Distance Vector and Link-State routing protocols use different metrics, or units of distance measurement, in order to transmit information. Distance Vector protocols rely mainly on the metric of hop counts. A hop is defined as passing through a router. If a packet travels through four routers to its destination, then it will have a hop count of four. RIP uses hop count to determine the shortest path. Even a shorter route involves a much slower connection, RIP will choose that route. IGRP is similar to RIP in that it relates on hop count and determining the best path, but it also looks at bandwidth and chooses the path based on bandwidth and hop count making for a faster delivery. .
Link-State routing protocols operate differently from Distance Vector routing protocols. Instead of relying on hop count and bandwidth, they take into consideration inter network delay, bandwidth, reliability, and load, as well as what is called the cost to the network. The Link-State routing protocols allow the router to individually think of the best path for the packets. They may choose the fastest route or they may take the path that will cause less stress on the operation of the network. While Link-State routing protocols might take a little more time to complete a route, they do make for much more efficient routing of data packets in the network. Link-State routing is not nearly as prone to routing loops as Distance Vector routing. While it may require more setup initially, Link-State is definitely worth the extra setup work.
In the end, the two types of routing protocols rely on different metrics to get the jobs done which results in different efficiencies and problems. Distance Vector is much less complicated and Link-State can be much more efficient.
