I get my net connection from Metricom using their "always on" ricochet.net 
service.  From time to time, my ppp network connection disappears.  ifconfig 
says that the interface is up and pppd remains running but no packets come in 
and none go out.

I found a way to keep the ppp connection alive.  I wonder if there is a better 
way.

#!/bin/sh
...
if [ `/sbin/ping -c 1 -q $ISP_NAME_SERVER` -ne 0 ] ; then
  $RESTART_THE_NETWORK
fi