Re: Dealing with M_HASFCS for protocols that do not do ethernet crc

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> I thought the frame check CRC was part of the Ethernet spec, and, as
>> such, was not an optional part of any Ethernet packet - on a par
>> with source and destination MACs or the two-byte next-protocol
>> value.
> Yes, but only since 802.3.  There were various protocols used over
> ethernet before that standard finalized.

Ah!  Thank you - I was not aware there were intermediate steps that (a)
lacked FCS and (b) were widely enough releaesd to have protocols NetBSD
cares about built atop them.

But, that just changes my question.  Now that the world _has_ settled
on 802.3, why are the previous steps relevant?  It sounds to me as
though FCSless protocols cannot run on 802.3 networks (because the
latter mandate FCS); nor does it sound as though pre-FCS hardware can
interoperate with 802.3 hardware (in one direction, most packets will
be dropped because payload is taken as FCS; in the other, "garbage"
data will be appended).  But, if those are true, I can't see how any of
the pre-FCS stuff could be relevant at all.

So, I'm obviously still missing something important.  What?

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