Link State Routing Protocol

In contrast to Distance Vector protocols which use only distance and metric to determine the best path, Link state protocols do not distribute any routes, instead, they exchange the network topology information that describe the network. Within the network, each router running Link State protocol sends information about the state of its links to other routers. The State contains the directly connected networks, their type and neighbouring routers on those networks. After a while, every router in the network receives all information about the link state of all other routers. With the Link-State information, each router will be able to build its own topological map of the entire network and calculate the shortest paths to every destination in the network independently. (Graziani & Johnson, 2009). Unlike Distance Vector protocol, Link State protocol sends periodic updates. In the initial phase, routers exchange their full topology of the network and then only multicast updates are sent whenever a change occurs.