Fast Retransmissions Are Triggered Incorrectly When You Enable Selective Acknowledgments (SACKS)

This article has been archived. It is offered "as is" and will no longer be updated.
When you transfer data by means of a Transmission Control Protocol (TCP) connection with the Selective Acknowledgment feature (SACK) enabled, you might see unnecessary fast retransmissions if a packet is lost.
This problem may occur if SACK block updates that are sent by the receiving end are incorrectly interpreted as duplicate acknowledgements and they then trigger fast retransmissions.

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 this specific problem.

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, submit a request to 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: 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.


No prerequisites are required.

Restart Requirement

You must restart your computer after you apply this hotfix.

Hotfix Replacement Information

This hotfix does not replace any other hotfixes.

File Information

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
   Date         Time   Version        Size     File name   --------------------------------------------------------   21-Sep-2003  00:41  5.0.2195.6824  118,960  Afd.sys   09-Oct-2003  17:38  5.0.2195.6824  105,232  Msafd.dll   09-Oct-2003  02:17  5.0.2195.6864  318,480  Tcpip.sys   21-Sep-2003  00:41  5.0.2195.6824   16,240  Tdi.sys   09-Oct-2003  17:38  5.0.2195.6824   17,680  Wshtcpip.dll
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.
More information
For additional information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:
816915 New Naming Schema for Microsoft Windows Hotfix Packages
For additional information, 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
ack retransmit error duplicate traffic bidirectional transmit tcp ip selective acknowledgements

Article ID: 830392 - Last Review: 10/26/2013 10:31:00 - Revision: 3.0

Microsoft Windows 2000 Server, Microsoft Windows 2000 Advanced Server

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