Microsoft KB Archive/258978

= Type of Service Field Cannot Be Set in Windows 2000 =

Article ID: 258978

Article Last Modified on 10/31/2006

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APPLIES TO


 * Microsoft Interix 2.2 Standard Edition

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This article was previously published under Q258978



IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SUMMARY
The Winsock call to set IP Type of Service (IPTOS) options on a socket generates an error on Microsoft Windows 2000-based computers. This is because of the industry standard Quality of Service (QoS) feature that is being implemented industry wide for the allocation of bandwidth to on-demand programs, such as video and audio types of programs. A program can no longer set Type of Service (ToS) as this could be a violation of policy, and as of the implementation of TCP/IP for Windows 2000, the six bits that made up the vastly unused ToS field have been renamed and given a new function under QoS. They are now called DiffServ. Microsoft has added a registry value which, when set, tells Winsock to fail attempts to set TOS.



MORE INFORMATION
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

In Interix, this causes an error message to be generated. This behavior can be corrected by editing the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\TcpIp\Parameters\DisableUserTOSSetting

This value defaults to 1 (to turn on the disabling) for Windows 2000.

Keywords: kbinfo KB258978

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