OSPF LSA Types:
Type 1 LSA: Router LSA:
Router LSAs are generated by every router. The router LSA is a list of links attached to the router, as well as the state of the link and the outgoing OSPF cost associated with the link.
#Show ip ospf database router
Type 2 LSA: Network LSA:
Network LSAs are generated by the DR on a multi-access segment.
# show ip ospf database network
Type 3 LSA: Network Summary LSA:
Network summary LSAs are generated by ABRs.
# show ip ospf database summary
Type 4 LSA: ASBR Summary LSA:
ASBR summary LSAs are also generated by the ABR. This LSA describes the location of an ASBR and the cost to reach it.
# show ip ospf database asbr-summary
Type 5 LSA: External LSA:
AS LSAs are originated by the ASBRs and describe a network outside of the AS.
Scope: Entire OSPF Domain
# show ip ospf database external
Type 7 LSA: NSSA LSA:
NSSA LSAs are originated by the ASBR within the NSSA.
LSA Type 7 gets converted to LSA Type-5 when going out of NSSA area by ABR.
Scope: NSSA Area
#show ip ospf database nssa-external