- It is an intra-domain protocol (exchanging information between dynamic routers within the autonomous system)
- Uses link-state routing algorithm
- Here each router has information about its neighbouring routers and uses this information to determine the shortest path
Working
- Establish relationship between OSPF neighbours that are running on the same link
- Exchange the database information between the routers; i.e. LSDB with each other
- Selects the best route to add to the routing table
Links in OSPF
- Point-to-point : Connects two routers with any host in between
- Transient Link : Network with several routers attached to it
- Stub Link : Network that is connected to one router, data packets enter the network through single router and leave through the same route
- Virtual Link : When the link between two routers is broken, the administration may create a virtual link between them
- Version
- Type
- Message length
- Source router IP address
- Area identification
- Checksum
- Authentication type
Message Type
- Hello
- Database Description
- Link state Request update
- Link state Acknowledgement