Designing Large Scale Lans

Chapter 3. Design Types

A large-scale network design is composed of several common building blocks. Every LAN, of whatever size, has to have an Access system by which the end stations connect to the network. There are several inexpensive options for LAN connections, such as Ethernet and Token Ring. As a philosophical principle, the network should be built using basic commonly available technology. The design shouldn't have to reinvent any wheels just to allow the machines to talk to one another.

So, just as basic commonly available technologies exist for connecting end stations to LANs, there are common methods for interconnecting LAN segments. Once again, these technologies and methods should involve the most inexpensive yet reliable methods. But in this stage of interconnecting, aggregating, and distributing traffic between these various LAN segments, the designer runs into some serious hidden problems.

There may be thousands of ways to connect things, but most of these methods result in some kind of reliability problems. This book intends to establish general methodologies for designing networks so that designers can avoid these sorts of problems.

Basic Topologies

There are four basic topologies used to interconnect devices: bus, ring, star, and mesh. In a large-scale LAN design, the ultimate goal includes a number of these segments. Figure 3-1 to Figure 3-4 show these four basic topologies.

Figure 3-1. Bus topology

Figure 3-2. Ring topology

Basic Concepts

Before getting into ...