DOCUMENT:Q131865 23-JUN-1995 [winnt] TITLE :SMC Elite Ultra NIC Causes UNIX Computers to Disconnect TCP/IP PRODUCT :Microsoft Windows NT PROD/VER:3.11 3.50 3.51 OPER/SYS:WINDOWS KEYWORDS:kbnetwork kb3rdparty kbhw kbbug3.50 kbfix3.50 ---------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation versions 3.5 and 3.51 - Microsoft Windows NT Server versions 3.5 and 3.51 - Microsoft TCP/IP-32 for Windows for Workgroups, versions 3.11, 3.11a, and 3.11b ---------------------------------------------------------------------- SYMPTOMS ======== TCP/IP connections between two UNIX computers or between a Microsoft network computer and UNIX computer are lost. This happens on a network with both UNIX computers and a computer running a Microsoft protected mode TCP/IP protocol stack (including TCP/IP-32 versions 3.11, 3.11a, and 3.11b and Windows NT versions 3.5 and 3.51) and where the Microsoft network computer is using the SMC Elite Ultra network interface card (NIC). CAUSE ===== The SMC Elite Ultra NIC incorrectly passes up ethernet packets addressed to other computers. This causes the Microsoft TCP/IP protocol stack to send an ICMP Host Unreachable message back to the source computer. Some UNIX TCP/IP stacks disconnect when they receive this ICMP packet. WORKAROUND ========== To work around the SMC hardware problem, Microsoft has removed the code from the protected mode TCP/IP stack which sends the ICMP Host Unreachable message under these circumstances. Versions of the Windows NT file, TCPIP.SYS, date stamped 6/14/95 or later incorporate the above workaround. Versions of the Windows for Workgroups TCP/IP-32 file, VIP.386, date stamped 7/19/95 or later incorporate the above workaround. This workaround is also included in the release version of Windows 95. STATUS ====== Microsoft has confirmed this to be a problem while using Windows NT versions 3.5 and 3.51 and Windows for Workgroups TCP/IP-32 versions 3.11, 3.11a, and 3.11b. A workaround to this problem is in development, but has not been regression-tested and may be destabilizing in production environments. Microsoft does not recommend implementing this workaround at this time. This workaround is available from Microsoft Product Support Services as well as electronically by "anonymous" ftp at: ftp://ftp.microsoft.com:/bussys/winnt/winnt-unsup-ed/fixes/nt35/icmpfix -and- ftp://ftp.microsoft.com:/bussys/winnt/winnt-unsup-ed/fixes/nt351/icmpfix -and- ftp://ftp.microsoft.com:/bussys/clients/wfw/tcpip32-fixes/icmpfix The Elite Ultra is manufactured by SMC, a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability. Additional reference words: prodnt 3.11 3.50 3.51 sniper KBCategory: kbnetwork kb3rdparty kbhw kbbug3.50 kbfix3.50 KBSubCategory: nttcp nthw ntdriver ============================================================================= 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 1995.