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Q140840: 2 Connections Using Same Link Service and Destination Address

Article: Q140840
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11
Operating System(s): 
Keyword(s): 
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, on platform(s):
   - the operating system: Microsoft Windows NT 
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SYMPTOMS
========

When SNA Server has two connections configured to use the same underlying link
service and same Remote Network Address, the remote end deactivates the first
connection as soon as an XID packet to activate the second connection arrives.

It is true that two link stations cannot use the same source service access point
(SAP) address to the same destination link station. However, SNA Server should
not disrupt an already active connection when another request arrives for the
same Network address (or SAP) for the same link service.

With SNA Server 2.11 the following message appears when attempting to configure
two connections in this way:

  The same Remote Network Address and SAP have already been specified for this
  link service in connection <connection name>. To create more than one
  connection to the same remote machine, add one of more 802.2/DLC link
  services via SNA Server Setup over the same adapter with different local SAP
  addresses. This will auto-create additional connections in SNA Server Admin.
  Alternatively, if further SAPs are available at the remote machine, choose a
  different remote SAP for this connection. OK.

After you choose OK, SNA Server does not force the Administrator to change the
the configuration. Therefore, the above problem results.

RESOLUTION
==========

Microsoft has a fix that does not prevent an Administrator from configuring two
connections for the same remote network address using the same link service. The
808.2 Link Service now detects the address conflict and disables the second
connection with the following event id:

  Event ID: 205 - "An address pair is already in use."

Note that it also detects the case where the address pair is first "in use" due
to an incoming call as well as an outbound one.

Microsoft has updated the following files to correct this problem:

  <snaroot>\SYSTEM\SNASERVR.EXE
  <snaroot>\SYSTEM\TRCSERVR.EXE
  <snaroot>\SYSTEM\SNADLC.DLL
  <snaroot>\SYSTEM\SNAEVENT.DLL

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This
problem was corrected in the latest SNA Server for Windows NT, 2.11 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

Additional query words: prodsna 2.00 2.10 2.11 snatrace

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Keywords          :  
Technology        : kbAudDeveloper kbSNAServSearch
Version           : WINDOWS:2.0,2.1,2.11
Issue type        : kbbug
Solution Type     : kbfix

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