well, this is the scenary for my NOC
i have 2 mt, each on them have 3 ethernet, 2 bridged for give public IP's, the another NIC is for rip.
The bridge is on arp-proxy, the rip interface have 17.16.15.x ip (private), customers don't have rip on the network.
My reason for use rip is make the traffic from MT A go to MT B with the RIP interface not for internet, do you understand me?
The ip duplicated is the is of my customers (they connect with mt box with pppoe).