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Symptoms

Assume that you have a high-bandwidth, low-latency network environment on a computer that is running Windows 7 or Windows Server 2008 R2. In this situation, you notice that your data transfer speed is slower than expected.

Cause

This issue occurs because TCP window scaling does not work when network latency range is from 1 to 8 milliseconds.

Resolution

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 website:

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 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 apply 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.
    21xxx

    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

Fwpkclnt.sys

6.1.7600.21149

187,248

11-Feb-2012

05:40

Tcpip.sys

6.1.7600.21149

1,303,408

11-Feb-2012

05:40

Fwpkclnt.sys

6.1.7601.21921

187,760

11-Feb-2012

05:28

Tcpip.sys

6.1.7601.21921

1,306,480

11-Feb-2012

05:29

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

File name

File version

File size

Date

Time

Fwpkclnt.sys

6.1.7600.21149

288,112

11-Feb-2012

06:43

Tcpip.sys

6.1.7600.21149

1,879,920

11-Feb-2012

06:43

Fwpkclnt.sys

6.1.7601.21921

288,624

11-Feb-2012

06:27

Tcpip.sys

6.1.7601.21921

1,902,960

11-Feb-2012

06:27

For all supported IA-64–based versions of Windows Server 2008 R2

File name

File version

File size

Date

Time

Fwpkclnt.sys

6.1.7600.21149

482,672

11-Feb-2012

05:28

Tcpip.sys

6.1.7600.21149

3,808,112

11-Feb-2012

05:28

Fwpkclnt.sys

6.1.7601.21921

483,184

11-Feb-2012

05:22

Tcpip.sys

6.1.7601.21921

3,814,768

11-Feb-2012

05:22

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 updates

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

X86_7bc2f72213d974bff0b086036c6242de_31bf3856ad364e35_6.1.7600.21149_none_29d9525a2da453ea.manifest

File version

Not applicable

File size

702

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

X86_cf9315eaabbf3cd18982fad4adab4936_31bf3856ad364e35_6.1.7601.21921_none_0a26c38938071838.manifest

File version

Not applicable

File size

702

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21149_none_b3ad299ee0b38df5.manifest

File version

Not applicable

File size

3,834

Date (UTC)

11-Feb-2012

Time (UTC)

06:03

File name

X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21921_none_b5a14df0ddd0c12c.manifest

File version

Not applicable

File size

3,834

Date (UTC)

11-Feb-2012

Time (UTC)

05:55

Additional files for all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

File name

Amd64_9f738eeb2bb64069eacfa18a3c873938_31bf3856ad364e35_6.1.7600.21149_none_5956d5ff544c3faa.manifest

File version

Not applicable

File size

706

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

Amd64_f6335c15f18b28199be581d6a9df2baf_31bf3856ad364e35_6.1.7601.21921_none_ac93877a95f0a82f.manifest

File version

Not applicable

File size

706

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21149_none_0fcbc5229910ff2b.manifest

File version

Not applicable

File size

3,838

Date (UTC)

11-Feb-2012

Time (UTC)

07:06

File name

Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21921_none_11bfe974962e3262.manifest

File version

Not applicable

File size

3,838

Date (UTC)

11-Feb-2012

Time (UTC)

06:54

Additional files for all supported IA-64–based versions of Windows Server 2008 R2

File name

Ia64_e044d293ef2ba09977577b1edc9ddf8e_31bf3856ad364e35_6.1.7601.21921_none_c37dee8ee0c6daaa.manifest

File version

Not applicable

File size

704

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

Ia64_e89340469ef973098238c0c5961d8d82_31bf3856ad364e35_6.1.7600.21149_none_498ed1644367f8bb.manifest

File version

Not applicable

File size

704

Date (UTC)

11-Feb-2012

Time (UTC)

11:42

File name

Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21149_none_b3aecd94e0b196f1.manifest

File version

Not applicable

File size

3,836

Date (UTC)

11-Feb-2012

Time (UTC)

06:56

File name

Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21921_none_b5a2f1e6ddceca28.manifest

File version

Not applicable

File size

3,836

Date (UTC)

11-Feb-2012

Time (UTC)

06:46

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