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Re: PON dials out, but PPP connection dropped



David Karlin <funk48@travelin.com> writes:

> Hello,
> I've been messing around with Debian/Linux for about 3 months now.  I
> recently acquired a modem for my hamm box and am trying to set up my
> system for a ppp/pap connection.
> 
> I have run pppconfig, and now when I do "pon", the system waits about
> 1/2 minute, and dials the ISP's number.  After the modem dials the
> number, I can hear the carrier-detect; then the modem disconnects in
> about another 1/2 minute.  The same thing happens (more or less) when
> I run minicom.
> 
> I have attached some of some related files.  Also, this computer is on
> a LAN (in case that makes any difference).
> 
> I got some help today (in IRC) from someone who works at an ISP that
> runs Debian, and he was stumped.  If anyone can figure this out, I will 
> owe you a beer (or six).
> 
> TIA,
> 
> --David

The wait between the "pon" command and the modem dialing is telling -
that wait shouldn't be happening.  I'd suspect an IRQ problem - that
is, your modem is set to use the wrong IRQ.  When this happens, data
comes back from the modem only very slowly; this means that there's a
long wait for the "OK" in the second line of the chatscript, which
explains the initial delay in dialing.  This also interferes with data 
coming back from your provider in a timely fashion, which is leading
pppd to think that a timeout occured in getting config. information,
and so it hangs up.

Can you use your modem through minicom?  If so, is it ungodly slow?
That's a better sign that there's an IRQ problem.

To fix this, you need to find out what IRQ the physical modem is using 
(check the modem manual to find this out; if it's an external modem
check your BIOS - should be IRQ 3 or 4, but some bioses let you set
the IRQ on serial ports to 12).  Then, you need to set the modem
device to use this irq:
setserial /dev/ttyS1 irq ??

(where for ?? use what you found; instead of ttyS1 use what's
appropriate for your system)  If this works, modify the file
/etc/rc.boot/0setserial to make this irq change permanent.


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