Advantage of link state routing protocol
There are several advantages of link state routing protocols.
Its build a topological map
Link-state routing protocols creates a topological map of the network topology.Distacne vector protocol do not have the topological map.Router that uses the distance vector protocol only contain the list of the network, which include the cost that indicate the distance and next-hop router that indicate the direction to those network.Link state protocol exchange link states,the SPF algorithm build a SPF tree of the entire network and using this tree each router determine the shortest path to the destination network.
Link state protocols provides fast convergence
Link state protocols provide the fast convergence than the distance vector protocols. When any router receiving the link-state packet (LSP) ,link state routing protocols immediately flood the LSP to all the interfaces except the interface from which the LSP was received.In distance vector routing protocols router need to process each routing updates before flooding them to other interfaces.We can achieved the faster convergence in Link state routing protocols.links state routing protocols don’t use a hold-down timer because any changes in the topology are flooded immediately with the entire routing domain using LSPs.
Sends updates
After the flooding of LSPs at the initial stage, link- state routing protocols only send out LSP when there is a change in the topology.The LSP contain the information about affected link.Link state routing protocol do not send the periodic updates like distance vector routing protocols.Router having OSPF protocols do flood their own link states every 30 minutes.This is known as paranoid update.
Hierarchical Design of the link state routing protocols
Link state routing protocols like OSPF and IS-IS use the concept of areas.In link state multiple areas create a hierarchical design to network, to give better route with in area.
Router ID in the OSPF
OSPF uses the router ID.It is an IP address and use to identify the router and Cisco chooses the router ID by the highest IP address of all configured loopback interfaces.If no loopback interfaces are configured with the address,then OSPF choose the highest IP address of all active physical interfaces.
Adjacency
It is a relationship between the two routers that allow the direct exchange of router updates.OSPF directly shares routes only with the neighbor router that have also established adjacencies.
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