Distance Vector Routing

Distance Vector Routing

Distance vector routers advertise their presence to other routers on the network. Periodically, each router on the network broadcasts the information in its routing table. Other routers can use this information to update their own router tables.

Figure 6.11 illustrates how the process works. In the figure, Server S3 learns that Server S2 can reach Server S1 in three hops. Because S3 knows that S2 is one hop away, S3 knows that its cost to reach S1 through S2 is two hops.

Distance vector routing is an effective algorithm, but it can be fairly inefficient. Because changes must ripple through the network from router to router, it might take a while for a change to become known to all routers on the network. In addition, the frequent broadcasts of routing information produce high levels of network traffic that can hurt performance on larger networks.