OSPF Neighbor Relationships

5 Requirements for OSPF to form a relationship with a neighbor:

1. Hello and Dead timers must match

2. Network mask must match

3. Area ID must match

4. Authentication password must match (if you are using OSPF authentication)

5. Stub Area Flag must match

Also found a great wiki on OSPF best practices: http://wiki.nil.com/OSPF_area_configuration_best_practices