OSPF area types
Types of OSPF routing devices
As shown in the figure, OSPF uses the following types of routing devices:
Internal Router (IR)—a router that has all of its interfaces within the same area. IRs maintain LSDBs
identical to those of other routing devices within the local area.
Area Border Router (ABR)—a router that has interfaces in multiple areas. ABRs maintain one LSDB
for each connected area and disseminate routing information between areas.
Autonomous System Boundary Router (ASBR)—a router that acts as a gateway between the OSPF
domain and non-OSPF domains, such as RIP, BGP, and static routes.
OSPF domain and an autonomous system