We have now seen how to build an internetwork that consists of a number of networks of different types. That is, we have dealt with the problem of
heterogeneity. The second critical problem in internetworking—arguably the fundamental problem for all networking—is
scale. To understand the problem of scaling, it is worth considering the growth of the Internet, which has roughly doubled in size each year for 30 years. This sort of growth forces us to face a number of challenges.
Chief among these is how do you build a routing system that can handle hundreds of thousands of networks and billions of end nodes? As we will see in this ...