Nonprimary interface as default route

[gshenaut]

I need to use LAN-internal addresses is setting up OD master and replica, because I do not want replication traffic to go over the Internet. Here is a sketch of the network:

What I want to do is to make interfaces Ya & Yb the primary interfaces of both servers, but manually set up their default routes on interfaces Xa & Xb. I already have each subnet routed to each other through Za & Zb. Note that the two servers are located at different sites. I’m hoping that the default routes can be set up in /etc/rc.local, where I set up the routes for interfaces Za & Zb.

I think I have to do something like this to use a secondary interface as the default route, because OSX normally assumes that the primary interface is the default route, and also the OD server. What I think I will get out of this setup is the ability to have the OD domain be based on the Ya address & name, which is internal, and the replica set up on Yb, also internal. These will be accessible only by hosts inside the LAN. I’m hoping that services such as ssh, email, and web authentication will still be available from the outside via Xa & Xb.

I’ll be trying this tomorrow, but I thought I’d see if anyone had a reaction to it as a plan. As I see it, the most critical part will be establishing the new default route on the non-primary interface, everything else should just work.

Greg Shenaut

[gshenaut]

Well, I didn’t have much success. I can change the default route by hand, but establishing it in /etc/rc.local doesn’t stick like it does for other static routes.

I wonder: why there is this insistence on there being a "primary interface" anyway? Why does the interface with the default route also have to be the OD master? They’re just IP addresses, after all. I see no logic in it.

Next I’m going to see if I can set up a nonstandard default route using the launchd system.

Greg Shenaut

[Author]

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