In the case of configuring NBMA, OSPF will only send one Hello package to each router at the same time (HELLO package periodically, used to establish and determine neighbor relationship between routing) instead of multicast . The HELLO package has a range of 10s to 30s during the transmission cycle of the Hello package, and the time range of the neighbor failure (DEAD) is 40 s ~ 120s (4 times the Hello package delivery interval).
NBMA (Non-Broadcast Multiple Access) IS One of Four Network Types in The OSPF (Open Shortest Path First) Communications Protocol. NBMA IS Used To Accurately Model X.25 and frame relay environments in multiple-access networks where there are no intrinsic broadcast and multicast capabilities The other OSPF network types are:.. broadcast, point-to-point, and point-to-multipoint in an NBMA configuration, OSPF sends HELLO packets ( packets sent periodically to establish and confirm neighbor relationships between routers) to each router one at a time rather than multicasting them. The HELLO timer (which tells the router how often to send HELLO packets) is extended from 10 to 30 seconds and the dead router Timer (Which Tells the Router How long (Which Tells The Router How long "is extended from 40 to 120 seconds.
