In this article, we will review “OSPF Over NBMA Network“. First let’s take a look at to NBMA Topology types. There are 3 types of NBMA topologies.
NBMA TOPOLOGIES
* Hub and Spoke (Star topology )
* Partial Mash (Partial redundant topology)
* Full Mesh ( Full redundant topology)
OSPF PROCESS OVER NBMA ( NON-BROADCAST MULTI ACCESS ) NETWORK
There are 5 types of OSPF processes over NBMA networks ;
1) NBMA-RFC Standard
2) Point to Multipoint – RFC Standard
3) Point to point – Cisco
4) Broadcast – Cisco
5) Point to multipoint,non broadcast – Cisco
NBMA MODE:
* Default mode used for x25/Frame Relay/ATM technologies.
* Neighbors must be configured manually.
* Just one subnet must be used.
* Behaves like a Local Area Network.
* DR / BDR selection is made. ( Must have Full Connectivity )
POINT TO MULTIPOINT MODE:
* This mode is so similar to NBMA.
* Fixes the problems that occurs on NBMA.
* Just one subnet must be used.
* No DR / BDR selection is made.( Requests are sent to 224.0.0.5 )
* Neighborship established automatically. ( Since pseudo broadcast is allowed )
POINT TO POINT MODE:
* Different sub-interfaces are used.
* Requires different subnets.
* No DR / BDR selection is made.
* Neighborship established automatically.
