OSPF Network Type Non-Broadcast

Lessons Discussion
5

The topology is simply three routers R1, R2 and R3 connected to a switch in a multic-access segment.
R1 has:

interface FastEthernet0/0
ip address 123.1.1.1 255.255.255.0
ip ospf network non-broadcast
duplex half
!
router ospf 1
router-id 1.1.1.1
network 1.1.1.0 0.0.0.255 area 0
network 123.1.1.0 0.0.0.255 area 0
neighbor 123.1.1.3
neighbor 123.1.1.2

R2 has:

interface FastEthernet0/0
ip address 123.1.1.2 255.255.255.0
ip ospf network non-broadcast
duplex half
!
router ospf 1
router-id 2.2.2.2
network 2.2.2.0 0.0.0.255 area 0
network 123.1.1.0 0.0.0.255 area 0
neighbor 123.1.1.3
neighbor 123.1.1.1

and R3 has:

interface FastEthernet0/0
ip address 123.1.1.3 255.255.255.0
ip ospf network non-broadcast
duplex half
!
router ospf 1
network 3.3.3.0 0.0.0.255 area 0
network 123.1.1.0 0.0.0.255 area 0
neighbor 123.1.1.1
neighbor 123.1.1.2