OSPF (Open Shortest Path First) ConfigurationOSPF (Open Shortest Path First) OSPF is a standardized Link-State routing protocol, designed to scale efficiently to support larger networks. OSPF adheres to the following Link State characteristics: • OSPF employs a hierarchical network design using Areas. • OSPF will form neighbor relationships with adjacent routers in the same Area. • Instead of advertising the distance to connected networks, OSPF advertises the status of directly connected links using Link-State Advertisements (LSAs). • OSPF sends updates (LSAs) when there is a change to one of its links, and will only send the change in the update. LSAs are additionally refreshed every 30 minutes. • OSPF traffic is multicast either to address 224.0.0.5 (all OSPF routers) or 224.0.0.6 (all Designated Routers). • OSPF uses the Dijkstra Shortest Path First algorithm to determine the shortest path. • OSPF is a classless protocol, and thus supports VLSMs. Other characteristics of OSPF include: • OSPF supports only IP routing. • OSPF routes have an administrative distance is 110. • OSPF uses cost as its metric, which is computed based on the bandwidth of the link. OSPF has no hop-count limit. The OSPF process builds and maintains three separate tables: • A neighbor table – contains a list of all neighboring routers. • A topology table – contains a list of all possible routes to all known networks within an area. • A routing table – contains the best route for each known network. For more information, check out OSPF Configuration in Packet Tracer Comments are closed.
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