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Q161775: Problem Starting Two Non-Queued TPs Simultaneously on Win3.x

Article: Q161775
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.1,2.11
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.1, 2.11 
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SYMPTOMS
========

If the host allocates two conversations at the same time, causing two instances
of a non-queued autostarted TP to be invoked on an SNA Server Windows 3.x
client, the following sequence of events occurs:

1. Two instances of the program are started.

2. The first program issues a RECEIVE_ALLOCATE that completes after 20 or more
  seconds, and normal data flow occurs.

3. The second program issues a RECEIVE_ALLOCATE that fails with the following
  error:

  primary_rc = 0x0002 (AP_STATE_CHECK)
  secondary_rc = 0x00000509 (AP_ALLOCATE_NOT_PENDING)

  When this occurs, the first program stops responding.

4. The computer running SNA Server may report the following events in the
  Windows NT Application event viewer:

  Event 60
  Failed to invoke APPC TP <value>, sense data = X'084C0000'
  AP_TRANS_PGM_NOT_AVAIL_NO_RETRY.

  Event 557
  DLOAD has timed out.

  Event 575
  Failed to Execute a program, RC=8 name=<value>.

If there is a 30-second delay between host attach requests, the problem doesn't
occur; both APPC TP's are invoked, and they run fine.

CAUSE
=====

This is a problem in the SNA Server 2.11 Windows 3.x client. If the Windows 3.x
client receives two dynamic load requests from two different servers within five
seconds, the SNA client (Wdmod.dll) may send the second acknowledgement
(RCV_ALLOC) message to the wrong server.

STATUS
======

Microsoft has confirmed this to be a problem in SNA Server version 2.1 and 2.11.
This problem was corrected in the latest SNA Server version 2.11 U.S. Service
Pack. For information on obtaining this service pack, query on the following
word in the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K


A supported fix is now available, but has not been fully regression- tested and
should be applied only to systems experiencing this specific problem. Unless you
are severely impacted by this specific problem, Microsoft recommends that you
wait for the next Service Pack that contains this fix. Contact Microsoft
Technical Support for more information.



Additional query words: prodsna

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Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ211 kbSNAServ210
Version           : WINDOWS:2.1,2.11

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