I have a Red Hat linux server X on a x.x.0.0 network. This machine also has to communicate with another server Y on a network called y.y.0.0

Server X has two network interfaces.

eth0 is configured on the x.x.0.0 network and has a default gateway on the x.x.0.0 network.

In order to communicate server Y on the y.y.0.0 network I'm planning on configuring eth1 with a y.y.0.0 IP address and gateway. I then want to add a static route on eth0 that uses eth1's IP address as a gateway.

Example (using fictional IP addresses):

SERVER X -> eth0 192.168.0.1 (add static route 20.10.0.0 gw 20.10.0.1)
-> eth1 20.10.0.1

SERVER Y -> 20.10.0.10

My logic tells me that if I then request to talk to server Y the request will go to eth1 via the static routed on eth0. eth1 is on the same network as server Y, so the request should then be able to reach server Y

Could someone please confirm that his is correct (or incorrect for that matter).

Cheers

If eth0 is on network A and eth1 is on network B, you don't need a static routes to communicate with either of those two networks.

Right, so are you saying the following?

If I have server X with eth0 on network A with and eth1 on network B and I ping the server Z on network B it will go directly to server Z and not to the default gateway of server X.

of course it will. you will still have routes in your routing table for all networks you are directly connected to. it's possible to override them if you want to really screw things up, but by default there's nothing at all interesting or complex about what you're asking. you just have two nic's on two networks. there is no primary or secondary interface or anything notional like that.

Yes, the action of configuring an interface automatically adds a route for its directly-connected network. Furthermore, that route is the only piece of information needed to communicate with a machine on that network; i.e. gateways are irrelevant.