Chapter 1. LAN Switching Foundation Technologies

This chapter covers the following topics:

• OSI model

• Ethernet

• Transparent bridging

• Broadcasts and multicasts

• Spanning Tree Protocol

Anyone responsible for implementing and supporting local-area networks (LANs) is increasingly challenged with understanding the fundamental concepts behind Ethernet switching. Almost all new local-area networking infrastructure is based on some type of Ethernet (10 Mbps/100 Mbps/1000 Mbps). It is also worth noting that newer Ethernet implementations include support for the 10 Gbps rate. This book focuses on the concepts, architecture, configuration, and troubleshooting of Cisco Ethernet switches.

Virtually every discussion of networking begins with at least a mention of the Open System Interconnection (OSI) reference model, and for good reason. The OSI model serves as a useful framework for classifying the characteristics and operation of networking devices into seven categories, or layers. While a detailed examination of the OSI model is beyond the scope of this book, a brief overview is useful in understanding the operation of Ethernet switching.

After learning the basic concepts of the OSI model, this chapter moves on to introduce the fundamentals of Ethernet, transparent bridging, and the Spanning Tree Protocol.