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From: Don Lewis <Don.Lewis@tsc.tdk.com>
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Date: Sat, 27 Sep 1997 01:11:51 -0700
In-Reply-To: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
       "Re: 'fxp' driver/hardware lossage (was Re: Alexander B. Povol's mail)" (Sep 26, 11:10pm)
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To: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>, dg@root.com
Subject: Re: 'fxp' driver/hardware lossage (was Re: Alexander B. Povol's mail)
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On Sep 26, 11:10pm, "Rodney W. Grimes" wrote:
} Subject: Re: 'fxp' driver/hardware lossage (was Re: Alexander B. Povol's m
} >    You can't send a packet to yourself under normal circumstances (ethernet
} > is a simplex device).
} 
} Only broken NIC chips are simplex, even the 82586 is actually capable
} of hering itself talk on the wire, though most drives do not set
} the chip into this mode.  Either way ``ethernet is _not_ a simplex
} device''.

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.  However, you may have the option
to loop back your transmitted data to your receiver after the receiver
stage where collision sensing is done.  I believe this is known as
natural loopback.  I don't think it's commonly used.