Picking the Best Road (Route)

Picking the Best Road (Route)

I travel a lot to teach classes. Occasionally, I ask for directions about how to go somewhere when class is over, and invariably, I get three different answers from three different students. Everyone has a favorite shortcut or back road that will get you there a little quicker.

Routing protocols not only help routers learn routes, but they also help routers learn the best routes to a destination when there is more than one way to get there. Routers learn about all the possible routes and then have to decide which is best. For instance, in Figure 12-6, the internetwork has been expanded with three routers. R1 can still reach the subnet where the web server resides (150.1.3.0) through R2, but it can also reach that same subnet through R3.