What are different area types used in the OSPF?

ospf area types

ospf area types

 

Area Types
-Standard area
-Backbone area (area 0)
-Stub area
-Totally stubby area
-Not-so-stubby area (NSSA)
-Totally NSSA
Stub Area (area stub)
-It contain type 1, 2, and 3 LSAs
-No LSA type 4 and 5 (E1 or E2) is allowed
-Routers can connect to the External routes via the default route that is injected by the ABR
-It can’t have an ASBR
-The Backbone area can’t be configured as a Stub area

Totally Stub Area (area <area>stub no-summary)
-Cisco proprietary
-It contain type 1, 2 LSAs
-LSA Type 3, 4 and 5 are stopped
-A default route is injected by the ABR.
-Only ABR has to be configured with the “no-summary” command
-Intra area routers in the Totally Stubby area should have “area <area> stub” command

  • Standard areas can contain LSAs of type 1, 2, 3, 4, and 5, and may contain an ASBR. The backbone is considered a standard area.
  •  Stub areas can contain type 1, 2, and 3 LSAs. A default route is substituted for external routes.
  • Totally stubby areas can only contain type 1 and 2 LSAs, and a single type 3 LSA. The type 3 LSA describes a default route, substituted for all external and inter-area routes.
  •  Not-so-stubby areas implement stub or totally stubby functionality yet contain an ASBR. Type 7 LSAs generated by the ASBR are converted to type 5 by ABRs to be flooded to the rest of the OSPF domain.