OSPF Network Types

This table summaries which OPSF network types are available.

OSPF Network Type	Hello / Duration	DR/BDR Election	Next hop LSA modified?	End pts advertised?	Proprietary?
Broadcast	Multicast / 10sec	Yes	No	No	Cisco
Non Broadcast (NBMA)	Unicast / 30sec	Yes	No	No	RFC2328
Point-to-Multipoint (Broadcast)	Multicast / 30sec	No	Yes (set to neighbour)	Yes (as /32s)	RFC2328
Point-to-Multipoint (Non Broadcast)	Unicast / 30sec	No	Yes	Yes (as /32s)	Cisco
Point-to-Point	Multicast / 30sec	No	No	No	Cisco

• If the Hello's are unicasted then no "broadcast" keyword is required in the frame-relay map command. However you will need to add the neighbour statements.
• If the Hello's are multicasted then the "broadcast" keyword is required in the frame relay map command.

• default frame relay OSPF interface type is: Non Broadcast
• default ethernet OSPF interface type is: Broadcast 
• default serial OSPF interface type is: Point-to-Point

• If the Next hop LSA has been modified it means for one leaf node (ie spoke) to get to another the next hop is set to the hub router. In the unmodified case the next hop is set to the leaf note and the correct frame relay map is installed.