Multicast packets are dropped in Windows 7 or in Windows Server 2008 R2

Symptoms

Assume that an application connects to several multicast groups and receives data from those groups on a computer that is running Windows 7 or Windows Server 2008 R2. In this situation, packets are dropped between the network adapter and the application.

Notes

  • This issue occurs when multiple sockets are bound to the same User Datagram Protocol (UDP) port.

  • The performance of the computer may be affected when this issue occurs.

Cause

The number of multicast subscriptions does not cause this issue.

This issue occurs because of the way that Windows handles and delivers incoming multicast traffic to endpoints.

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 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 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.
    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

6.1.7600.21083

187,248

02-Nov-2011

21:13

Tcpip.sys

6.1.7600.21083

1,302,384

02-Nov-2011

21:13

Fwpkclnt.sys

6.1.7601.21853

187,760

02-Nov-2011

22:53

Tcpip.sys

6.1.7601.21853

1,303,920

02-Nov-2011

22:54

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

6.1.7600.21083

288,112

02-Nov-2011

22:02

Tcpip.sys

6.1.7600.21083

1,878,896

02-Nov-2011

22:02

Fwpkclnt.sys

6.1.7601.21853

288,624

03-Nov-2011

00:36

Tcpip.sys

6.1.7601.21853

1,905,008

03-Nov-2011

00:37

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

File name

File version

File size

Date

Time

Fwpkclnt.sys

6.1.7600.21083

482,672

02-Nov-2011

21:17

Tcpip.sys

6.1.7600.21083

3,798,384

02-Nov-2011

21:17

Fwpkclnt.sys

6.1.7601.21853

483,184

02-Nov-2011

20:59

Tcpip.sys

6.1.7601.21853

3,801,456

02-Nov-2011

21:00

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_a104379b6bbd75ea62f43fdfaa745a3d_31bf3856ad364e35_6.1.7601.21853_none_2d7c4f83a38a757b.manifest

File version

Not applicable

File size

702

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

X86_d92a016650ecbf53dc64c53fef3ec42b_31bf3856ad364e35_6.1.7600.21083_none_1e1de3ffc2f5ee39.manifest

File version

Not applicable

File size

702

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21083_none_b37be64ce0d96888.manifest

File version

Not applicable

File size

3,834

Date (UTC)

02-Nov-2011

Time (UTC)

21:36

File name

X86_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21853_none_b582dcdadde74a86.manifest

File version

Not applicable

File size

3,834

Date (UTC)

02-Nov-2011

Time (UTC)

23:25

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

File name

Amd64_0f4bf103bc319500d758bcdba10f3fe1_31bf3856ad364e35_6.1.7601.21853_none_56da1aa231abf86a.manifest

File version

Not applicable

File size

706

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

Amd64_b9931ea00d7996caf7e0883547583e2e_31bf3856ad364e35_6.1.7600.21083_none_b9cabf4498e5e4ff.manifest

File version

Not applicable

File size

706

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21083_none_0f9a81d09936d9be.manifest

File version

Not applicable

File size

3,838

Date (UTC)

02-Nov-2011

Time (UTC)

22:32

File name

Amd64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21853_none_11a1785e9644bbbc.manifest

File version

Not applicable

File size

3,838

Date (UTC)

03-Nov-2011

Time (UTC)

01:24

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

File name

Ia64_46daf5d30632c79465ae38d52f90e90a_31bf3856ad364e35_6.1.7600.21083_none_43d2538119b13e47.manifest

File version

Not applicable

File size

704

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

Ia64_fcb32c38810aaf05ce0217e5c7b736a0_31bf3856ad364e35_6.1.7601.21853_none_2b0901174b0f53da.manifest

File version

Not applicable

File size

704

Date (UTC)

03-Nov-2011

Time (UTC)

17:02

File name

Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7600.21083_none_b37d8a42e0d77184.manifest

File version

Not applicable

File size

3,836

Date (UTC)

02-Nov-2011

Time (UTC)

22:34

File name

Ia64_microsoft-windows-tcpip-binaries_31bf3856ad364e35_6.1.7601.21853_none_b58480d0dde55382.manifest

File version

Not applicable

File size

3,836

Date (UTC)

02-Nov-2011

Time (UTC)

23:57

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