Frank Murphy (Frankly3d) píše v St 03. 06. 2009 v 08:00 +0100:
Is Fedora as Server, able to do what is described in the
answer to my Q? on the Irish Linux User Group link  Background 
"It occurs to me that a linux box with equal-cost multipath support
might be able to "do the right thing" with two separate POSTROUTING
entries and the appropriate double default route, but I've never built
this and would need to test it in a lab carefully."
I was using a setup multiple providers on a router/firewall with
Shorewall (version 3.x) as the high level configuration tool for
iptables. See the docs for the "providers" config file in Shorewall.