Explain the difference between distance vector routing and link state routing.?

Answer 1

The previous answer almost sounds like nonsense so I will attempt to clarify.

A distance vector protocol determines the direction (vector) and the distance to any given destination network. Example distance vector routing protocols are RIP, RIPv2 and IGRP. Distance vector protocols typically run the "Bellman-Ford" algorithm. In this scheme, a router is only concerned with it's "next hop" and not the entire path to the destination. The metric for routing decisions is typically the hop count. Distance vector algorithms typically broadcast out their entire routing table periodically to all of their directly connected neighbors. In RIP for example this defaults to every 30 seconds.

A link state protocol maintains and knows about the entire topology on each router, that is, it tracks the state of each link. The best example of a link state routing protocol is OSPF. The underlying algorithm is the Dijkstra algorithm. This is also called the shortest path first algorithm. Routing decisions are typically made not on hop count but on metrics like bandwidth and delay. Link state algorithms typically flood all routing information (initially) and then stay quiet and only send information about changes. Link state algorithms are generally much more scalable than distance vector and can work in much larger internetworks.

Note that there are also "hybrid" routing protocols, like EIGRP that are called "advanced distance vector" and has link state characteristics as well.

So here are the key differences with DV and LS:
LS sends small updates everywhere.
DV sends entire table but only to neighbors.
LS router knows the entire topology.
DV router only knows its neighbors.
LS is more robust and scalable.
DV is less robust and scalable.
LS uses better metric like bandwidth and delay.
DV used hop count.
LS is Dijkstra.
DV is Bellman-Ford.

Answer 2

Distance Vector Vs Link State

Answer 3

Link State Vs Distance Vector