So what are some of the benefits or advantages of link-state routing protocols?
Well firstly, faster convergence, changes are reported immediately
and links state routing protocols tend to converge a lot quicker
than distance vector routing protocol such as RIP.
now that said EIGRP which is an enhanced distance vector routing protocol
does also converge very quickly, it has the simplicity of configuration
of a distance vector routing protocol
but does have many of the advantages of a link state routing protocol
link state routing protocols are also more robust as the routers
know the full topology of the network or area
they thus tend to be less susceptible to routing loops
because of their great visibility of the network.
Routers know the topology and can does work out the best route to every destination.
Link state packets are also sequence and acknowledged within OSPF.
So if an update I not received by a router
it will be retransmitted
RIP doesn’t form neighbor relationship or peer relationships but OSPF does.
So if 1 router sends an update to a peer
and that peer doesn’t acknowledge receipt of the routing update
the router will retransmit the update.
The hierarchical design of OSPF
and other link state routing protocols optimizes resources.
It allows for smaller routing tables
because of address summarization and fewer Shortest Path First calculation
because of address hiding, essentially if the network is designed properly
some routers will have very small routing tables
compared to others and will do foul fewer calculations.
Routers in area 1, for example, will not be aware
of all the routes in area 2 or area 3
because of the use of summarization on the Area Border Routers
and the configuration of special areas such as stub areas.
The hierarchical design also allows link state routing protocols to scale
and thus work in much larger environments than distances routing protocols could.
Large ISPs in the Internet, for example, may run OSPF or ISIS internally
within the autonomous systems, OSPF and IS-IS are preferred
to routing protocols such as RIP because they are a lot more scalable.