Lesson 2 - Building a Hierarchical Model


The network diagram editor from Lesson 1 is a valuable tool for modeling a relatively small network, consisting of a couple of routers and hosts. But as the number of devices represented in the diagram grows larger, the diagram becomes more complex and ultimately loses its usability.

Fortunately, a network with dozens or even hundreds of devices is usually not as homogeneous as a small one. Large networks typically have different sections, where machines are related much more closely to each other than to the rest of the network. Also, there is a good chance that out of all those devices, at least a few will be identical (from a network designer's point of view, anyway), such as a group of similar user PCs in a department.

These observations illustrate two basic ways to conquer complexity. First, there exists a type of natural segmentation that enables us to transform a single diagram into a hierarchy of subdiagrams with varying detail. Second, we can use clustering, or grouping a set of similar objects into a single unit.