I know that this has been ask a lot but I don’t see any specific instructions on how to do it.

Right now I have 2 ISP with eth1 and eth2. 1 Local interface eth0 is also setup. Whenever an ISP loses its internet connectivity, what we do is manually reroute it to the other ISP using yast lan. What i want now is have it automatically switch whenever the isp being used is down and switch it to the backup. Does anyone here knows how?

VERSION=“12.3 (Dartmouth)”
PRETTY_NAME=“openSUSE 12.3 (Dartmouth) (x86_64)”

To do this <properly> requires some expertise.
Over the years, I’ve always pointed anyone asking this question to

The alternative is to spend about $100 US(Last I checked which was over a decade ago) and buy a special NIC that will do it automatically for you.

If you have time on your hands(like I when I was a beginning Admin and the company I was working for allowed me to pretty much experiment with whatever I wanted to, as long as the company was fully supported and running without problems), then you can see for yourself the results configuring things like gateway priorities (you’ll be disappointed) and various round robin configurations.