BUG: RPC NetBIOS Calls Fail over RAS

- Microsoft Windows NT Workstation version 3.51 - Microsoft Windows NT Server version 3.51

SYMPTOMS

When RPC calls attempt to register a NetBIOS protocol sequence as an endpoint with Remote Access Services (RAS) installed, you may receive error messages such as error 1704 "The RPC protocol sequence is invalid" or error 1720 "The endpoint cannot be created."

CAUSE

The problem occurs because RAS incorrectly enters some information in the registry when installed.

RESOLUTION

Taking the RPC-related RAS entries out of the registry resolves this issue.

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

1. Start the Registry Editor.

2. Select the HKEY_LOCAL_MACHINE subtree.

3. Go to the SOFTWARE\Microsoft\RPC\NetBIOS key.

4. To the right you will see the protocol sequences that can be registered by an RPC application. For a machine with a single network card and RAS, you may see:

   ncacn_nb_tcp0 ncacn_nb_nb0 ncacn_nb_ipx0 ncacn_nb_tcp1 ncacn_nb_nb1 ncacn_nb_ipx1

   These values will have a dword that signifies the binding order. If the network adapter driver was installed prior to RAS (most likely), remove all the sequences that end in 1. The sequences are written to the registry in the order the device driver was installed, so you must know the order in which network cards and RAS were installed. Once the RAS bound protocol sequences are removed, the RPC calls will always go over the RAS link when a call is made.

STATUS

Microsoft has confirmed this to be a problem in Windows NT version 3.51. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.