Microsoft KB Archive/163208

= Downstream PU Fails to Activate After Short ACTLU Response =

Article ID: 163208

Article Last Modified on 11/26/2003

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APPLIES TO


 * Microsoft SNA Server 2.0
 * Microsoft SNA Server 2.1
 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 2.11 Service Pack 1

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This article was previously published under Q163208



IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SYMPTOMS
When a downstream PU2.0 emulator attempts to activate a session through an SNA Server, SNA Server may never send a NOTIFY (available) request to the host, causing the LU session to fail to activate.

This problem was observed when attempting to configure an ASCII-3270 protocol converter (SyncResearch SDLC/LLC2 converter) to use an SNA Server downstream PU connection.



CAUSE
SNA Server automatically sends NOTIFY (unavailable) when the upstream host connection becomes active, and it depends on the downstream PU2.0 client to send a NOTIFY (available) or a "long" ACTLU response later on. However, some downstream clients do not send a NOTIFY message and send "short" ACTLU responses, and so SNA Server never sends a NOTIFY(available) to the host.



RESOLUTION
An update to Snaservr.exe is available for SNA Server 2.11; the update supports a new registry parameter to correct this problem. This update is newer than SNA Server 2.11 Service Pack 1.

Once you have applied this update, you must also add the following registry entry. This will cause SNA Server to respond to the downstream client connection request. To add the registry entry:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows NT. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.  Start Registry Editor (Regedt32.exe).  Under the HKEY_LOCAL_MACHINE subtree, go to the following subkey:      SYSTEM\CurrentControlSet\Services\SnaServr\Parameters  Tab to the right-hand window and press the  key. In the Add Value dialog box, type:

Value Name: SHORTACTLU

Data Type: REG_SZ

and click OK. In the String Editor dialog box, type:

String:

Once entered, the value will appear in REGEDT32 as follows:

SHORTACTLU: REG_SZ:

 Quit Registry Editor.</li></ol>

The SHORTACTLU registry entry causes SNA Server to respond to the downstream client connection request the above behavior, regardless of the value the entry is set to. When this registry entry is present, SNA Server sends a NOTIFY(available) to the host when it receives a short ACTLU response from the downstream client.

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STATUS
Microsoft has confirmed this to be a problem in SNA Server versions 2.0, 2.1, 2.11, and 2.11 Service Pack 1 (this feature is implemented in 3.0). A supported fix to 2.11 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 dspu

Keywords: kbbug kbfix kbnetwork KB163208

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