Date: Tue, 25 May 1999 10:45:44 +1200 From: "Craig Harding" <crh@outpost.co.nz> To: freebsd-isdn@freebsd.org Subject: Re: ISDN Terminal adapter no work Message-ID: <19990524224615.1721B14CF9@hub.freebsd.org> In-Reply-To: <xzppv3ql6z1.fsf@localhost.ping.uio.no> References: Bart van Leeuwen's message of "Mon, 24 May 1999 19:01:06 %2B0200 (CEST)"
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Dag-Erling Smorgrav wrote:
> There was never talk of using two 33k6 modems instead of an ISDN
> line. Somebody claimed that an ISDN TA was a "very fast modem", to
> which I replied that the difference was not large enough to warrant
> the use of the word "very".
I'm that someone, and although it seems a pointless semantic
argument, I would think 128k is "very" much faster than 56k (the
fastest available modem speed at present) and 128k is what my TA runs
at.
What I was actually trying to say in my original message (and which I
thought was reasonably clear) is not that ISDN TA's are necessarily
very fast, just that to use one on a FreeBSD box you merely have to
think of it as a modem, albeit one that's faster than a normal analog
modem. The Zyxel Omninet I have only has a single serial port to the
DTE so the comparison seems valid.
The other point I made, which I'll reiterate here for the benefit of
other people new to ISDN and Terminal Adaptors and the like (as I
was 3 weeks ago) is that (and this only applies for certain to the
Zyxel Omninet but I believe is true in the general case) to use the
multi-link PPP modes of the TA, you don't have to do anything
special to talk to it from a FreeBSD box. I use usermode PPP, and to
enable both B channels on the TA to my ISP I merely use the normal
AT command setup in PPP's config files to enable multi-link PPP
inside the Terminal Adaptor. Apart from that, PPP is configured to
talk to the ISP as if the Terminal Adaptor is a normal modem, and
the Terminal Adaptor internally performs some kind of transparent
single-link PPP to multilink PPP translation that makes everything
Just Work.
The Zyxel supports V.120 channel bonding as well, but my ISP doesn't.
I really wanted to explain all this here so that it'll get into the
list archives so the next person in my position trying to get a
handle on these terminal adaptors and their multi-link PPP
capabilities won't be as flummoxed as I was.
An additional tip - definitely enable LQR monitoring as the ISDN line
can disconnect without the TA bothering to tell the FreeBSD box
about it.
-- C.
--
Craig Harding Head of Postproduction, Outpost Digital Media Ltd
"I don't know about God, I just think we're handmade" - Polly
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