Ndis 6 MUX IM Sample is not using BackFill for adding VLAN tag in thesent packets

Discussion in 'Windows Vista Drivers' started by Arunkumar Sundaram, Jul 8, 2008.

  1. Arunkumar Sundaram

    Arunkumar Sundaram Guest

    Hi All,

    Why MUX IM is not using DataBackFillSize and request VLAN tag header
    size in backfill? Instead it is allocating from look aside list every
    time there is a send call. This seems to be inefficient. Any Ideas?

    Thanks
    Arun
     
    Arunkumar Sundaram, Jul 8, 2008
    #1

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  2. Arunkumar Sundaram

    Alireza Dabagh [MS] Guest

    Trying to use backfill using "retreat" operation on the NET_BUFFER could
    lead to a fragmented MAC header because there is no guarantee that there is
    any backfill space left. Many NICs out there might not be able to handle a
    MAC header with the first 4 bytes in one buffer and the remaining of the MAC
    header in another buffer.

    So we decided this is better left alone and the real fix is not to do VLAN
    on a NIC that does not handle VLAN in the hardware. In these days it does
    not make sense to write a VLAN driver that has to work with a NIC that does
    not support VLAN tagging and stripping in hardware.

    -ali
     
    Alireza Dabagh [MS], Jul 10, 2008
    #2

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