Telnet Connection Seems Slow

ID: Q214432

The information in this article applies to:
IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SYMPTOMS

When you use the Telnet tool, the connection may seem slow.


CAUSE

This behavior can occur if you connect to a Telnet server that does not comply with Request for Comment (RFC) 2018.


RESOLUTION

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).
To work around this behavior, disable the TCP Selective Acknowledgement Options (SACK) feature using Registry Editor.

Enter a data value of zero (0) for the SackOpts value in the following registry key:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP

Note that you may have to create the SackOpts value. If you have to create the SackOpts value, create it as a string value.

For more information, see page 625 of the Microsoft Windows 98 Resource Kit.


STATUS

This behavior is by design.


MORE INFORMATION

Windows 98 includes support for TCP Selective Acknowledgement Options, as described in RFC 2018, in the Microsoft Transmission Control Protocol/Internet Protocol (TCP/IP). The updated Microsoft TCP/IP provides better performance when it is used in various network topologies and Winsock programs.

The slow performance develops when a remote host attempts to establish a connection with a server that does not comply with RFC 2018. When the remote host attempts to negotiate using the additional TCP Selective Acknowledgement information, the server responds with a smaller TCP/IP packet size. The final result is a very small TCP/IP packet size of 8 bytes that significantly reduces the data flow.

The Microsoft Windows Sockets 2.0 update also includes support for TCP Selective Acknowledgement Options. However, due to implementation differences, it does not display the same behavior. For more information about the Windows Sockets 2.0 update, see the following article in the Microsoft Knowledge Base: Availability of Windows Sockets 2.0 for Windows 95

Additional query words: crawl 


Keywords          : kbtool win98 
Version           : WINDOWS:
Platform          : WINDOWS 
Issue type        : kbprb

Last Reviewed: January 21, 1999