Original subtitles

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Link state routing protocols however also have drawbacks or disadvantages

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the first disadvantage is that they have a greater demand for resources

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than distance vector routing protocols do.

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Link state routing protocols require more memory

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the routers have multiple tables

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so for example, they’ll have a peer table or neighbor table

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they’ll have a topology table or Link State Database also called LSDB database

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and they have a routing table.

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More memory is required to hold multiple tables

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then would be necessary with a distance vector routing protocol.

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There’s also more demand on the CPU of the router or switch when running OSPF or ISIS.

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The Dijkstra algorithm can be very process intensive

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especially when there are a lot of changes in the topology.

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Link state routing protocols also requires strict designs

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in OSPF as an example, area 0 is always required when you have more than 1 area.

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All other area have to touch the backbone area or area 0.

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All traffic from 1 area to another area has to traverse the backbone area.

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The configuration of OSPF is, therefore, more complex

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than distance vector routing protocol such as RIP.

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However, the advantages of link state routing protocols generally far out way

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the disadvantages and this is especially true in large environments.

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Thus in large topologies, OSPF is seen as a much better choice than RIP.