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From: andrew@jhereg.osa.com (Andrew C. Esh)
Newsgroups: comp.dcom.lans
Subject: Re: 10BaseT installation
Summary: This is correct.
Message-ID: <1991Apr9.143743.4612@jhereg.osa.com>
Date: 9 Apr 91 14:37:43 GMT
Article-I.D.: jhereg.1991Apr9.143743.4612
References: <1991Apr5.105804.24270@hellgate.utah.edu>
Sender: Andrew C. Esh
Organization: Open Systems Architects, Inc., Mpls, MN
Lines: 36

In article <1991Apr5.105804.24270@hellgate.utah.edu> zeleznik@cs.utah.edu (Mike Zeleznik) writes:
>>
>>AT&T uses some more pins to include some other features, like
>>SQE-testing and link integrity testing. I really don't know, if 
>>those features are part of the 10 Base T - standard.
>>
>>Rgds Rainer
>
>Are they using the extra pins to remotely control these features of the
>transceiver?  Otherwise, I don't see the need for more lines/pins.
>
>I thought that link integrity is handled simply by transmitting a
>low-duty-cycle pulse on the xmit pair when there is no other activity, and
>seeing if it comes back on the receive pair.  This would not require any
>additional lines/pins.
>
>The SQE signal, and the integrity test of its line, occur on the other side
>of the transceiver, so how would this require more lines/pins on the
>physical network?
>
>Mike
>
>  Michael Zeleznik    zeleznik@cs.utah.edu    801-581-5617

As far as I know, the above is correct. As a matter of fact, the Link Pulse
is required in order to conform to the 10baseT spec. A hub that is in spec
will not work with a transceiver that either does not do the link pulse, or
has it turned off. "Twisted Pair" tranceivers, which are pre-10baseT will
not work with the new hubs. All this occurs on pairs 1-2, 3-6 only, since
that's all we bothered to punch down here. :-)

-- 
Andrew C. Esh			andrew@osa.com
Open Systems Architects, Inc.
Minneapolis, MN 55416-1528
(612) 525-0000			Practicing the OSI Standard