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OSPF OSPF Packet Types Type Name Purpose 1 Hello Neighbor discovery, DR/BDR election, keepalive 2 DBD LSDB table of contents exchange 3 LSR Request specific missing LSAs 4 LSU Delivers actual LSAs 5 LSAck Confirms LSU receipt LSA Types Type Name Originated By Scope Blocked By 1 Router Every router Area — 2 Network DR Area — 3 Summary ABR Domain Totally Stubby, Totally NSSA 4 ASBR Summary ABR Domain Totally Stubby, Totally NSSA, NSSA, Stub 5 AS-External ASBR Domain All stub and NSSA areas 7 NSSA External ASBR (NSSA) NSSA only — (translated to Type 5 at ABR) Area Types Area Type 3 Type 4 Type 5 Type 7 Default Route Standard Yes Yes Yes No No Backbone Yes Yes Yes No No Stub Yes No No No Yes (auto) Totally Stubby No No No No Yes (auto) NSSA Yes No No Yes No (configurable) Totally NSSA No No No Yes Yes (auto) Adjacency States Down → Init → 2-Way → ExStart → Exchange → Loading → Full ...