BROADCAST, DR/BDR election, auto neighbor, 10s hello.
NON_BROADCAST, DR/BDR election, configured neighbor, 30s hello.
POINT_TO_POINT, no DR/BDR election, auto neighbor, 10s hello.
POINT_TO_MULTIPOINT, no DR/BDR election, configured neighbor, 30s hello.
POINT_TO_MULTIPOINT NON_BROADCAST, no DR/BDR election, configured neighbor, 30s hello.
Avoid mixing of OSPF Network types that works with DR/BDR and those that don't.
On Ethernet segments, use:
BROADCAST (default) , if more than two routers on the segment.
POINT_TO_POINT, if only two routers on the segment.
POINT_TO_MULTIPOINT NON_BROADCAST, usefull to configure neighbor costs, but there should be a full mesh configuration.
On NBMA, use:
NON_BROADCAST (default), use if the mapping is fully configured (static mapping only or dynamic mapping plus static mapping allowed) or at least if all spokes have connectivity with the Hub.
BROADCAST, broadcast must be enabled on each mapping.
POINT_TO_POINT, can be configured on the spokes if the Hub is configured in POINT_TO_MULTIPOINT, but change timers.
POINT_TO_MULTIPOINT, if the mapping is not fully configured (dynamic mapping only) and no BDR are allowed.
POINT_TO_MULTIPOINT NON_BROADCAST, if the mapping is not fully configured (dynamic mapping only or static mapping (to the HUB only or not) but without broadcast keyword) and no BDR are allowed.
On serial links, use:
POINT_TO_POINT (default)
