Q140826: TN3270 Server Rejects First Data RU After Host’s CLEAR Message
Article: Q140826
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.1,2.11
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 2.1, 2.11
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SYMPTOMS
========
A host application, such as TeleView, allows a user at a terminal to make a
connection and then spawn additional sessions on the SNA host. Under normal
conditions, the user may terminate a session with no further incident. In this
case, however, when a user ends even just one session, the rest of the sessions
are terminated. This condition may occur when running the TN3270 Service for
Windows NT. The TN3270 Server may also generate the following error:
sense data = 081B0000
The IBM Systems Network Architecture (SNA) Formats guide provides the following
information regarding this error:
081B0000
Receiver in Transmit Mode:
A race condition exists: a normal-flow request was received while the
half-duplex contention state was NOT-RECEIVED, or while resources (such
as buffers) necessary for handling normal-flow data were unavailable.
Contrary to the explanation given in the IBM SNA Formats guide, a race condition
does not exist in this case. The error is exhibited in the following diagnostic
tools:
From the Application Log:
Event ID: 309
INIT failed with LUA_COMM_SUBSYSTEM_NOT_LOADED / LUA_SEC_RC_OK for
<IP_address> (port <port_number>).
Event ID: 603
TN3270 session with client at <IP_address> (port <port_number>) using LU
<LU_name> terminated abnormally because:
TN3270 Service Error 505
SNA API verb INIT failed.
Failure described as:
SNA Server has not been started.
Event ID: 698
Invalid Destination L-value. Parameter: 0, Message: 0, Valid range
<range>
Event ID: 699
Invalid message: MsgType 31, MhType 31
Event ID: 1955
RUI_INIT failed for LU, primary_rc=4f0, secondary_rc=0
From an SNA Server API Trace:
...
... RUI ---------------------------------------------- 13:50:43.15
... RUI RUI_READ request
...
... RUI ---------------------------------------------- 13:50:43.56
... RUI RUI_READ response
... RUI OK - OK
...
... RUI ---------------------------------------------- 13:50:43.57
... RUI RUI_WRITE request
...
... RUI ---- Data at address 00119CC4 ----
... RUI 081B0000 <.... >
... RUI ---------------------------------------------- 13:50:43.65
... RUI RUI_WRITE response
... RUI OK - OK
...
... RUI ---- Data at address 00119CC4 ----
... RUI 081B0000 <.... >
...
From a TN3270 Server Trace:
...
>11/27 13:50:43.062 (+ smidgen ) Event=TEV_DataToSNA
Thread = 0x000000C3 Session = 0x0026B7D0 Socket = 0x0000017C
VCB address=0x0026B9D8
verb_length=0x0044 verb=0x0052 (RUI) opcode=0x8004 (WRITE)
sid=0x00010006 correlator=0x0026B7D0 post_handle=0x00000198
prim_rc=LUA_OK sec_rc=LUA_SEC_RC_OK
lu_norm lua_data_length=0x00000004
TH Only efi=0 oadi=0 daf=FD oaf=01 snf=0001
RH -RSP FMD fi=0 sdi=0 bci=1 eci=1 (Only)
83 91 80 dr1=1 dr2=0 ri=1 qri=0 pi=1
bbi=1 ebi=0 cdi=0 csi=0 edi=0 pdi=0
000000 081b0000 *.... *
...
>11/27 13:50:43.562 (+ smidgen ) Event=TEV_DataToSNA
Thread = 0x000000C3 Session = 0x0026B7D0 Socket = 0x0000017C
VCB address=0x0026B9D8
verb_length=0x0044 verb=0x0052 (RUI) opcode=0x8004 (WRITE)
sid=0x00010006 correlator=0x0026B7D0 post_handle=0x00000198
prim_rc=LUA_OK sec_rc=LUA_SEC_RC_OK
lu_norm lua_data_length=0x00000004
TH Only efi=0 oadi=0 daf=FD oaf=01 snf=0002
RH -RSP FMD fi=0 sdi=1 bci=1 eci=1 (Only)
87 91 20 dr1=1 dr2=0 ri=1 qri=0 pi=1
bbi=0 ebi=0 cdi=1 csi=0 edi=0 pdi=0
000000 081b0000 *.... *
...
CAUSE
=====
After receiving a CLEAR message from the SNA host, the TN3270 Server may reject
the first data response unit (RU) from the SNA host. There are two issues here,
both of which have now been fixed:
1. When the TN3270 Server receives a CLEAR message from the SNA host, it does
not reset its internal state which keeps track of whether the TN3270 emulator
or the host application has permission to send. This causes the TN3270 Server
to reject the first data message received from the SNA host with a sense data
= 081B0000, because the TN3270 Server assumes that the TN3270 emulator still
has the permission to send. The TN3270 Server then rejects the next data
message from the host. At this point, the host application gives up and
terminates the session.
2. When the node receives data from the host application which it believes to be
out of bracket it passes a message up to a Request Unit Interface (RUI)
application with the Sense Data Included Indicator (sdi) bit set. On
receiving this, the RUI application is supposed to send a negative response
with the sense data which the node passed up to it. The TN3270 Server,
however, was not checking for this bit.
RESOLUTION
==========
Microsoft has updated the files, TN3NTMSG.DLL and TN3SERVR.EXE, to correct this
problem.
STATUS
======
Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This
problem was corrected in the latest SNA Server for Windows NT, 2.11 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: prodsna
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Keywords :
Technology : kbAudDeveloper kbSNAServSearch kbSNAServ211 kbSNAServ210
Version : WINDOWS:2.1,2.11
Issue type : kbbug
Solution Type : kbfix
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