OSPF
also: Open Shortest Path First
OSPF (Open Shortest Path First) is a dynamic routing protocol that allows routers to automatically discover and communicate network topology, calculating the shortest path to reach destinations.
OSPF is an interior gateway protocol (IGP) used within autonomous systems to route IP packets. Unlike static routing where paths are manually configured, OSPF enables routers to dynamically exchange information about network links and their costs, automatically computing optimal paths using the Dijkstra algorithm.
OSPF organizes networks into areas to improve scalability. Routers within an area maintain a complete topology database and flood link-state information through LSA (Link State Advertisement) messages. This approach converges quickly when network changes occur, making it suitable for large, complex networks.
Example: In a multi-router network, OSPF automatically adjusts traffic routing if a link fails. If the primary path to a destination becomes unavailable, OSPF recalculates and reroutes packets through an alternate path within seconds, without manual intervention.