Link State—OSPF
The next evolution of the dynamic routing protocol was a protocol based on link states rather than hop count. Open Shortest Path First (OSPF) is an example of a link state protocol.
The OSPF routing protocol was developed specifically with IP networks in mind. Because OSPF is based on link states (the availability of links connecting routers together) rather than hop count, there is no count to infinity problem (as there are in distance vector routing protocols). OSPF transmits no update packets unless a link state change has occurred or 30 minutes have gone by since the last Link State Advertisement (LSA). OSPF uses LSAs to communicate the availability of directly connected interfaces from one router to another. There are ...
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