Incorrect NDIS Filtering of Some Ethernet Multicast Frames

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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.
Ethernet multicast frames are distinguished from directed packets by havingthe Individual/Group (I/G) bit of the destination address set to 1 (Group).

The Ethernet broadcast address is defined to be 0xFFFFFFFFFFFF, which is aspecial 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.

To work around this problem, choose an Ethernet multicast addressing scheme that does not include Ethernet multicast addresses whose first byte is 0xFF.
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:
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:
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.

Article ID: 216303 - Last Review: 01/06/2015 04:21:12 - Revision: 3.0

Microsoft Windows NT Server 4.0 Standard Edition

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