I read in a book about OSFP that on point-to-point interfaces the routers don't form adjacencies and there is no election of DR nor BDR. Also routers that do not form adjacencies do not send LSAs (routing info) to each other. So my question is how do these routers route if they do not exchange routing info?
On a ethernet segment with multiple routers running OSPF is where you will see this.
I modified the lab so you have 4 routers
R1 = 192.168.10.1
R2 = 192.168.10.2
R3 - 192.168.10.3
R4 = 192.168.10.4
All routers are running OSPF. From the attached screen capture you will see
R4 = DR (Designated Router)
R3 = BDR (Backup Designated Router)
All routers form a full adjacency with these 2 devices. BUt notice that R1 & R2 are in a 2WAY/DROTHER state with each other. They do not exchange LSA's with each other and therefore do not transition to the FULL state.
From lab -
R1 (s1/0 - 192.168.5.1/30) -> P2P -> (192.168.5.2/30 s1/0) R2
See attached screenshot