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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!feed1.news.erols.com!worldnet.att.net!newsfeed.nacamar.de!fu-berlin.de!irz401!orion.sax.de!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Cheap ISDN solutions [was: What's the state of ISDN support?] Date: 19 Apr 1997 16:36:23 GMT Organization: Private BSD site, Dresden Lines: 23 Message-ID: <5jasa7$h5d@uriah.heep.sax.de> References: <33303AE2.503C@cmr.no> <5gqhjt$k3t$1@gail.ripco.com> <333226A6.ABD322C@freebsd.org> <5hqooq$gtn@ui-gate.utell.co.uk> <33423F01.167EB0E7@net-tel.co.uk> <5hvtj8$e44@ui-gate.utell.co.uk> <139@fridaycs.win-uk.net> <861220198.962@dejanews.com> <3356CAEE.1258@onthenet.com.au> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.6 X-Phone: +49-351-2012 669 X-PGP-Fingerprint: DC 47 E6 E4 FF A6 E9 8F 93 21 E0 7D F9 12 D6 4E Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:39380 Tony Griffiths <tonyg@OntheNet.com.au> wrote: > That is the reason why the same crappy > pair of copper wires can do ISDN Basic rate (2xB+D == 144 Kbps in each > direction) or even ISDN Primary rate (1.5 Mbps in the US, 2 Mbps > elsewhere) as are used for a single analogue telephone call! Btw., the clock rate on the copper wire for a BRI is not 144 kHz, but i think 80 or 90 kHz only. They don't use a binary but a ternary encoding. (The S0 bus clock rate is 192 kHz, but only 144 kbit/s are usable, the remainder is framing overhead.) For PRI, you gotta use 4 wires, echo compensation wouldn't be possible at this rate, and the allowable distance to the next switch/repeater is much shorter than for BRI. Also, IIRC you cannot use all the wire pairs of a cable for PRI. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)