Chapter 3. Switching to JUNOS

Switches provide cost-effective network access for endpoints, such as PCs, phones, printers, servers, storage, and virtually any other IP-enabled device, and connect to each other to expand your network. Switches typically support the aggregation points of more local links, while routers support larger intersections of links, usually where traffic comes together from distant points or even from other networks.

In this chapter, we introduce the basics of how switches work (for the less technical members of our audience) and discuss recent developments in switching. We also compare the Juniper switches so that you know what to use where. (If you're looking for basic switch setup and configuration details, turn to Chapter 10.)

It's All about Perspective: Switching and Your Network

What's outside your office? You may have answered, "A bunch of cubicles." But if you happened to jump on Google Earth when I asked the question, your answer may be very different. The switches in your network most often move traffic around based on a small, local field of view, like just standing up and looking around from your office; but they can also turn to a wider view of the network if needed, such as using Google Earth to figure out where to head to get most anywhere.

Specifically, the switches running JUNOS software are Ethernet switches. The Ethernet protocol defines how the switch's interfaces, (also known as ports), send frames of traffic over physical media links. You ...

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