OSPF LSA Types: A Field Reference
OSPF link-state advertisements are the currency of the protocol. Understanding which LSA type carries what information — and who generates it — is essential for troubleshooting convergence issues. Quick Reference Type Name Originated By Scope 1 Router LSA Every router Single area 2 Network LSA DR on broadcast segment Single area 3 Summary LSA ABR Area → backbone 4 ASBR Summary ABR Area → backbone 5 AS External ASBR Entire OSPF domain 7 NSSA External ASBR in NSSA Single NSSA area Type 1 — Router LSA Every OSPF router originates one Type 1 LSA per area it belongs to. It describes: ...