LinuxSA Mailing list archives

  From: Toby Corkindale <tjcorkin@steadycom.com.au>
  To  : Darryl Ross <darryl@bachblue.com.au>
  Date: Wed, 03 Mar 1999 23:36:33 +0000

Re: Modem Problems

Heyas,
I've got a new twist on this subject.
I was trying to install a modem in a linux box for a friend.
First of all we were trying with a 486dx-33, which just plain would not
recognize the modem.
Well, it would recognize that a UART was present (since it was an
internal modem), and the IRQ could be configured (com3, irq 5), but no
data could be passed to or from the modem.
I gave up and transfer the harddrive with linux into a different
486dx-33 (although very similar), and the modem worked first try. 

However, we then got exactly the same problem as some of you have been
describing - it would sometimes pause and buffer packets for a long
time. Only, where you are finding about 8 seconds, this one would get to
40-50 seconds!
It was an internal 33.6 KTX modem (not my modem!), but apparently it
"used to work fine" in a different windows-installed 486.

I agree that the problem seems to be retraining-related, and I vaguely
recall having some problem with my 28.8 when I bought it years ago. At
the time I think I solved it by adjusting the fallforward/back
parameters. Some modems I connected to wouldn't try and retrain when my
modem demanded it. Thus, I disabled retraining altogether for a while. 
This was in my days of BBSing, when my modem had to talk to all kinds of
wierd & wonderful other modems, and now that I'm internet based and only
really talking to 1 type of modem, I've reset it back since.
However, I reccommend giving that a try (see your manual for details,
they vary). 
Oh, and if anyone's got an internal ktx 33.6 (or 28.8) and they've got a
manual for it, could you pass on the relevant commands to me too?
Thanks,
Toby

Darryl Ross wrote:
> 
> >Alan Kennington wrote:
> >
> >> Rick,
> >>
> >> I agree that noise could be triggering the modem problems,
> >> but it's unlikely to be the reason it stays around.
> >>
> >> The nature of the problem is that the line is perfect for
> >> about 2 to 30 days, and then it goes wrong until the modem is
> >> reset. I kept it in the pathological state for
> >> about 8 hours last time, logging every single packet.
> >> And when I re-start pppd, the problem goes away for
> >> many more days.
> >>
> >> It's unlikely that the noise would just stop when I
> >> restart pppd.
> >
> >Correct (trivially) but i fthe modem has tracked down to a slow baud
> >rate to cope with the line then resetting will provide a magic fix.
> 
> So, the modem is slowing down when there is noise on the line, but not
> realising that the noise has gone away, and so not speeding up again?
> Reading through the manual for the modem, there is a swtich to "enable line
> quality monitor and fallback/fall forward". If this is the problem, setting
> this option would solve the problem? The option is %E2, so I need to at that
> to my initialisation string?
> 
> Cheers
> Dazz
> 
> --
> 
> All of Life's mysteries are on your TV
> # 37. When they are alone, all foreigners prefer to speak English to each
> other.
> 
> --
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-- 
...Veni, Vidi, VC++. (I came, I saw, I kludged)

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