Knowledge Base

NT 4.0 Breaks SNA Server 2.x Server Communication Over IP

Article ID: 155883

Article Last Modified on 11/1/2006

APPLIES TO

Microsoft Windows NT Server 3.51

This article was previously published under Q155883

SYMPTOMS

After you upgrade from Windows NT 3.51 to Windows NT 4.0, SNA Server Admin is no longer able to locate the primary SNA Server 2.1/2.11 configuration server. This problem will occur if the SNA Server "server" computers are separated by TCP/IP routers and no LMHOSTS files are being used to define the Windows NT domain controllers where the SNA Servers are running.

When you start SNA Server Admin on a Backup SNA Server, the following error will be displayed:

The Primary SNA Server for the domain is not active.
OK to attempt to open to a Backup SNA Server in read only mode?

For more information on troubleshooting SNA Server 2.1 or 2.11 communication across TCP/IP routers, see the following Microsoft Knowledge Base article:

ARTICLE-ID: 148969
TITLE: Troubleshooting SNA Server Communication Over an IP Router

NOTE: Microsoft SNA Server 3.0 (to be released Fall 1996) does not rely on this Windows NT mechanism for server-to-server communication across TCP/IP routers. So, this issue is not relevant if SNA Server 3.0 is being used.

CAUSE

Optimizations made to Netbt.sys under Windows NT 4.0 have introduced a problem with SNA Server 2.x inter-server communication over TCP/IP routers.

RESOLUTION

Customers can work around the problem by adding an LMHOSTS file on the Windows NT 4.0 domain controllers where SNA Server is running and adding an entry for each SNA Server as follows:

   <ipaddress>   <computername>  #PRE #DOM:<winntdomainname>

For example:

   123.123.10.10   SNASERVER1  #PRE  #DOM:NTDOMAIN
   123.105.15.149  SNASERVER2  #PRE  #DOM:NTDOMAIN
   199.199.20.5    SNASALES    #PRE  #DOM:NTDOMAIN

An entry for each domain controller where SNA Server is running is required.

A Windows NT 4.0 fix to this problem is also available from Microsoft which does not require the above LMHOSTS entries (in other words, in WINS-only configurations).

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0. This problem was corrected in the latest Microsoft Windows NT 4.0 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

Keywords: kbbug kbnetwork KB155883

Microsoft KB Archive/155883

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