TN3270 Client Sessions Fail with sec_rc=0x00000320 (LUA_BRACKET)

• Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0, 4.0 SP1, 4.0 SP2

SYMPTOMS

TN3270(E) Clients may intermittently lose their session to the host application. When the failure occurs, the emulator may display a message indicating a "BRACKET ERROR" was encountered; the actual format of the message will vary depending on the TN3270(E) emulator being used.

SNA Application LUA API traces gathered during an occurrence of the failure indicate the following return codes on the failed session :prim_rc=0x1400 (LUA_UNSUCCESSFUL) sec_rc=0x00000320 (LUA_BRACKET).

Additionally, the Windows NT application event log shows the following events at the time the failure occurred:

EventID : 603
Source : TN3270 Server
Description : TN3270(E) session with client at xxxx.xxxx.xxxx.xxxx (port xxxx) using LU ABCD terminated abnormally because:
TN3270E Service Error 505
SNA API verb WRITE failed. Failure described as:
RUI Write verb has completed with primary rc of Unsuccessful and secondary rc of Bracket Protocol Error.
Explanation : A TN3270(E) client session was terminated abnormally

EventID : 309
Source : TN3270 Server
Description : WRITE failed with LUA_UNSUCESSFUL / LUA_BRACKET for xxxx.xxxx.xxxx.xxxx(port xxxx)
Explanation : An SNA API call failed

CAUSE

BIND negotiation during the client's session Setup determine that Conditional Bracket Termination is used as the Bracket protocol on the session.

In accordance with this protocol and as defined in the SNA formats specification, SNA Server is rejecting a new Begin_Bracket data message from the client emulator because TN Server hasn't acknowledged an earlier End_Bracket request sent to the client, which requires a definite response.

Please refer to the IBM SNA Formats manual (GA27-3136)for further details.

RESOLUTION

To resolve this problem, obtain the latest service pack for SNA Server version 4.0. For additional information, please see the following article in the Microsoft Knowledge Base:

Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server version 3.0,SP1, SP2, SP3, Microsoft SNA Server version 4.0, SP1 and SP2. This problem was first corrected in SNA Server version 4.0 Service Pack 3.

Additional query words:

Keywords : sna4sp3fix sna3 sna3sp1 sna3sp2 sna3sp3 sna4 sna4sp1 sna4sp2
Version : WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,3.0 SP4,4.0,4.0 SP1,4.0 SP2
Platform : WINDOWS
Issue type : kbbug