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