PRB: Connect to SQL on NT 3.5 from WFW 3.11 via Named Pipes

ID: Q121258

The information in this article applies to:

SYMPTOMS

A Microsoft Windows for Workgroups version 3.11 client (WFW 3.11) is designed to connect to SQL Server on Microsoft Windows NT version 3.5 via named pipes over the IPX/SPX-Compatible transport (NWLink). However, an enhancement in Windows NT 3.5 and WFW 3.11 called "direct hosting" can prevent existing WFW 3.11 clients from reliably connecting using named pipes over NWLink. Direct hosting is a feature that allows the virtual redirector on the client side and the network server on the server side to interface directly to the underlying NWLink transport, bypassing NetBIOS, which provides faster performance.

This problem may happen following an upgrade of the operating system on which SQL Server runs from Windows NT 3.1 to version 3.5. The typical symptom of this problem is that WFW 3.11 SQL Server clients are unable to connect to SQL Server on Windows NT 3.5 using named pipes over NWLink.

The errors received by the DB-Library (DB-Lib) clients are:

Network error on drive ?
Possible network error, read from SQL server failed.

The error received by ODBC clients is: 

   [Microsoft][ODBC SQL Server Driver]TDS buffer length too large(#0)


WORKAROUND

Currently, there are two solutions to this connection problem. However, due to the improved performance introduced in the first solution below, it is strongly recommended that you use the first solution.

Solution 1. Updating WFW 3.11 Files:

There are 6 updated WFW 3.11 system files that include a new version of the Windows for Workgroups redirector and other network support files that provide improved performance. These files are distributed on the Windows NT Server version 3.5 CD, in the \CLIENTS\WFW\UPDATE directory.

The updated files are: 

   NDIS.386
   NET.EXE
   NETAPI.DLL
   NWNBLINK.386
   VNETSUP.386
   VREDIR.386

These files should be used only for Windows for Workgroups version 3.11. They will allow named pipe connections to work properly to Microsoft SQL Server over direct host IPX.

To install these new files on a computer running Windows for Workgroups 3.11:
  1. Copy all the files from the \CLIENTS\WFW\UPDATE directory on the Windows NT Server CD into the local C:\WINDOWS\SYSTEM directory of the Windows for Workgroups 3.11-based client.

    Note: Remember to use the Windows NT Server CD. The Microsoft SQL Server CD does not contain these files.


  2. On the Windows for Workgroups 3.11-based client, move the NET.EXE file from C:\WINDOWS\SYSTEM to C:\WINDOWS.


  3. Reboot the WFW 3.11 workstation.


Solution 2. Modifying the SYSTEM.INI Setting:

If, for whatever reasons, you prefer not to apply the updated WFW 3.11 files as described above, you can avoid the named pipes connection problem by updating the SYSTEM.INI file on the WFW 3.11 clients.

Using any text editor, you can edit the SYSTEM.INI file to set DirectHost=off in [network] section: 

   [network]
   DirectHost=off

You need to reboot your client workstation after the modification.

NOTE: Although either solution should work, the first solution is preferred because these files provide a general maintenance upgrade along with a number of fixes and improvements.

Additional query words: Direct Host Windows NT dblib 


Keywords          : kbinterop SSrvWinNT 
Version           : 4.2
Platform          : WINDOWS 
Issue type        :

Last Reviewed: March 20, 1999