Reboot network cards on Network Lost

network_chek.sh

#! /bin/bash
#(c)2011-2012 Jesus Christian Cruz Acono JesusChristian (At) Tequilavalley.com
#constant check network connectivity, on lost
#re-start Cards if lost are "more large" 
#reboot the system.
#the script check connectivity by ping to "arbitrary IP"
######config zone######
#IP to make the ping to check, in this moment uses GOOGLE IP (google cant negate the ping)
#you can use a "domain name" to "aditional" check de dns resolv
PINGIP="64.233.169.103"
#interfaces to check (eth. wlan etc)
ETHS="eth0 eth1 eth2 eth3"
#ifdonw comand
IFDOWN="/sbin/ifdown"
#if up comand
IFUP="/sbin/ifup"
#action comand
REBOOT="/sbin/reboot"
#default wait time
SLEEPTIME=45
#defaul initial status
CONNECTION=1
####execution zone, no config########
for (( ; ; )) do
        if ping -c 1 $PINGIP > /dev/null;then
                CONNECTION=0
        else
                if [ $CONNECTION = 0 ]; then
                        CONNECTION=1
                        for ETH in $ETHS
                        do
                           $IFDOWN $ETH
                           $IFUP $ETH
                        done
                fi
                if [ $CONNECTION = 1 ]; then
                        $REBOOT
                fi
        fi
        sleep $SLEEPTIME
done