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Q245487: APPC Program Never Retries New Local LU From Pool

Article: Q245487
Product(s): Microsoft SNA Server
Version(s): 4.0,4.0 SP1,4.0 SP2,4.0 SP3
Operating System(s): 
Keyword(s): kbDSupport kbsna kbSNA400sp4fix kbSNA400PreSP4fix
Last Modified: 13-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3 
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SYMPTOMS
========

If an APPC application supplies a blank Local APPC LU alias to TP_STARTED and
calls [MC_]ALLOCATE multiple times using rtn_ctl = AP_WHEN_SESSION_FREE (where
all sessions on a Local APPC LU become in use), [MC_]ALLOCATE requests may start
to fail even though other Local APPC LUs from the default pool are available.

CAUSE
=====

If an APPC application calls TP_STARTED once and receives a default Local APPC
LU, all subsequent conversations that use that tp_id will use the same Local
APPC LU alias. The APPC DLL (WAPPC32.dll) was not written to try a different
default Local APPC LU in this case.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for SNA Server 4.0. For
additional information, please see the following article in the Microsoft
Knowledge Base:

  Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack



WORKAROUND
==========

An APPC application may work around this problem by calling TP_STARTED before
every [MC_]ALLOCATE request (and by calling TP_ENDED after each conversation is
not allocated).

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft SNA Server version
4.0, 4.0 SP1, 4.0 SP2 and 4.0 SP3.

This problem was first corrected in SNA Server 4.0 Service Pack 4.

MORE INFORMATION
================

This specific problem won't occur with a CPIC application since CPIC doesn't
support the equivalent of the APPC "AP_WHEN_SESSION_FREE" return control
setting.


Additional query words:

======================================================================
Keywords          : kbDSupport kbsna kbSNA400sp4fix kbSNA400PreSP4fix 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400 kbSNAServ400SP1 kbSNAServ400SP2 kbSNAServ400SP3
Version           : :4.0,4.0 SP1,4.0 SP2,4.0 SP3
Issue type        : kbbug
Solution Type     : kbfix

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