DOCUMENT:Q153665  08-AUG-2001  [winnt]
TITLE   :SPX Data Stream Type Header May Reset Unexpectedly
PRODUCT :Microsoft Windows NT
PROD/VER:winnt:3.51,4.0
OPER/SYS:
KEYWORDS:kbnetwork

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The information in this article applies to:

 - Microsoft Windows NT Workstation versions 3.51, 4.0 
 - Microsoft Windows NT Server versions 3.51, 4.0 
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SYMPTOMS
========

The SPX Data Stream Type (DS_TYPE) portion of the SPX packet header may reset
unexpectedly in socket applications that use the DS_TYPE socket option.

CAUSE
=====

When the DS_TYPE option is set, SPX sets a global flag that is specific to that
connection indicating what the new DS_TYPE value should be on Sends. Because the
global flag can be reset before Sends queued in SPX are transmitted on the
network, the potential exists for the DS_TYPE to be changed before pending Sends
have been transmitted.

In the following example, the application is intended to complete five Sends with
DS_TYPE set to 1:

Example:

1. Application sets the SPX DS_TYPE to 1

2. Application indicates five Sends that are queued in SPX.

3. SPX completes four of the Sends on the network using DS_TYPE 1.

4. Application sets the SPX DS_TYPE to 0.

5. SPX completes the remaining Send on the network using DS_TYPE 0.

The example above fails because the DS_TYPE has been changed before the final
queued Send has completed.

RESOLUTION
==========

Obtain the fix mentioned below. SPX has been modified to submit the DS_TYPE with
every request instead of setting DS_TYPE before the actual Send.

STATUS
======

Microsoft has confirmed this to be a problem in Windows NT version 3.51 and 4.0.
This problem was corrected in the latest Windows NT 3.51 U.S. Service Pack and
in the latest 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


Additional query words: prodnt 3.51 4.00

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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT400search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS351search
Version           : winnt:3.51,4.0
Issue type        : kbbug

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