Basic OSPF configuration on Cisco routers

When enabling OSPF on the loopback interfaces of RT1 and RT2, you can simply put their network addresses instead of their IPv4 addresses:

RT1: 172.16.0.0 0.0.0.255 area 0

RT2: 172.31.0.0 255.255.255.0 area 0

source

cisco academie