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Date:      Wed, 7 Oct 1998 21:59:09 +0200 (CEST)
From:      Andre Albsmeier <andre.albsmeier@mchp.siemens.de>
To:        luigi@labinfo.iet.unipi.it (Luigi Rizzo)
Cc:        hackers@FreeBSD.ORG
Subject:   Re: How to send data between two network cards directly?
Message-ID:  <199810071959.VAA02775@internal>
In-Reply-To: <199810071518.QAA08692@labinfo.iet.unipi.it> from Luigi Rizzo at "Oct 7, 1998  4:18:42 pm"

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> > > > together via 10Base2. I would like to send data from one
> > > > machine two the other without doing IP or any other
> > > > protocol.
> ...
> > OK, maybe I desribed it in a wrong way. I would like to use
> > the most basic protocol that is available. No overhead,
> > no error correction, no nothing...
> ...
> > I have got two wireless-lan-like developer boxes. They got each an UTP
> > port and transmit data via a direct spread spectrum frequency hopping
> > protocol. We have two compare their performance, errors and reliabilty
> > with other, for example RS232 or S0 bus based, boxes. They run the ethernet
> > protocol (ok, this is the lowest level protocol, I have to use) and I would
> > like to transmit data without running TCP,UDP or something else.
> 
> then for your purposes, UDP or raw ethernet packets are absolutely
> equivalent.

I think I will stick with the raw packets first and see how it is 
working. I still don't know exactly what I have to expect
since I don't have much infos about the internal of these
boxes. These are only some experimental test and, as you can
imagine, I will have to do some comparisons with the RS232 and S0
bus stuff so it's actually comparing apples with pears as
we say in germany :-)

> 
> if you really want to see things in detail you might try to disable UDP
> checksums (i think this is a socket-level option, isn't it ?)
> or even pass up bad frames from the ethernet driver (either
> use bpf, or play with the ethernet driver)

Yes the bpf was also coming on my mind but I still haven't got
much experience with it (from a programers point of view) and
I have to get this thing running in a short time.

> 
> 	cheers
> 	luigi

Thanks a lot for your help,

	-Andre

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