i have 2 fedora core 5 box with 2 link from the ISP
the frist box is a gateway for a local client (10.0.0.100 - 10.0.0.200) and the second box is a gateway for another local client ( 10.0.0.210 - 10.0.0.244 )

i want if the frist gateway is down then the clients will be automaticlly switching to the second gateway and Vise Versa without to change thier gateway manually