When routing with the OSPF protocol, there are different routers
with dedicated functions. The Designated
Router(DR), the Area Border Router (ABR) and the Autonomous System
Boundary Router (ASBR). The Area Border Router (ABR) is a router that connects one or more OSPF areas, Open Shortest Path First, with the backbone network. An ABR router has at least one interface in a routing area and one to the backbone network. ABR routers perform routing interface functions between a specific area and the backbone area.