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

Wed Feb 1 19:35:27 UTC 2012
Steve Clark <sclark at netwolves.com>

On 02/01/2012 02:03 PM, Nick wrote:
> 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 on subnet gateway
>   - eth1 with on subnet gateway
> 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 dev eth1 weight 1 \
>     nexthop via 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)?

I just tried this and besides needing ip route "add" default

It does not seem to work when I unplug the cable on my primary link.

Stephen Clark
Director of Technology
Phone: 813-579-3200
Fax: 813-882-0209
Email: steve.clark at netwolves.com