OSPF routers need to go through several states before establishing a NEIGHBOR relationship:-

1.Down - No Hello packets have been received on the interface.

2.Attempt - In Attempt STATE neighbors must be configured manually. It applies only to nonbroadcast multi-access (NBMA) networks.

3.Init state - Router has received a Hello message from the other OSFP router.

4.2way state - The neighbor has received the Hello message and replied with a Hello message of his own. Bidirectional COMMUNICATION has been established. In Broadcast network DR-BDR election can occur after this point.

5.Exstart state – DR & BDR establish adjacencies with each router in the network. Master-slave election will takes place (Master will send its DBD first).

6.Exchange state – Routing information is exchanged USING DBD (DATABASE Descriptor) packets, Link-State Request (LSR). Link-State Update packets may also be sent.

7.Loading state – LSRs (Link State Requests) are send to neighbors for every network it doesn't know about. The Neighbor replies with the LSUs (Link State Updates) which contain information about requested networks. The requested information have been received, other neighbor goes through the same process

8.Full state - All neighbor routers have the synchronized database and adjacencies has been established.

OSPF routers need to go through several states before establishing a neighbor relationship:-

1.Down - No Hello packets have been received on the interface.

2.Attempt - In Attempt state neighbors must be configured manually. It applies only to nonbroadcast multi-access (NBMA) networks.

3.Init state - Router has received a Hello message from the other OSFP router.

4.2way state - The neighbor has received the Hello message and replied with a Hello message of his own. Bidirectional Communication has been established. In Broadcast network DR-BDR election can occur after this point.

5.Exstart state – DR & BDR establish adjacencies with each router in the network. Master-slave election will takes place (Master will send its DBD first).

6.Exchange state – Routing information is exchanged using DBD (Database Descriptor) packets, Link-State Request (LSR). Link-State Update packets may also be sent.

7.Loading state – LSRs (Link State Requests) are send to neighbors for every network it doesn't know about. The Neighbor replies with the LSUs (Link State Updates) which contain information about requested networks. The requested information have been received, other neighbor goes through the same process

8.Full state - All neighbor routers have the synchronized database and adjacencies has been established.