(第2空)OSPF is a link-state routing protocol. It is designed to be run internal to a single ( ) system. Each OSPF router maintains an identical ( ) describing the autonomous system's topology. From this database, a routing table is calculated by constructing a shortest-path ( ) . OSPF recalculates routes quickly in the face of topological changes, utilizing a minimum of routing ( ) traffic. OSPF provides support for equal-cost multipath. An area routing capability is provided, enabling an additional level of routing protection and a reduction in routing protocol ( )