DOCUMENT:Q160576 13-JUN-2001 [sna] TITLE :3270 Sessions Unexpectedly Return to SSCP Screen PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:2.0,2.1,2.11,3.0,4.0 OPER/SYS: KEYWORDS:kbnetwork ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 4.0, on platform(s): - the operating system: Microsoft Windows NT ------------------------------------------------------------------------------- SYMPTOMS ======== SNA Server clients using 3270 display sessions are returned to the SSCP (VTAM Signon) screen unexpectedly while actively working in a host application. The SNA Server may log one or more of the following events in the Windows NT Application Event Log when this problem occurs: Event ID: 4 Source: SNA Server Description: (1133) Message Sequence Error EXPLANATION The SNA server (node) received an invalid or unexpected message from a remote node on an SNA session. The remote system has a possible configuration or internal logic error. SUBCODE INFORMATION X'1133' The node received a request with an invalid sequence number. Event ID: 12 Source: SNA Server Description: (1118) Negative Response from Remote System (SENSE = 200D) SUBCODE INFORMATION X'1118' The local SNA server (node) received an SNA negative response on an SNA session from a remote system, which indicates a protocol violation by the 3270 emulator. The SNA sense code shown gives details of the type of error. See "IBM Systems Network Architecture: Formats" for an explanation of the sense code. Event ID: 13 Source: SNA Server Description: (1141) Message Sequence Error (SENSE = 2001) EXPLANATION The SNA server (node) received an invalid or unexpected message from a remote node during an SNA session. The cause is probably a logic error in the remote system. The SNA sense data shown gives details of the type of error. SUBCODE INFORMATION X'1141' Session-level protocol violation in an SNA message from the partner LU. CAUSE ===== This has only been reported on SNA Servers with 802.2 connections to IBM 3174 Control Units on Ethernet networks. The problem occurs because a 3174 Ethernet gateway may send a duplicate SNA sequence number to the SNA Server when the 3174 is handling an SNA frame between 1490 and 1493 bytes in size. This leads to a condition where a frame may be re-sent by the 3174 causing the symptoms discussed previously. In addition, the problem only occurs if the 3174 is running 3174 Microcode Level C6.1 or C6.2. RESOLUTION ========== A fix for this problem is available from IBM. Contact IBM support and request IBM 3174 PTR #B27E. MORE INFORMATION ================ For information about how to contact IBM, query in the Knowledge Base for one of the following articles: Q65416 Hardware and Software Third-Party Vendor Contact List, A-K Q60781 Hardware and Software Third-Party Vendor Contact List, L-P Q60782 Hardware and Software Third-Party Vendor Contact List, Q-Z The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability. Additional query words: prodsna ====================================================================== Keywords : kbnetwork Technology : kbAudDeveloper kbSNAServSearch Version : WINDOWS:2.0,2.1,2.11,3.0,4.0 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.