Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!wuarchive!texbell!vector!telecom-gateway
From: idacom!danny@uunet.uu.net (Danny Wilson)
Newsgroups: comp.dcom.telecom
Subject: Re: ISDN Subscriber Equipment
Message-ID: 
Date: 25 Sep 89 19:19:52 GMT
Sender: news@vector.Dallas.TX.US
Organization: IDACOM Electronics Ltd., Edmonton, Alta.
Lines: 30
Approved: telecom-request@vector.dallas.tx.us
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@vector.dallas.tx.us
X-TELECOM-Digest: volume 9, issue 406, message 11 of 12

In article , fff@mplex.UUCP
(Fred Fierling) writes:

> Assuming this is correct, I understand that it would be possible for two
> independent calls to be handled on each of the B channels.  So, how would
> both telephones perform call set up and tear down on the one D channel?

If you have two TE's on a single S/T bus (point to multipoint operation)
there are two addressing schems that come into play.

At the physical level, the S/T bus has a collision handling mechanism
that restricts access to the bus to only one TE at a time.

The NT (or switch) assigns a TEI (Terminal Endpoint Identifier) to
each terminal device on the bus.  TEI's can either be manually
assigned by the service technician (dip switches etc) or can be
assigned dynamically by management procedure software resident on the
switch.

Since the switch is aware of which TE is negotiating for a call it can
assign one B-Channel to each TE device.

In fact, in a multi-mode terminal, several calls can be
active/suspended at one time, with each call having a distinct Layer 3
call reference value.

Danny Wilson
IDACOM Electronics		danny@idacom.uucp
Edmonton, Alberta		{att, watmath, ubc-cs}!alberta!idacom!danny
C A N A D A