Version
Product
SR_Level
Service branch
6.1.760 0. 20xxx
Windows 7 and Windows Server 2008 R2
RTM
LDR
6.1.760 1. 21xxx
Windows 7 and Windows Server 2008 R2
SP1
LDR
-
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 Server 2008 R2 and for Windows 7" 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 x86-based versions of Windows 7
|
File name |
File version |
File size |
Date |
Time |
Platform |
|---|---|---|---|---|---|
|
Fwpkclnt.sys |
6.1.7600.20929 |
187,264 |
21-Mar-2011 |
04:44 |
x86 |
|
Tcpip.sys |
6.1.7600.20929 |
1,298,816 |
21-Mar-2011 |
04:44 |
x86 |
|
Fwpkclnt.sys |
6.1.7601.21687 |
187,776 |
19-Mar-2011 |
06:58 |
x86 |
|
Tcpip.sys |
6.1.7601.21687 |
1,300,864 |
19-Mar-2011 |
06:58 |
x86 |
For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
|
File name |
File version |
File size |
Date |
Time |
Platform |
|---|---|---|---|---|---|
|
Fwpkclnt.sys |
6.1.7600.20929 |
288,128 |
21-Mar-2011 |
05:35 |
x64 |
|
Tcpip.sys |
6.1.7600.20929 |
1,893,248 |
21-Mar-2011 |
05:36 |
x64 |
|
Fwpkclnt.sys |
6.1.7601.21687 |
288,640 |
19-Mar-2011 |
07:45 |
x64 |
|
Tcpip.sys |
6.1.7601.21687 |
1,927,552 |
19-Mar-2011 |
07:45 |
x64 |
For all supported IA-64-based versions of Windows Server 2008 R2
|
File name |
File version |
File size |
Date |
Time |
Platform |
|---|---|---|---|---|---|
|
Fwpkclnt.sys |
6.1.7600.20929 |
482,688 |
21-Mar-2011 |
04:11 |
IA-64 |
|
Tcpip.sys |
6.1.7600.20929 |
3,804,032 |
21-Mar-2011 |
04:12 |
IA-64 |
|
Fwpkclnt.sys |
6.1.7601.21687 |
483,200 |
19-Mar-2011 |
06:50 |
IA-64 |
|
Tcpip.sys |
6.1.7601.21687 |
3,807,616 |
19-Mar-2011 |
06:50 |
IA-64 |
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 updatesFor more information about Windows TCP features, click the following article number to view the article in the Microsoft Knowledge Base:
224829Description of Windows 2000 and Windows Server 2003 TCP Features For more information about TCP Selective Acknowledgment options, visit the following Microsoft website:
General information about TCP Selective Acknowledgment optionsFor more information about how to use TCP chimney offload, click the following Microsoft Developer Network (MSDN) website:
General information about how to use TCP Chimney Offload Note You cannot disable Selective Acknowledgements (SACK) in Windows 7 or in Windows Server 2008 R2 unless both of the following prerequisites are met:
-
You have a network adapter that can perform TCP chimney offloading.
-
You have installed the hotfix that is described in Microsoft Knowledge Base (KB) article 2525390.
Additionally, you cannot disable SACK by using the SackOpts registry key in Windows 7 or in Windows Server 2008 R2.
Additional file information
Additional file information for Windows 7 and for Windows Server 2008 R2
Additional files for all supported x86-based versions of Windows 7
|
File name |
Update.mum |
|
File version |
Not applicable |
|
File size |
2,773 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
X86_0512aa0464bfc19a711aba1be57414e3_31bf3856ad364e35_6.1.7601.21687_none_866f98539b510090.manifest |
|
File version |
Not applicable |
|
File size |
702 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
X86_1f2b73c4a0acdc952650bed1a1d7781b_31bf3856ad364e35_6.1.7600.20929_none_d817d3f48b37e5b1.manifest |
|
File version |
Not applicable |
|
File size |
702 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.20929_none_b3c2ef6ee0a325aa.manifest |
|
File version |
Not applicable |
|
File size |
3,834 |
|
Date (UTC) |
21-Mar-2011 |
|
Time (UTC) |
05:13 |
|
Platform |
Not applicable |
|
File name |
X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21687_none_b5666a72ddfc0967.manifest |
|
File version |
Not applicable |
|
File size |
3,834 |
|
Date (UTC) |
19-Mar-2011 |
|
Time (UTC) |
07:23 |
|
Platform |
Not applicable |
Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2
|
File name |
Amd64_51400f4928afb5a68a25eddbc206ab09_31bf3856ad364e35_6.1.7601.21687_none_9fa0325151e075f8.manifest |
|
File version |
Not applicable |
|
File size |
706 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
Amd64_e659707d62cacf300cb4f2a75472edda_31bf3856ad364e35_6.1.7600.20929_none_7711d76b14d02b43.manifest |
|
File version |
Not applicable |
|
File size |
706 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.20929_none_0fe18af2990096e0.manifest |
|
File version |
Not applicable |
|
File size |
3,838 |
|
Date (UTC) |
21-Mar-2011 |
|
Time (UTC) |
06:11 |
|
Platform |
Not applicable |
|
File name |
Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21687_none_118505f696597a9d.manifest |
|
File version |
Not applicable |
|
File size |
3,838 |
|
Date (UTC) |
19-Mar-2011 |
|
Time (UTC) |
08:17 |
|
Platform |
Not applicable |
|
File name |
Update.mum |
|
File version |
Not applicable |
|
File size |
3,215 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
Additional files for all supported IA-64-based versions of Windows Server 2008 R2
|
File name |
Ia64_68c1920b5e2460f5ecb8b4c8f4eca74a_31bf3856ad364e35_6.1.7600.20929_none_f1e5b4a54365fa8f.manifest |
|
File version |
Not applicable |
|
File size |
704 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
Ia64_856d75fc2dc29c51020ca7b136fbfd9f_31bf3856ad364e35_6.1.7601.21687_none_e94e75040f4aeed1.manifest |
|
File version |
Not applicable |
|
File size |
704 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
|
File name |
Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.20929_none_b3c49364e0a12ea6.manifest |
|
File version |
Not applicable |
|
File size |
3,836 |
|
Date (UTC) |
21-Mar-2011 |
|
Time (UTC) |
06:06 |
|
Platform |
Not applicable |
|
File name |
Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21687_none_b5680e68ddfa1263.manifest |
|
File version |
Not applicable |
|
File size |
3,836 |
|
Date (UTC) |
19-Mar-2011 |
|
Time (UTC) |
08:19 |
|
Platform |
Not applicable |
|
File name |
Update.mum |
|
File version |
Not applicable |
|
File size |
2,168 |
|
Date (UTC) |
22-Mar-2011 |
|
Time (UTC) |
02:07 |
|
Platform |
Not applicable |
