Hello,
When OSPF finds out it runs over a NBMA network - which is your case - it always expects you to configure directly reachable neighbors explicitly in addition to using the network command. Your current OSPF configuration on R1 and R2 is missing the neighbor commands necessary to accomplish this task. Therefore, please add the following commands:
On R1:
router ospf 1
neighbor 192.168.1.2
neighbor 192.168.1.3
On R2:
router ospf 1
neighbor 192.168.1.1
On R3:
router ospf 1
neighbor 192.168.1.1
Also, because in NBMA networks, the spoke routers must not be allowed to join the DR/BDR elections, you must configure them with priority of 0, so:
On both R2 and R3:
interface Serial X/Y
ip ospf priority 0
Lastly, OSPF will assume here that each router in this network can reach each other directly. This is not true in a hub-and-spoke network, as the spokes have no VCs to each other. This will cause that while all routing tables will be correctly populated, R2 won't be able to reach networks behind R3 and vice versa because both routers will assume they can talk to each other directly which they can't. As for now, I am not going to post a solution because I want you to give it a good thought and try to come up with solutions. I will be glad to help after seeing your suggestions
Best regards,
Peter
