We use linux computer as our office gateway. It has two Internet connection and one LAN connection. My problem is that whenever there is any gateway software configuration problem or hardware problem, LAN clients looses internet connection. To solve this, I was thinking to create a cluster of two gateway PCs running same services(proxy,firewall,IDs etc) so that any one of them has problem, traffic can reach internet through the other gateway. I assume clustering gives single IP to all nodes in cluster so all LAN client will have cluster IP as their gateway. I would like to know any open source or free software which can do this on linux or if there is any better way of achieving the same.
Thanks in advance! Sanket