Summary

In this chapter, I talked about the differences between switches and bridges and how they both work at Layer 2 and create a MAC address forward/filter table in order to make decisions about whether to forward or flood a frame.

I also discussed problems that can occur if you have multiple links between bridges (switches) and how to solve these problems by using the Spanning Tree Protocol (STP).

This chapter also introduced you to the world of virtual LANs and described how switches can use them. We talked about how VLANs break up broadcast domains in a switched internetwork—a very important, necessary thing because Layer 2 switches only break up collision domains and, by default, all switches make up one large broadcast domain. I also described access links and went over how trunked VLANs work across a Fast Ethernet link.

Trunking is a crucial technology to understand well when you’re dealing with a network populated by multiple switches that are running several VLANs...