• A not-so-stubby area (NSSA) can import AS external route information and send it to the backbone. It cannot receive external ASinformation from the backbone or other areas.• Totally stubby areas are referred to as no summary areas in the Dell Networking OS.Networks and NeighborsAs a link-state protocol, OSPF sends routing information to other OSPF routers concerning the state of the links between them. The state(up or down) of those links is important.Routers that share a link become neighbors on that segment. OSPF uses the Hello protocol as a neighbor discovery and keep alivemechanism. After two routers are neighbors, they may proceed to exchange and synchronize their databases, which creates an adjacency.Router TypesRouter types are attributes of the OSPF process.A given physical router may be a part of one or more OSPF processes. For example, a router connected to more than one area, receivingrouting from a border gateway protocol (BGP) process connected to another AS acts as both an area border router and an autonomoussystem router.Each router has a unique ID, written in decimal format (A.B.C.D). You do not have to associate the router ID with a valid IP address.However, to make troubleshooting easier, Dell Networking recommends that the router ID and the router’s IP address reflect each other.The following example shows different router designations.Open Shortest Path First (OSPFv2 and OSPFv3) 573
