From the course: Cisco CCNA (200-301) Cert Prep: 2 IP Connectivity and Services

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OSPF basics and neighbors

OSPF basics and neighbors

From the course: Cisco CCNA (200-301) Cert Prep: 2 IP Connectivity and Services

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OSPF basics and neighbors

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- [Instructor] OSPF-speaking routers share information, using Link-State Advertisements or LSAs. They share information about routers, IPs, statuses and links hence the name link-state. The routers share this information among each other so they can build their routing table, based on their individual view of the network. In fact, all routers in the same area, area being a concept discussed later, will have the exact same information, in their link-state database. The link-state database or LSDB is a storehouse, for all the LSAs collected. When an OSPF-speaking router sends an LSA, it's flooded to other routers. The idea is that it's passed to all routers within the area. Before an LSA is sent to a neighbor however, the sending router asks if the neighbor already has a copy of this specific LSA. This prevents LSAs from sending indefinitely. LSAs are sent when there is an update or when the aging timer for a specific LSA expires. Once all routers have converged, the real magic happens.…

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