From owner-freebsd-hackers Sat Sep 20 10:02:17 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id KAA15481 for hackers-outgoing; Sat, 20 Sep 1997 10:02:17 -0700 (PDT) Received: from casparc.ppp.net (mail.ppp.net [194.64.12.35]) by hub.freebsd.org (8.8.7/8.8.7) with SMTP id KAA15468 for ; Sat, 20 Sep 1997 10:02:09 -0700 (PDT) Received: from ernie by casparc.ppp.net with uucp (Smail3.1.28.1 #1) id m0xCSuw-000oHXC; Sat, 20 Sep 97 19:02 MET DST Received: from bert.kts.org(really [194.55.156.2]) by ernie.kts.org via sendmail with smtp id for ; Sat, 20 Sep 1997 18:29:43 +0200 (MET DST) (Smail-3.2.0.91 1997-Jan-14 #2 built 1997-Feb-8) Received: by bert.kts.org via sendmail with stdio id for freebsd-hackers@freebsd.org; Sat, 20 Sep 1997 18:21:23 +0200 (CEST) (Smail-3.2.0.94 1997-Apr-22 #7 built 1997-Jul-4) Message-Id: From: hm@kts.org (Hellmuth Michaelis) Subject: Re: ISDN Modems In-Reply-To: from Wm Brian McCane at "Sep 20, 97 10:10:58 am" To: freebsd-hackers@freebsd.org Date: Sat, 20 Sep 1997 18:21:23 +0200 (CEST) Organization: Kitchen Table Systems Reply-To: hm@kts.org X-Mailer: ELM [version 2.4ME+ PL31H (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Wm Brian McCane wrote: > > I can get (depending on the quality of the connection) the maximum > > throughput of ~8kB/sec (well, actually ~7.5kB/s with overhead). [...] > Only 7.5kB/sec? I am now very confused. An ISDN B-channel has a maximum transfer rate of exactly 8 kB/sec. Using ftp over such a line ends up with something close to 7.5 kB/sec uncompressed. > Do any of the plug-in cards do LZ compression, or anything similar? Some active ISDN cards do compression, for some time it seemed V.42 were the standard the manufacturers would agree upon, but they didn't. (if i recall it correctly, V.42 compresion is supported under V.120, but i'm not shure). There is no standard interoperable way of doing compression on the B-channel, many proprietary solutions exist; the only standard in this environment is doing PPP over ISDN which gives you the usual (some also proprietary, i.e. STAC compression) compression schemes. hellmuth -- Hellmuth Michaelis hm@kts.org Hamburg, Europe "Those who can, do. Those who can't, talk. And those who can't talk, talk about talking." (B. Shaw)