initial configuration: Cisco Equipment Convenient startup-config
sudo ip addr add 172.16.2.12/24 dev eth0
/sys/module/kernel/parameters/consoleblank
auto eth0 iface eth0 inet static address 172.16.2.11 netmask 255.255.255.0 #gateway 172.16.2.1 #dns-nameservers 172.16.2.250
Above topology Minimum IP Configurations. There is no routing protocol configuration.
en conf t int fa0/0 ip addr 172.16.2.1 255.255.255.0 no shut int fa0/1 ip addr 172.16.1.1 255.255.255.0 no shut end
en conf t int fa0/0 ip addr 172.16.2.2 255.255.255.0 no shut int fa0/1 ip addr 172.16.3.2 255.255.255.0 no shut end
On all routers you need networking verifications.
en conf t router ospf 1 network 172.16.0.0 0.0.255.255 area 0 end