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Q140829: TN3270 Clients Do Not Accept "Do TN3270E"

Article: Q140829
Product(s): Microsoft SNA Server
Version(s): 2.11
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 06-FEB-2002

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The information in this article applies to:

- Microsoft SNA Server, version 2.11, on platform(s):
   - the operating system: Microsoft Windows NT 
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SYMPTOMS
========

"Do TN3270E" is a command sent from the TN3270E Server Service to the TN3270
emulator during session initialization. It asks the TN3270 emulator whether it
can support the TN3270E protocol. Some TN3270 clients do not accept the "Do
TN3270E" message from the TN3270E server. This prevents session establishment
between the TN3270 client and TN3270E Server Service. Sending the "Do TN3270E"
command is a legal command according to RFC 1647."

RFC 1647 states the Following:

"Telnet clients and servers would be free to negotiate support of the TN3270E
option or not. If either side does not support TN3270E, traditional TN3270 can
be used; otherwise, a sub-negotiation will occur to determine what subset of
TN3270E will be used on the session. It is anticipated that a client or server
capable of both types of 3270 emulation would attempt to negotiate TN3270E
first, and only negotiate traditional tn3270 if the other side refuses
TN3270E."

SAMPLE TRACE
------------

>12/08 11:18:16.828 (+ smidgen )  Event=TEV_Started

>12/08 11:18:30.217 (+ 13 secs )  Event=TEV_DataToClient
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
DO TN3270E
Number of bytes = 3

>12/08 11:18:30.217 (+ smidgen )  Event=TEV_TCPSendIssued
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
Number of bytes = 3
000000  fffd 28                                  !..(             !

>12/08 11:18:30.257 (+ 40 msecs)  Event=TEV_TCPRecvIssued
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4

>12/08 11:18:30.277 (+ 20 msecs)  Event=TEV_TCPSendCompleted
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
Bytes transferred = 3

>12/08 11:19:09.403 (+ 39 secs )  Event=TEV_TCPRecvCompleted
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
Bytes returned = 0

>12/08 11:19:09.423 (+ 20 msecs)  Event=TEV_SessionTerminationScheduled
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
NormalTermination

>12/08 11:19:09.463 (+ 40 msecs)  Event=TEV_SessionTermination
Thread = 0x0000005E  Session = 0x0007A718  Socket = 0x000001B4
Session terminated

RESOLUTION
==========

The TN3270E Server has a new registry entry that can be used to turn off TN3270E
support:

  Subtree:   HKEY_LOCAL_MACHINE
  Key:       \currentcontrolset\services\tn3270\parameters\NoTN3270E
  Type:      REG_EXPAND_SZ
  Value:     ON

When this value is set to ON, the server reverts to being a TN3270 Server. This
registry setting effects all sessions; not just ones from TN3270 emulators.

STATUS
======

This feature is included in the latest U.S. Service Pack for SNA Server for
Windows NT, version 2.11. 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: prodsna

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch
Version           : :2.11
Issue type        : kbbug
Solution Type     : kbfix

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