Here is a sample net diagram-
R3 (s1/0) - R5 (s1/0) - R4 (s1/0)
----------- R5 (e0/1) - R4 (e0/0)
I have Frame Relay running using the serial connections in R3, R5, and R4 and OSPF is enabled with AS 0.
I also have a Ethernet connection between R4 and R5 that configured with OSPF AS 45.
OSPF is working just fine thru the serial connections on top of Frame Relay. For the Ethernet connections I am using OSPF Non-broadcast and only works when I specify from R4 "neighbor (R5's e0/1 ip address) (that I found in a sample configuration). My question is what is the purpose of the Neighbor command in OSPF?