I have an origin/edge deployment in a datacenter that provides public and private IP's on separate NIC's. What I'd like to do is have my edges make their repeater connections to the origin over the private IP, as I don't pay for bandwidth on the private IP.
I'll still need to bind the origin to a public IP to accept encoder connections, and I'll need to bind the edges to public IP's to accept player connections.
Charlie suggested you look for an option outside of Wowza Server. There might be a way to use IP tables to control routing. You should be able to control which NIC card traffic flows over based on IP address.