Routable IP ?? Setup.

Hello All

I'm in the process of deploying a 4 node HA Cluster (2 LD, 2 Real Server)
The 2 LDs have 2 nics each   nic 1 on both attached to a switch and nic 2
with a crossover.
The 2 RealServer are attached to the switch also, they have 2 nics also  nic
1(public interface) nic 2 (private, 192.168).

I am looking at the documentation and I am trying to understand where the
real ip comes into play.
I was think I would setup one of my  routable ips as the VIP. So on the
internet the site hosted on this env  would point at the VIP.

If anyone has a minute to shed some light, I would really appreciated it.

Thank You