R1#sh run | b ospf
router ospf 1
 router-id 1.1.1.1
 log-adjacency-changes
 network 17.57.100.1 0.0.0.0 area 0
!


R3#sh run | b ospf
router ospf 1
 router-id 3.3.3.3
 log-adjacency-changes
 network 17.80.1.1 0.0.0.0 area 0
!

R4#sh run | b ospf
router ospf 1
 router-id 4.4.4.4
 log-adjacency-changes
 network 17.80.1.2 0.0.0.0 area 0
!

S6#sh run | b ospf
router ospf 1
 router-id 6.6.6.6
 log-adjacency-changes
 network 17.57.100.2 0.0.0.0 area 0
!