NETBIOS Defaults To 16 Sessions on Windows NT

• Microsoft Windows NT Workstation versions 3.51 and 4.0
• Microsoft Windows NT Server versions 3.51 and 4.0

SYMPTOMS

On your computer running Windows NT, after your NETDDE application connects to 16 nodes a NetDDE error is reported periodically to the event log and a 17th connection to another node is prohibited.

In Windows NT, the default maximum number of sessions (connections) that a NetDDE application program can request is 16. For NetDDE applications, each NetBIOS session is a connection to another node. Therefore, the maximum number of nodes that a DDE server can connect with NetBIOS is currently limited to 16 nodes.

CAUSE

In the NetDDE NetBIOS dynamic link library (NDDENB32.DLL), the NetBIOS reset command is currently set to the default value of 16 for the maximum number of sessions.

RESOLUTION

Install the fix referenced below (under STATUS) and modify the registry as follows:

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

1. Run the Registry Editor(REGEDT32.EXE).

2. Under the HKEY_LOCAL_MACHINE subtree, go to the following subkey:

         Software\Microsoft\NetDDE\Parameters\NetBIOS
   

3. If the value is not defined in the right window pane, choose Add Value from the Edit menu.

4. Type or select the following information when prompted with the field names on the left:

       Value Name: MaxSessions
        Date Type   : REG_DWORD
        Data              : <number of maximum sessions>
   
      where <number of maximum sessions> is a value from 0 to 254. If it is
      set to zero, it defaults to 16 sessions maximum.
   
   

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51 and 4.0. This problem was corrected in the latest Windows NT U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

   S E R V P A C K