In OSPF, what is the term for a router connecting multiple areas?

In OSPF (Open Shortest Path First), the term used for a router that connects multiple areas is the Area Border Router (ABR). An ABR is responsible for managing the boundary between different OSPF areas. It maintains separate link-state databases for each area it connects to, which allows for efficient routing and minimizes the amount of routing information that needs to be shared.

The primary function of an ABR is to ensure the smooth communication and routing of data between the different areas of an OSPF network while preserving the hierarchical structure of OSPF. This role is critical for scaling OSPF in larger networks, as it helps to limit the size of the OSPF routing table and reduces the amount of flooding that occurs within individual areas.

Other terms, such as a Border Router, refer to routers that connect OSPF networks to external networks, but they do not specifically denote routers that interface between OSPF areas. Similarly, Designated Routers serve a different purpose in OSPF by acting as a central point for exchanging routing information within broadcast networks, rather than connecting multiple areas.