Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!mcvax!unido!altger!korn
From: korn@altger.UUCP (Hans Korneder)
Newsgroups: comp.dcom.modems
Subject: Re: hi speed modems in Germany
Summary: Telebit Modems are great
Message-ID: <1454@altger.UUCP>
Date: 21 Mar 89 12:01:02 GMT
References: <4377@drivax.DRI> <1445@altger.UUCP> <12374@microsoft.UUCP>
Reply-To: korn@altger.UUCP (Hans Korneder)
Organization: Altos Computer Systems Munich
Lines: 76

Some days ago I posted my problem with Telebit Trailblazer modems
(version 4.00 firmware) with satelite links across the ocean.
Meanwhile I've got a solution. To summarize:

In article <12374@microsoft.UUCP> w-colinp@microsoft.uucp (Colin Plumb) writes:
)korn@altger.UUCP (Hans Korneder) wrote:
)> But anyhow: I guess, you won't be very happy with a TB+ across the ocean:
)> The TB-modems do some sort of token passing between the modems when they are
)> idling.  If you dial and get a satellite-line, there are *some* delays on
)> the line, which make it almost impossible for that mechanism to work. (At
)> least those were my experiences).
)
)This seems very odd; I thought the Telebit guys were smarter than this and
)could cope with long-latency lines.  They're certainly aware (uucp spoofing
)an all) of how badly simplistic protocols die in the face of longer
)latency.

They are smarter...


)From: piet@cwi.nl (Piet Beertema):
)	TB's perform excellent on lines thruout Europe; They hardly
)	set up a link across the ocean..
)Not entirely true: that's the case if both sides have
)the 4.0 software revision level; if either side (or
)both) have the 3.0 level it works just fine. Of course
)it suffers from the normal 3.0 drawback: very slow for
)interactive use; but it's fast in batch mode (like uucp).
)Supposedly Telebit has come up with a newer 4.x version
)that should have solved the problems of transatlantic
)links, while maintaining good interactive speed, but
)sofar I haven't seen any sign of that new release.

Not entirely true, too...



)From: piet@cwi.nl (Piet Beertema):
)	Watching the lights, it *looks* like there are 7 exchanges then
)	a significant (1-3 seconds) pause before communications continues.
)	Has anyone seen similar performance
)Yes.
)	and fixed the problem ?
)yes: go back to 3.0 software level.
)
)	Both telebits are using version 4.00 ROMs
)The problem is in 4.0; and you can *hear* it going wrong:
)first give "atm2" to constantly enable the speaker, then
)set up the connection by hand. And then listen to the
)endless retrains/renegotiates of the modems trying to get
)"in sync" again; those are the pauses you observe.
)

Don't go back to 3.0 software-level...



Well, all those replies were correct, I noticed exactly the same 
strange retrains/renegotiations.

But then I set the register: S120=12
(Don't complain, please... I don't have any description of register 120..
I didn't even know, there was a register 120 before...,
AT&W doesn't save register 120, so include it into your dialer-script, 
I've got that information from Rick Adams, ...)

And guess, what happened: The modem transferred text files across the
ocean at a rate of > 1700 chars/sec, without retrains/renegotiations etc..

Hope, you can share my good experience..

Hans
-- 
Hans Korneder                            SNAILMAIL: Altos Computer Systems
UUCP: korn@altger.uucp                              Wuermstrasse 55
BANG: ...!uunet!mcvax!unido!altger!korn             D-8032 Graefelfing (Germany)