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Q160991: SNA Server Sends Sense Code 400D to Host after CD Received

Article: Q160991
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.11,2.11 SP1,3.0
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 2.11, 2.11 SP1, 3.0 
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SUMMARY
=======

When SNA Server receives an SNA message from the host with the Change-Direction
(CD) bit set on a full duplex LU0 session, SNA Server will reject the message
with sense code 400D:

  Event 21: Negative Response Sent on Connection <value> (SENSE=400D)

  where 400D = CD Not Supported: The Change-Direction indicator was set,
  but is not supported

SNA Server can be configured to work around this host problem by setting the
NO400D registry value as defined below. However, even with this option set, SNA
Server still does not allow an LUA (RUI or SLI) application to set the CD bit on
a full duplex LU0 session, since this is a protocol violation.

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

When a host application initiates an LU0 session with full duplex send/receive
mode (by setting bit 0-1 to "00" in Byte 7 of the BIND message), this indicates
that the Change Direction (CD) bit is not to be used on the session. The Change
Direction bit is only used on half-duplex sessions to indicate which end has
direction to send on a session.

However, some host applications may still set the CD bit on a full duplex
session, though this is a protocol violation. However, it may not be possible to
fix the host application, so SNA Server will ignore this message by enabling the
following registry key:

  HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/ 
  SnaServr/Parameters/ 

  NO400D: REG_SZ: YES

This causes SNA Server to ignore any messages received on an LU0 full duplex
session which has the CD bit set. However, the LUA (RUI or SLI) application
running on SNA Server is still not allowed to set the CD bit when sending
messages to the host on a full duplex LU0 session, since this is a protocol
violation.

Additional query words:

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Keywords          :  
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ211 kbSNAServ211SP1
Version           : WINDOWS:2.11,2.11 SP1,3.0
Issue type        : kbinfo

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