DOCUMENT:Q189475 22-SEP-1999 [sna] TITLE :Max BTU Size Limit Increased for SNA Server Connections PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1 OPER/SYS: KEYWORDS:kbbuglist ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1 ------------------------------------------------------------------------------- SYMPTOMS ======== The maximum Basic Transmission Unit (BTU) length that can be specified on a connection has been increased to 65,536 bytes for channel connections and 32,768 bytes for non-channel connections. These are limits imposed by SNA XID formats, which allow 2 bytes for maximum BTU size for channel connections and 15 bits for non-channel connections. CAUSE ===== The maximum BTU length was previously hardcoded for a maximum length of 16,393 bytes, which is the largest size supported by Token Ring networks. RESOLUTION ========== Microsoft has confirmed this to be a problem in SNA Server versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, and 4.0 SP1. We are researching this problem in SNA Server version 3.0 and will post more information here in the Knowledge Base as it becomes available. This problem was corrected in the latest SNA Server version 4.0 U.S. Service Pack. For information on obtaining this 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 ================ Setting the maximum BTU length to the limit does not guarantee that the SNA Server connection will actually use this value. The individual link service or the host can negotiate it down. For information on how the actual Max BTU value is determined for 802.2 DLC connection, refer to the following Knowledge Base article: Q148972 How SNA Server Determines Max BTU Over 802.2 DLC Additional query words: snacfg ====================================================================== Keywords : kbbuglist Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2 Version : WINDOWS:3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1 Issue type : kbbug Solution Type : kbfix ============================================================================= 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 1999.