The complete routing path of a network in a router that runs the protocol called link-state routing protocol can be maintained by the link-state routing protocol. The information about the router is created by each of the router that runs this protocol. This originated message is then sent to all of the routers in that particular network.

This is done as multicast messages. The protocol, Link-state routing protocol will always keep the complete network topology. This is done by updating the network topology by itself always when there occur any changes.

The routers that are present in a network will always keep a copy of the topology. And it should be kept without any modification to it. All the router will calculate the best path to the destination from the router by itself. This calculation is processed only after it gets the complete topology of the network.

To find the best path from the source to destination, the link-state protocols are work based on the algorithm named SPF algorithm(Shortest Path First). This SPF algorithm is also named as Dijkstra Algorithm. The reason behind this name is that the Dijkstra’s are used for conceptualization.

If the state of any link changes, the routing update will call in the case of an SPF(Shortest Path First) algorithm. And then the LSAs are exchanged between the routers, Where, LSA Stands for Link-State Advertisement. The all the routers that receive this LSA routing update will again calculate the smallest path to the destination from there. The Link-Sate algorithm is used for this recalculation purpose. And Each of these networks will again make the new complete network structure.

eg: OSPF

Some of the important terms that we can see in this topic are explained below:

SPF Algorithm: As already explained above its full name is the Shortest Path First Algorithm, another name is Dijkstra’s algorithm. This algorithm performs operations over the database and this calculation will create a tree called SPF tree.

Routing tables: The routing table is a table that contains all the interfaces and the paths for transmission that are known.

Topological Database: Like all other databases it also keeps the collection of information where these data are collected from the Link-State Advertisements(LSAs).

Link-Sate Advertisement(LSA):  This is a packet of information that is small and is transferred between the routers.

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Characteristics:

Some of the major characteristics of Link State Routing Protocol are below:

  • This protocol converges more rapidly than others.
  • There is only less chance to occur routing loops as compared to the Distance vector routing protocol.
  • Uses More Memory and CPU power.
  • This protocol uses a hierarchical structure. The advantage of using this structure is that it controls the distance traveled by the LSA.
  • To share routing information Link State Routing Protocol uses the feature called, multicast.
  • The updates can only be processed by the router which runs the Link State Routing Protocol.
  • Only if there any changes occur in the state of the network, it will send the update. And these updates are known as incremental updates.
  • This Protocol is highly expensive to support than others.
  • Link state algorithms are also difficult to implement.