OSPF Neighbor Adjacencies !!!

OSPF Neighbor Adjacencies : 

OSPF has to undergo 7 states as follow:

Down:
    When OSPF is configured in One End of R1 or neighbor not yet configured with OSPF, this is where the Down state. Here, the Hello packets will be sent in the Multicast IP Address : 224.0.0.5
Init:
    Once Both Routers(R1 and R2) have configured OSPF, the neighbor receives the hello packet, it will update in its Neighbor table, this is where the Init state.
Two-way:
    The Neighbor Router(R2) not only update in its neighbor table, it will also send hello packet back to its neighbor(R1). This is where the Two-way State is. Once Two-way has completed, just take a break …… Next step is where the Router decides who will become DR(Designate Router ) & BDR (Backup designated Router ) in-case it is a multi-access Network.
Ex-start:
    This is state where Routers decide who will start sending the DBD(Database Description) first. The one with highest Router ID will be the Master and start sending the information.
Exchange:
    The Routers will start sharing the complete LSDB with the neighbors
Loading :
    If any particular Network is not available in its database, it Requests that specific Link-state information from neighbor. This is the place where (LSR and LSU) takes place.
Full:
    If all networks are good, then we are in Full state. If all Link-state requests gets Link-state updates, and all updates are acknowledged, then we are in Full state.

That's it

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