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Date:      Sat, 27 Sep 1997 09:47:15 -0700 (PDT)
From:      "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
To:        sthaug@nethelp.no
Cc:        tlambert@primenet.com, hackers@FreeBSD.ORG, stable@FreeBSD.ORG
Subject:   Re: 'fxp' driver/hardware lossage (was Re: Alexander B. Povol's mail)
Message-ID:  <199709271647.JAA20293@GndRsh.aac.dev.com>
In-Reply-To: <17057.875363985@verdi.nethelp.no> from "sthaug@nethelp.no" at "Sep 27, 97 02:39:45 pm"

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> > > That's only true of coaxial media.  Over twisted pair, if you see
> > > data start arriving on the receive pair while your transmitting then
> > > you have to assume that the data is being sent by another station
> > > and you've got a collision situation.
> > 
> > Isn't this the hub's responsibility to distinguish and prevent?
> 
> Nope. A hub doesn't do anything with collisions - it just propagates
> them bit by bit. The NICs sense the collision.

Better go think so more about that... it depends on the hub!  Some hubs
that have partitioning ability will automagically partition out someone
who starts to transmit if the hub is sending data out that port, this
is called autopartitioning and is used to stop baligerant (sp) mau's
or Jabberers(sp).

If you want something that really tries to ``prevent'' this you want
a switch and not a hub, and you want full-duplex non-simplex NIC cards
in every box connected to that switch, and no I'm not just talking
about 100Base stuff here, it applies to both 10 and 100Base ethernet
over TP.

-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation, Inc.                   Reliable computers for FreeBSD



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