TCP/IP May Retransmit Packets Prematurely

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Article ID: 232512 - View products that this article applies to.
This article was previously published under Q232512
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SYMPTOMS

When transmitting data over high-delay networks (for example, satellite links), transfer throughput may be lower than expected and the number of packets retransmitted may be unnecessarily high.

CAUSE

This problem occurs because TCP uses a retransmit timer to retransmit packets that do not appear to have reached the receiver. To set this timer, TCP uses information about the historical Round Trip Time (RTT) for each connection, which it measures by observing the time between sending packets and receiving acknowledgments for them.

The Microsoft Windows NT 4.0 TCP/IP stack incorrectly computes the retransmit timer because of a math error. When transmitting packets over high-delay networks, this can result in unnecessary retransmissions and lower throughput.

RESOLUTION

Windows NT Server or Workstation 4.0

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to:
  • 152734 how to obtain the latest windows nt 4.0 service pack
For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:
http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

Windows NT Server 4.0, Terminal Server Edition

To resolve this problem, obtain the latest service pack for Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack

STATUS

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT Server version 4.0, Terminal Server Edition Service Pack 6.

MORE INFORMATION

The TCP retransmission count can be observed using the Performance Monitor utility or using the "netstat -s" command.

For additional information about this issue as it pertains to Microsoft Windows 95/98, please see the following article in the Microsoft Knowledge Base:
236926 Windows 95/98 TCP/IP May Retransmit Packets Prematurely

Properties

Article ID: 232512 - Last Review: June 6, 2012 - Revision: 3.0
APPLIES TO
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
Keywords: 
kbhotfixserver kbqfe kbbug kbfix KB232512

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