DOCUMENT:Q216303 16-MAY-2002 [winnt] TITLE :Incorrect NDIS Filtering of Some Ethernet Multicast Frames PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 OPER/SYS: KEYWORDS:kbWinNT400sp5fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== Some Ethernet multicast frames may be incorrectly identified as Ethernet broadcast frames by the filtering logic in Ndis.sys. Consequently, these multicast frames are not always delivered as expected to NDIS packet drivers and higher layers of the network stack. CAUSE ===== Ethernet multicast frames are distinguished from directed packets by having the Individual/Group (I/G) bit of the destination address set to 1 (Group). The Ethernet broadcast address is defined to be 0xFFFFFFFFFFFF, which is a special case of Ethernet multicast address. Frames with an Ethernet multicast destination address whose first byte was 0xFF were being incorrectly identified and treated as broadcast frames. WORKAROUND ========== To work around this problem, choose an Ethernet multicast addressing scheme that does not include Ethernet multicast addresses whose first byte is 0xFF. RESOLUTION ========== To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to: - http://www.microsoft.com/Windows/ServicePacks/ -or- - Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS STATUS ====== Microsoft has confirmed this to be a problem in Windows NT 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5. Additional query words: 4.00 ====================================================================== Keywords : kbWinNT400sp5fix Technology : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 Version : winnt:4.0 Hardware : ALPHA x86 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 2002.