Microsoft KB Archive/830392

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

Article ID: 830392

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server

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SYMPTOMS
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.



CAUSE
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 now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
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



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; 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

Additional query words: ack retransmit error duplicate traffic bidirectional transmit tcp ip selective acknowledgements

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe kbwin2000presp5fix KB830392

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