OSPF is a link-state routing protocol。It is designed to be run internal to a single __(71)__system。Each OSPF router maintains an identical __(72)__ describing the autonomous system’s topology。From this database,a routing table is calculated by constructing a shortest-path __(73)__。OSPF recalculates routes quickly in the face of topological changes,utilizing a minimum of routing __(74)__ 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__(75)__。 71