router ospf 1
network 192.168.12.0 0.0.0.255 area 0
Configuration of Device B:
#Configuring Ethernet interface
interface FastEthernet0/0
ip address 192.168.12.2 255.255.255.0
#Configure the WAN port
interface Serial 1/0
ip address 192.168.23.2 255.255.255.0
#Configuring OSPF routing protocol
router ospf 1
network 192.168.12.0 0.0.0.255 area 0
network 192.168.23.0 0.0.0.255 area 0
Configuration of Device C:
#Configuring Ethernet interface
interface FastEthernet 0/0
ip address 192.168.34.3 255.255.255.0
#Configure the WAN port
interface Serial 1/0
ip address 192.168.23.3 255.255.255.0
Configuring OSPF routing protocol
router ospf 1
network 192.168.23.0 0.0.0.255 area 0
network 192.168.34.0 0.0.0.255 area 34
Configuration of Device D:
#Configuring Ethernet interface
interface FastEthernet 0/0
ip address 192.168.34.4 255.255.255.0
#Configure the ports on the Ethernet card
interface FastEthernet 1/0
ip address 200.200.1.1 255.255.255.0
interface FastEthernet 1/1
ip address 172.200.1.1 255.255.255.0
#Configure the OSPF routing protocol to redistribute the RIP route
router ospf 1
network 192.168.34.0 0.0.0.255 area 34
redistribute rip metric-type 1 subnets tag 34