Windows NT RAS Server Doesn't Forward Datagrams

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1

SYMPTOMS

Windows NT applications fail when attempting to communicate through RAS, although they can communicate through NetBEUI if they are on the same network. Attempts to send a datagram back to the workstation from the Windows NT application also fail.

A protocol analyzer sees no RAS traffic from the remote machine to the network.

CAUSE

The failure occurs when a program sends datagrams with a NetBIOS name as the destination, but with the Permanent Name (Ethernet card address) of the sending workstation as the source. RAS servers do not accept Permanent Name IDs because RAS workstations are not guaranteed to have unique IDs, as are workstations with network adapter cards.

RESOLUTION

Change the application to send datagrams that use a NetBIOS name as the source. The application routine submitting the datagram must use a NetBIOS name registered by the application, and should copy the name into the Source Name field of the network control block before calling NetBIOS.

NetBIOS chat programs--which communicate with datagrams, using unique NetBIOS names created by the applications--operate successfully through RAS. The Net send 'domain' command is a good example. When delivering to a domain, it uses a datagram mechanism.

CONFIGURATION

The problem was been observed on this configuration:

   Windows NT Advanced Server 3.1 (528:CSD002) RAS server
   Windows NT 3.1 (528:CSD002), WFWG 3.11 or LM 2.2; Win3.1 Clients