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

ID: Q236926

The information in this article applies to:

Microsoft Windows 95
Microsoft Windows 95 OEM Service Release versions 1, 2, 2.1, 2.5
Microsoft Windows 98
Microsoft Windows 98 Second Edition

SYMPTOMS

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 retransmitted may be unnecessarily high.

CAUSE

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 are transmitting packets over high-delay networks, this can result in unnecessary retransmissions and lower throughput.

RESOLUTION

Windows 98 and Windows 98 Second Edition

The following file is available for download from the Microsoft Download Center. Click the file name below to download the file:

236926up.exe

The 236926up.exe file contains the following files:


   Date        Time      Version     Size     File name
   ----------------------------------------------------
   08/13/99    2:04pm    4.10.2223   60,281   Vtcp.386

For more information about how to download files from the Microsoft Download Center, please visit the Download Center at the following Web address

http://www.microsoft.com/downloads/search.asp

and then click How to use the Microsoft Download Center.

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

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the fix. 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://www.microsoft.com/support/supportnet/overview/overview.asp

The English language version of this fix should have the following file attributes or later:


   Date       Time       Version     Size     File name   Platform
   ---------------------------------------------------------------------
   07/29/99   12:53pm    4.00.1658   60,245   Vtcp.386    Windows 95
                                                          + WinSock2

STATUS

Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

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, please see the following article in the Microsoft Knowledge Base:

Q232512 TCP/IP may Retransmit Packets Prematurely

Additional query words:

Keywords : kbnetwork osr1 osr2 win95 win98 win98se
Version : WINDOWS:95
Platform : WINDOWS
Issue type : kbprb