Path: utzoo!dptcdc!jarvis.csri.toronto.edu!mailrus!purdue!decwrl!labrea!Portia!jessica.stanford.edu!morgan
From: morgan@jessica.stanford.edu (RL "Bob" Morgan)
Newsgroups: comp.dcom.lans
Subject: 10BaseT operation, spec?
Message-ID: <1627@Portia.Stanford.EDU>
Date: 17 Apr 89 19:27:25 GMT
Sender: USENET News System <news@Portia.stanford.edu>
Reply-To: morgan@jessica.stanford.edu (RL "Bob" Morgan)
Organization: Stanford University
Lines: 34


I'm puzzled by various references I've seen recently, in this forum
and elsewhere, to the operation of the proposed 10BaseT Ethernet.  Is
the draft spec available from anywhere, either on paper or (better)
on-line?  Is there some nice, descriptive article somewhere that talks
about 10BaseT operation and terminology?

When the battle to define the standard was going on last year, I
thought there was a clear split between the "3Com approach" and the
"Lattisnet approach."  The 3Com method involves simply modifying the
standard Ethernet transmission to work acceptably over twisted pair,
more or less like a Balun does for other coax-to-TP purposes.  In this
case the TP is really just an Ethernet cable, the transceiver
functions are performed at the station, and the machinery in the
wiring closet is just a multiport repeater with one Balun per port.
The Lattisnet method, on the other hand, uses the TP as an extension
of the transceiver cable, so that most (some? all?) transceiver
functions are performed by the wiring-closet machinery, which is
more-or-less a multiport transceiver.  The device at the station is
required to multiplex the signals that are normally carried on the
multiple-conductor transceiver cable so they'll fit on the TP, but
isn't really a transceiver in the normal sense.  There is no repeater
in the normal sense (auto-partitioning, retiming, etc) at all.  

Of course, the Lattisnet approach "won" the standards battle.  Now,
I've seen people referring to the 10BaseT wiring closet device as a
repeater.  Is this just loose terminology or is my understanding of
10BaseT/Lattisnet wrong?

Thanks,

 - RL "Bob" Morgan
   Networking Systems
   Stanford