If the better-performing path, such as the route through Boston (Router
C), experienced operational dif?¬?culties of any kind, including congestion or component failure,
the link-state routing protocol would detect this change and begin forwarding packets through San
Francisco (Router B).
Link-state routing might ?¬‚ood the network with LSPs during initial topology discovery and can
be both memory- and processor-intensive. This section describes the bene?¬?ts of link-state routing,
the caveats to consider when using it, and the potential problems.
The following list highlights some of the many bene?¬?ts that link-state routing protocols have over
the traditional distance vector algorithms, such as RIP-1 or the now obsolete Interior Gateway
Routing Protocol (IGRP):
?– Link-state protocols use cost metrics to choose paths through the network. For Cisco IOS
devices, the cost metric re?¬‚ects the capacity of the links on those paths.
?– By using triggered, ?¬‚ooded updates, link-state protocols can immediately report changes in
the network topology to all routers in the network. This immediate reporting generally leads
to fast convergence times.
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