LinuxSA Mailing list archives

  From: Alan Kennington <akenning@dog.topology.org>
  To  : rjm@herzfeld.com.au
  Date: Thu, 4 Mar 1999 00:09:48 +1030

Re: Modem Problems

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. Also, the link from the cisco router to me
is digital except for the last leg to my house.
I.e. the next time I dial, only the digital lines
are different, not the analogue stretch, which is the only
bit that could reasonably have noise.

It just might be that there are 33.6 k modems out there that
do not have matching state machines, in which case
the sync seeking algorithm may be faulty in some way.

Strangely, the problem has tended to happen after I ahve been
passing a lot of traffic onthe link.
Last time it was when the yahoo robot or spider was browsing my
site at the same time at the googlebot
(http://www.google.com).
this seems to indicate that there could be some
buffer overflow condition which triggers the
modem on one side to go into an unusual state from which it
cannot extricate itself.

The telstra engineer told me if I turned off
compression, it shoudl be fine.
But I turned off compression (%c0 or somehting), and
I still get 5 kBytes/sec on a 33.6 kbit/sec modem,
which is impossible.
I just wonder if MS windOS users get this problem too,
or if maybe their machines never stay up long enough
to see the problem.

Maybe I should put the problem to a different e-mail list.
Does anyone know of a newsgroup or something where
the world's modem experts congregate?

Regards,
Alan Kennington.

-- 
Check out the LinuxSA web pages at http://www.linuxsa.org.au/
To unsubscribe from the LinuxSA list:
  mail linuxsa-request@linuxsa.org.au with "unsubscribe" as the subject