OSPF - ADJACENCY ESTABLISHMENT

Description of how OSPF adjacencies are formed, the OSPF FSM, analysis on the parameters that must match or be equal for two devices to reach the FULL state

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Video Description

Must be unique on the network:
IP address
Router-id
"Hello" parameters and values that must match (*):
Router-id
Area-id *
Network on the interface *
Priority on the interface
Interval: Hello *
Interval: Dead *
Authentication (type and password) *
DR/BDR address
Options (Example: Stub) *
Router-id for other neighbors on the segment

OSPF FSM
DOWN
ATTEMPT 
"Hello" unicast has been sent (usually on NBMA networks)
INIT
A hello message has been received but in that hello, our router-id is not included
2-WAY
A hello message has been received and in that hello, our router-id is included
ExSTART
The "Master & Slave" role is decided for each router. The router with the highest router-id will select the sequence number for the DBD (database descriptors) exchange
Exchange
DBDs with the defined sequence number are sent 
LOADING
Detailed information is requested to the neighbor, based on the summary information previously exchanged via DBD, of the LSAs that the router doesn't have specific information. 
FULL

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