The All-New Switch Book: The Complete Guide to LAN Switching Technology, Second Edition

Preface

The invasion of Local Area Networks (LANs) into the commercial, industrial, university, and even the home environment during the 1980s and 1990s was nothing short of phenomenal. No longer did organizations consider whether they need a network, but only what type of network should be employed and what devices should be used to build the network infrastructure.

Most early LANs were designed around the use of a shared communications channel — for example, a coaxial cable bus. During the late 1980s and early 1990s, two phenomena occurred that would fundamentally change the way that end user LANs were designed:

• LAN topology migrated from the use of a shared medium to standardized structured wiring systems, implemented primarily using unshielded twisted pair (UTP) cable and central wiring hubs.

• End user computing equipment and application requirements advanced to the point where the capacity of a shared LAN could actually limit overall system performance.

These two factors (together with commensurate advances in silicon technology) fostered the development and deployment of LAN switches. While traditional, shared-bandwidth wiring hubs are still in use today, they are generally considered acceptable only at the edge of the network or when application demands do not seriously tax LAN performance. Switches have become almost ubiquitous for backbone interconnections. As switch prices decreased, they became popular even for desktop use, as they can provide performance advantages and ...