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Q193684: APPC/CPI-C Apps May Hang When Allocating LU 6.2 Sessions

Article: Q193684
Product(s): Microsoft SNA Server
Version(s): 3.0 SP2,3.0 SP3,4.0,4.0 SP1
Operating System(s): 
Keyword(s): kbbuglist
Last Modified: 24-OCT-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1 
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SYMPTOMS
========

An APPC or CPI-C application may occasionally fail to establish a session after
a host system (Mainframe or AS/400) initiates the Change Number of Sessions
(CNOS) negotiation.

Applications may exhibit different symptoms if this occurs, depending on how the
application is written. If the application has timeout, the application will
terminate the session after the timeout has been reached. Applications that do
not have a timeout may appear to hang (stop responding) while waiting for the
Allocate call to complete.

This problem did not occur with SNA Server 3.0 SP1 and earlier.

CAUSE
=====

This problem can occur when the host system initiates CNOS negotiation with the
SNA Server. When this occurs, suspended LU 6.2 sessions are in an unusable state
by SNA Server, causing application-generated Open LU 6.2 Requests (for example,
ALLOCATEs) to hang.

CNOS negotiation is not commonly initiated by the host system. SNA Server usually
initiates CNOS negotiation because of application requests for LU 6.2 sessions,
or because the SNA Server is configured to auto activate LU 6.2 sessions.
Therefore, occurrences of this problem are not common.

This problem was exposed due to a change included in SNA Server 3.0 SP2 to
correct the problem described in the following Knowledge Base article:

  Q170070 SNA Client Allocate Requests May Hang After AS/400 IPL

RESOLUTION
==========

SNA Server 3.0
--------------

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

  Q184307 How to Obtain the Latest SNA Server Version 3.0 Service Pack



SNA Server 4.0
--------------

Microsoft has confirmed this to be a problem in SNA Server version 4.0 and 4.0
SP1. This problem was corrected in the latest SNA Server version 4.0 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


STATUS
======

Microsoft has confirmed this to be a problem in SNA Server versions 3.0 SP2, 3.0
SP3, 4.0, and 4.0 SP1. This problem was first corrected in SNA Server 3.0
Service Pack 4.

Additional query words:

======================================================================
Keywords          :  kbbuglist
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400 kbSNAServ300SP3 kbSNAServ400SP1 kbSNAServ300SP2
Version           : :3.0 SP2,3.0 SP3,4.0,4.0 SP1
Issue type        : kbbug
Solution Type     : kbfix

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