Monday, 19 March 2012

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

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)

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.

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