how do i tell my SuSEFirewall to separate the traffic for the 3 links

This is usually not the job of Susefirewall, since it does not support source based routing. Check out "iproute2" to send outbound traffic over multiple links. An in depth howto is the "Linux Advanced Routing & Traffic Control" [1][2] polarizer's 2 cent [1] http://lartc.org/ [2] http://lartc.org/howto/lartc.iproute2.html