/etc/interfaces file for multiple gateways, same network? (linux)

Solution 1:

Sure, something like this may work

auto eth0
iface eth0 inet static
    address 10.1.248.11
    netmask 255.255.255.0
    up ip route add default via 10.1.248.1 dev eth0  metric 100 
    up ip route add default via 10.1.248.3 dev eth0  metric 200 

Solution 2:

Yep. Add your ip route add lines to a script called (for example) /usr/local/sbin/routes and then add the following to the interfaces file, alongside the normal directives for eth0:

    up /usr/local/sbin/routes

If you need to, you can add a similar pre-down directive, too, pointing to a different script, or invoking the script with an argument that deletes the routes, instead. (up and pre-down are invoked after the interface is brought up and before it is taken down, repsectively)