Microsoft KB Archive/216303

= Incorrect NDIS Filtering of Some Ethernet Multicast Frames =

Article ID: 216303

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q216303



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-


 * 152734 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/directory/overview.asp



STATUS
Microsoft has confirmed that this is 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: kbhotfixserver kbqfe kbbug kbfix kbqfe KB216303

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