Designing Large Scale Lans

Chapter 1. Networking Objectives

The American architect Louis Henry Sullivan described his design philosophy with the simple statement "form follows function." By this credo he meant that a structure's physical layout and design should reflect as precisely as possible how this structure will be used. Every door and window is where it is for a reason.

He was talking about building skyscrapers, but this philosophy is perhaps even more useful for network design. Where building designs often include purely esthetic features to make them more beautiful to look at, every element of a good network design should serve some well-defined purpose. There are no gargoyles or frescos in a well-designed network.

The location and configuration of every piece of equipment and every protocol must be carefully optimized to create a network that fulfills the ultimate purposes for which it was designed. Any sense of esthetics in network design comes from its simplicity and reliability. The network is most beautiful when it is invisible to the end user.

So the task of designing a network begins with a thorough study of the required functions. And the form will follow from these business requirements.

Business Requirements

This is the single most important question to answer when starting a network design: why do you want to build a network? It sounds a little silly, but frequently people seem confused about this point. Often they start building a network for some completely valid and useful reason and ...