SQL Server logs 17832 with multiple TCP\IP connection requests

MORE INFORMATION

A Winsock application accepts connections on a port by calling a Listen() function, which has a backlog parameter specifying the maximum length of the pending-connection queue. The Winsock specification defines the maximum Listen() backlog at five and when it exceeds five, TCP/IP issues a Reset.

The backlog for SQL Server can be configured to handle a great number of pending connections by modifying the Windows NT Registry. In some cases, the connection reset issue is resolved due to the modification.

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

1. Start Registry Editor (REGEDT32.EXE) and locate the following Registry subkey in the HKEY_LOCAL_MACHINE subtree:

   \Software\Microsoft\MSSQLServer\MSSQLServer

   NOTES:
   • The corresponding registry subkey in the HKEY_LOCAL_MACHINE subtree for SQL 4.21a is:

     \Software\Microsoft\SQLServer\Server

   • If SQL Server 6.5 Enterprise Edition is running with a Virtual SQL Server in a clustered environment, you must make the change to virtual server key, rather than the standard:

     \Software\Microsoft\MSSQLServer\MSSQLServer

     This virtual server key is:

     \Software\Microsoft\MSSQLServer$VirtualServerName
     \MSSQLServer$VirtualServerName
     
     Value Name: WinsockListenBacklog
     Data Type: REG_DWORD
     Data: 190

   • The new registry location for SQL Server 2000 and for SQL Server 2005:
     
     For a default instance:

     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSSQLServer\MSSQLServer\SuperSocketNetLib

     For a named instance:

     HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\Instance Name\MSSQLServer\SuperSocketNetLib

2. Select the MSSQLServer subkey for SQL Server 6.5 and SQL Server 7.0, and select the SuperSocketNetLib for SQL Server 2000 and for SQL Server 2005. On the Edit menu, click Add Value.
3. Enter the following:

   Value Name: WinsockListenBacklog
   Data Type: REG_DWORD
   Data: Range is 1 to 0xFFFFFFFF

   NOTE: The data value affects overall system resources if it is set to a high value. Windows NT 3.51 has a maximum overall backlog of 100 and Windows NT 4.0 has a maximum overall backlog of 200 for all applications. The suggested method of testing with this value is to set the value in increments of five and observe the results until the connection reset stops.
4. Click OK and quit Registry Editor.
5. Restart SQL Server.

For more information about the Listen() function, see the WIN32 SDK Programmer's reference.

For more information about the backlog parameter and Windows NT, click the following article number to view the article in the Microsoft Knowledge Base: