TN3270: Unbind Hold Causes TN3270 Client 505 Error

• Microsoft SNA Server, versions 2.11, 2.11 SP1
  on the following platforms: NT

SYMPTOMS

When you log onto a host system through the SNA Server version 2.11sp1 TN3270E service, the TN3270 user may receive a 505 error and lose his or her session.

If this occurs, the SNA Server TN3270E service will log the following events into the Microsoft Windows NT application event log:

• Event 601
  TN3270(E) session established with client at xxx.xxx.xxx.xxx (port xxxx) using LU LAA9.



• Event 309
  WRITE failed with LUA_STATE_CHECK / LUA_MODE_INCONSISTENCY for xxx.xxx.xxx.xxx (port xxxx).



• Event 603
  TN3270(E) session with client at xxx.xxx.xxx.xxx (port xxxx) using LU LAA9 terminated abnormally because: TN3270E Service Error 505



• Event 3065
  A Bind sent by the host for a 3270 session was rejected



• Event 902
  Logic error in module SNASessionTerminate identified by:.SNAWriteBuffersInUse

CAUSE

When a 3270 user tries to access a host application through a host session manager, the session manager typically sends an UNBIND(bind forthcoming, or 0x02) followed by a BIND from the host application that was requested.

The TN3270 server was not properly handling the UNBIND, which was causing its LUA RUI_WRITE call to fail. Therefore, it caused the TN3270 server to end the session. However, the TN3270 server now correctly ignores this error.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 2.11 and 2.11.sp1.
This problem was corrected in the latest Microsoft SNA Server 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

MORE INFORMATION

The host sends a data message, followed by an UNBIND (bind forthcoming). The TN3270 Server issues a response to the data message. However, by that point the RUI library has received the UNBIND (bind forthcoming) request, and has switched states to Session Terminating state. In this state it rejects the response message from the TN3270 Server, with the error LUA_STATE_CHECK / LUA_MODE_INCONSISTENCY.

Additional query words: prodsna sp1

Keywords : kbnetwork ntnetserv kbbug2.11 kbfix2.11.sp2
Version : WINDOWS:2.11,2.11 SP1
Platform : WINDOWS
Issue type :