TN3270 Clients Do Not Accept "Do TN3270E"

• Microsoft SNA Server, version 2.11
  on the following platforms: NT

SUMMARY

"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 

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 ntnetserv kbbug2.11
Version : WINDOWS:2.11
Platform : WINDOWS
Issue type :