[CentOS] ip route and nexthop: the "CentOS" way

Wed Feb 1 19:03:11 UTC 2012
Nick <oinksocket at letterboxes.org>

Hi,

I'm wanting to configure a CentOS 6 server to have a fall-back default route via
a second network interface.

Given:

 - eth0 with 192.168.0.10 on subnet 192.168.0.0/24 gateway 192.168.0.1
 - eth1 with 192.168.1.10 on subnet 192.168.1.0/24 gateway 192.168.1.1

Where eth0's network is a "back door" to the internet, and eth1's is the "front
door", I believe I can configure the routing table manually like this:

 ip route default scope global \
   nexthop via 192.168.1.1 dev eth1 weight 1 \
   nexthop via 192.168.0.1 dev eth0 weight 2

However, I've re-read the RHEL6 documents for configuring static routes here:


http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/s1-networkscripts-static-routes.html

This kind of thing doesn't seem to fit into the scheme of
/etc/sysconfig/network-scripts/route-eth? described there, since the route isn't
"for" any single interface.  Is there a "RHEL/CentOS" way to do this, or do I
need to resort to some sort of script containing the above ip route command
inserted somewhere?

And how do I stop CentOS from trying to pick its own default gateway settings
(since /etc/sysconfig/network likely won't have a GATEWAY parameter)?


Cheers,

Nick

ps. Hints about this obtained from

http://lkml.indiana.edu/hypermail/linux/net/0201.0/0000.html
http://lartc.org/lartc.html#AEN298