pppd problem -- modem *not* disconnecting when connection lost.

[Rob Browning <osiris@cs.utexas.edu>]

I've had a problem with my modem, ppp, and detecting disconnections
for quite some time now, and I have been completely unable to resolve
the problem.  I thought I'd bring it up now in case anyone had fresh
ideas.  Feel free to direct me to a more appropriate location if
warranted.

Basically the problem is that I can run pppd to connect to my ISP with
no problems, but then pppd will never die, even if the connection to
the other machine is lost.  I can pick up the line and hear a dial
tone, but pppd will still think it's connected.  I assume it's some
kind of handshaking problem, but I could have sworn I had all that set
right.

I have a USR 28.8 Sportster Internal (I've checked the ROM revision
date), and I'm using it to connect via ppp.  My ppp-options are as
follows:

connect /etc/ppp/ppp-connect
/dev/cua0
38400
crtscts
modem
defaultroute   

I've experimented with a number of modem string settings, and none of
them seem to help.  Right now I'm just using the ones that the USR
manual recommends for hardware handshaking, augmented by the USR tip
from the Linux Serial-HOWTO.  My ppp-connect script (aside from
variable assignments) is as follows:

#! /bin/sh
/usr/sbin/chat ABORT BUSY ABORT 'NO CARRIER' \
  ''   'ATZ' \
  'OK' 'AT&F1' \
  'OK' 'AT&H1' \
  'OK' 'AT&R2' \
  'OK' 'AT&B1' \
  'OK' 'AT&D2' \
  'OK' 'ATS13=1' \
  'OK' 'ATM1L3' \
  'OK' 'ATX4' \
  'OK' "ATDT$phone" \
  CONNECT '' \
  name: $login \
  word: "$password" \
  '>' 'ppp default'             

These commands are used to initialize the port at boot time:

STD_FLAGS="session_lockout"
SETSERIAL=/bin/setserial 
${SETSERIAL} -b  /dev/cua0 uart 16550A port 0x3F8 irq 2 spd_vhi ${STD_FLAGS}

and these (are they necessary?) hopefully finish setting up the port.

/bin/stty -ixon -ixoff -clocal crtscts < /dev/cua0

Thanks for any help.
--
Rob