Windows 95 and Windows 98 TCP/IP May Retransmit Packets Prematurely

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

This problem occurs because TCP uses a retransmit timer to retransmit packets that do not seem 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 Windows 95 and Windows 98 TCP/IP stack incorrectly computes the retransmit timer because of a math error. When you transmit packets over high-delay networks, this can result in unnecessary retransmissions and lower throughput.

Windows 98 and Windows 98 Second Edition

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem immediately, download the fix by clicking the download link later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site: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.

The following file is available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The English-language version of this fix should have the following file attributes or later:

Windows 95 and Windows 95 OSR 1, 2, 2.1, 2.5

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem.

To resolve this problem immediately, download the fix by clicking the download link later in this article or contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site: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.

The following file is available for download from the Microsoft Download Center:
For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base: Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file. The English-language version of this fix should have the following file attributes or later:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed at the beginning of this article.

You can observe the TCP retransmission count by using the netstat -s command.

For additional information about this issue as it pertains to Microsoft Windows NT, click the article number below to view the article in the Microsoft Knowledge Base: For additional information about Windows 95 hotfixes, click the article number below to view the article in the Microsoft Knowledge Base: For additional information about Windows 98 and Windows 98 Second Edition hotfixes, click the article number below to view the article in the Microsoft Knowledge Base: