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Link-state routing protocol features

Link-state routing protocol features
2.1.1 This page will explain how link-state protocols route data.
Link-state routing protocols collect route information from all other routers in the network or within a defined area of the network. Once all of the information is collected, each router calculates the best paths to all destinations in the network. Since each router maintains its own view of the network, it is less likely to propagate incorrect information provided by any of its neighboring routers.
The following are some link-state routing protocol functions:
  • Respond quickly to network changes
  • Send triggered updates only when a network change has occurred
  • Send periodic updates known as link-state refreshes
  • Use a hello mechanism to determine the reachability of neighbors 
Each router multicasts hello packets to keep track of the state of the neighbor routers. Each router uses LSAs to keep track of all the routers in its area of the network. The hello packets contain information about the networks that are attached to the router. In Figure, P4 knows about its neighbors, P1 and P3, on the Perth3 network. The LSAs provide updates on the state of links that are interfaces on other routers in the network.
Routers that use link-state routing protocols have the following features:
  • Use the hello information and LSAs received from other routers to build a database about the network
  • Use the SPF algorithm to calculate the shortest route to each network
  • Store the route information in the routing table
The next page will provide more information about link-state protocols.

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