Date: Mon, 24 May 1999 11:54:02 -0700 (PDT) From: Tom <tom@uniserve.com> To: Bart van Leeuwen <bart@ixori.demon.nl> Cc: Dag-Erling Smorgrav <des@flood.ping.uio.no>, isdn@freebsd.org, blitz@pdq.net, stable@freebsd.org Subject: Re: ISDN Terminal adapter no work Message-ID: <Pine.BSF.4.02A.9905241152190.29433-100000@shell.uniserve.ca> In-Reply-To: <Pine.BSF.4.05.9905241851250.1785-100000@ixori.demon.nl>
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On Mon, 24 May 1999, Bart van Leeuwen wrote: > On Mon, 24 May 1999, Tom wrote: > > > On 24 May 1999, Dag-Erling Smorgrav wrote: > > > > > "Craig Harding" <crh@outpost.co.nz> writes: > > > > Most TA's act just like very fast modems. > > > > > > "very" is perhaps not the right word, since an single ISDN channel is > > > less than twice as fast as a 33k6 modem. > > > > Nope. > > > > First of all, most everyone gets 2B+D ISDN (2 x 64K) anyhow, in fact > > 1B+D (64k) isn't available in most areas of the world. > > > > Second, ISDN is sync, but modems are async. Now some people use various > > async emulation protocols over ISDN (like V.120), but that is a complete > > waste, especially if all you are doing is PPP. > > > > Here is what is looks like: > > > > 64k ISDN channel: 64000 / 8 = 8000 bytes/sec > > 2 x 33.6 modem: 67200 / 10 = 6720 bytes/sec > > > > Uusually async modems also support things like mnp4 and 5, v42, > v42bis etc. one of the results of this is that the actual transport of Yes, I didn't include that. Nor did I not include using STAC compression on the ISDN line. STAC provides much better results than any modem compression protocol. ... > So... this is only true for a async connection employing 2 plain async > modems without any error correction and such, which are almost > extinct nowadays. So is a bare ISDN connection. Tom To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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