[TriLUG] Conflicting Default Gateways

[Aaron S. Joyner]

Brian Henning wrote:

>Hi List,
>  Ok, I think I have a foggy idea of why this is the case, but I would
>greatly appreciate some tips on how to get around it:
>
>I've got a server with two NICs which are on different subnets (for
>argument's sake, we'll say eth0 is on 192.168.50.0/24 and eth1 is on
>192.168.100.0/24).  Both subnets have their own internet gateways; .50 has
>1.5Mbit DSL service, and .100 has some sort of cable-based service.  Right
>now, eth0 is configured to its subnet's default gateway (.50.1), and eth1 is
>configured with no default gateway.  In this configuration, things work
>normally.  However, if I configure eth1 to be aware of its default gateway
>(.100.1), something becomes amiss, and things such as host and dig get
>broken.  I'm using system-config-network to make these settings; I don't
>know if that matters.
>
You need to look into load balancing these two gateways, or at least 
splitting traffic based on pre-defined parameters.  Check out this 
section of the Linux Advanced Routing and Traffic Control HOWTO:
http://lartc.org/howto/lartc.rpdb.multiple-links.html

I've done this more than a few times, so if you run into a snag feel 
free to post your troubles to the list.

Aaron S. Joyner