Re: [oc] Ethernet core

[Kent Dahlgren <kent@praesum.com>]

>
>On Mon, 3 Apr 2000, Kent Dahlgren wrote:
>
> >
> > The MAC would not use the length/type field so it doesn't make any 
> difference.
> > The MAC gets it's information about the length of the frame from the 
> physical
> > layer or from the host DMA mechanisms.
> >
>         Can you explain to me how the physical layer or the host DMA
>         mechanisme get information about the length of the frame for any
>         ethernet frame format ?
>
>Regards,
>Novan Hartadi

In the case of frames that are incoming from the physical layer this 
indication would
be the Data Valid signal on the MII interface. Similar indications are 
provided on the
other common and or standard PHY interfaces.

In the case of the host interface this would be whatever signal or other 
event that
indicates that the last byte of the frame has been transferred. There are 
numerous
ways of doing this including having an explicit byte count in the buffer 
descriptors.

Kent
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