Date: Sat, 20 Sep 1997 18:42:28 +0200 (CEST) From: torstenb@onizuka.tb.9715.org (Torsten Blum) To: root@bmccane.uit.net (Wm Brian McCane) Cc: gjennejohn@frt.dec.com, hackers@FreeBSD.ORG Subject: Re: ISDN Modems Message-ID: <m0xCSc0-0006hCC@onizuka.tb.9715.org> In-Reply-To: <Pine.BSF.3.91.970920100834.15878B-100000@bmccane.uit.net> from Wm Brian McCane at "Sep 20, 97 10:10:58 am"
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Wm Brian McCane wrote: > Only 7.5kB/sec? I am now very confused. I get 6kB/s throughput from my > 33.6 most of the time. Of course I am usually transferring news/mail so they > are highly compressible. 7.5kB/sec are without compression of course. > Do any of the plug-in cards do LZ compression, or anything similar? Uh, well, compression and ISDN is a different story. V.42bis for example need error correction. In the early days of ISDN here in Germany, some Routers used V.42bis together with LAP-B framing, but IP-in-HDLC framing was more popular, but it did not support V.42bis. PPP-over-ISDN is the standard for transmitting IP over ISDN links. With CCP you can even support more than one compression algorithm. The most common compression alg. used for PPP and ISDN is STAC. Most Routers and Accesss-Server support it. Unfortunately STAC is patented and you have to pay lots of money for a licence. There are other compression algorithms for which even a rfc describes the operation with PPP, but they're not widespread. Ciscos are the only one that support Predictor1 as far as I know. In discussions with people from other manufacturers the answer is always the same: There's no or not enough demand for it. -tb
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