Hi,

1.On point-to-point links such as High-Level Data Link Control (HDLC) and Point-to-Point Protocol (PPP), Open Shortest Path First (OSPF) runs as a point-to-point network type. This network type is enabled by default.

2.In order to check the network type of an interface that runs OSPF, issue the show ip ospf interface command.

3.Before OSPF runs on the network, it has to discover the neighbor

4.In a point-to-point topology, neighbors are discovered automatically since neighbors are directly connected to each other through a point-to-point link, and broadcast or multicast packets are forwarded over the network; however, the DR and BDR election does not take place as explained earlier

5.n an NBMA network topology like Frame Relay , which is inherently nonbroadcast, neighbors are not discovered automatically.

6.Neighbors must be configured manually to overcome these problems

7.There are two ways to simulate a broadcast model on an NBMA network: define the network type as broadcast with the ip ospf network broadcast interface sub-command or configure the neighbor statements using the neighbor command under router ospf command.

configure neighbor command on both sides.

HTH..rate if helpful..