How to configure OSPF neighborship only with the known neighbor's IP address

This article explains how to configure multiple neighbors for establishing OSPF peering.

OSPF routers normally discover their neighbors dynamically by listening to the Broadcast or Multicast Hello packets on the network. Because an NBMA network does not support Broadcast (or Multicast), the router cannot discover its neighbors dynamically, so you must configure all the neighbors statically. Do this by including the neighbor statement and specifying the IP address of each neighboring router in the address option.

To configure multiple neighbors, include a neighbor statement for each neighbor. This is also known as NBMA network. All routers must have a direct connection to both the designated and backup designated routers, or unpredictable results occur.  If the neighbor is allowed to become the designated router, include the eligible keyword.

In order to send unicast hello message of OSPF neighborship, the following can be configured:

[edit protocols ospf area 0]
 interface interface-name { 
         interface-type nbma; 
         neighbor [IP address ] <eligible>;  ->Eligible Neighbour
         poll-interval seconds; 
 }