Current expectations from all type of systems and services is to be available without any disruption. One of mission critical systems is gateway/firewall. Of course you can use multiple products available on the market. One of them is openSUSE, which is perfect to act as gateway/firewall between Internet and production systems. So, how to provide redundancy for openSUSE and same time be able to keep it up-to-date without any disruption for production systems?
openSUSE 13.2 with keepalived provides all technology required to make your firewall high-available.
Here is diagram of Lab created to configure and test openSUSE with keepalived: