The OSPF on cisco router can operate in various mode over NBMA network. the choice of mode available depend on the topology of the NMBA network. Each of the mode has unique configuration requirement in the ospf network. Network type of NMBA networ...
http://www.ebrahma.com/2013/10/nbma-topology-modes-of-operation-in-ospf/Labels: Broadcast, DR-or-BDR-election, Modes, NBMA, non-broadcast, of, Operation, point-to-multipoint, point-to-multipoint-nonbroadcast, Point-to-Point, Topology