FAILOVER - 2 Links - 1 Server (Redundant Internet)

[IgorOV]

Hi all!

After reading lots of forums I decided to create my own script to do that.

It has done the job for some hour, but dont know why after 5, 6 or a bit more hours the internet simply stops

The ideia is:
2 Links
one via DHCP(Cable modem) (eth2) (Dynamic IP)
one via PPPOE(Fiber modem) (eth1/ppp0) (Static IP)

When linux boots up automatically starts with eth2 working as I do not run the command: pon dsl-provider

Alright, so far, the fiber modem keeps in standby.

My script runs ping command and when it returns (0) it means the internet is OK, it sleeps for 25 seconds and then tests again.

Any other result the script runs the following:

ifdown eth2
pon dsl-provider

which means the DHCP Cable Modem (Dynamic IP) is disable and the Fiber modem (Static IP) is enable

After that the script loops itself and runs ping tests again.

Once it gets a result other than 0, it runs:

poff -a
ifup eth2

Which means, disconnect PPPOE and enable eth2 through DHCP

I will print my script below

Does any one see any problem with it?

[IgorOV]

### SCRIPT BEGIN
INTERNET="LINK1"

while : ; do

ping -c 1 200.154.56.80

if [ $? -eq 0 ]; then
echo INTERNET OK
else

if [ $INTERNET = "LINK1" ]; then
echo SWITCHING OFF, LINK1 - SWITCHING ON, LINK2
INTERNET="LINK2"
ifdown eth2
sleep 1
pon dsl-provider
ddclient
/etc/init.d/squid restart
else
echo SWITCHING OFF, LINK2 - SWITCHING ON, LINK1
INTERNET="LINK1"
poff -a
sleep 1
ifup eth2
ddclient
sleep 1
/etc/init.d/squid restart
fi
fi

sleep 25
done
### SCRIPT END


it is run in the /etc/network/interfaces file as below:

pre-up /bin/script &


I also have the MASQUERADE line for ppp0 and eth2

[IgorOV]

When I unplug the coaxial cable from the modem, the script switches the link correctly and stays there until I unplug the fiber cable from the fibermodem. (after having put back the coaxial cable in the other modem)

Assuming that the 2 links are DOWN, the script will switch link1 and link2 until one of them comes online again.

BUT if the one in use is OK, it should not be switched to other link, right?

Well,,,.. Does any one see any mistake I may have made?