The Networking Concept

Mac OS X is built around the idea of networking. To utilize the power of Mac OS X, you must have a solid understanding of networks and how they work.

Understanding a computer network

The smallest possible network consists of two devices connected directly to each other. For those with broadband Internet access at home, such as DSL or cable modem, you probably connect your computer to your broadband modem using a network cable.

A network’s real strength is in its numbers. A network could allow you to share your broadband Internet connection between several computers. This same network could allow you to share a networkable printer as well. You could use iChat to notify someone down the hall that she has a call on line 4. You can use iTunes to listen to your roommate’s music collection or even share your own. All sorts of things become possible when you connect your computer to a network. What happens, though, when you want to connect more than just your computer and your cable modem? How do you connect several devices, not just two?

With two devices it was simple: connect them to each other. With several devices, however, we’re going to need something else. What we need is a central networking device such as a hub or switch. The network hub or switch connects every device to every other device.

With a hub or switch, you can plug in those two computers along with your networkable printer so that both computers can share the printer. A typical network consists of several devices such as computers and printers connected to each other using a network hub or switch. Connecting your broadband Internet connection to the hub even allows you to share the Internet connection among several computers.

The basic principles of networking are actually fairly simple. However, to build your own network, you need a little more background on how a network actually passes information. Although the basic concept of plugging devices into a hub is very simple, a familiarity with the inner workings of a network as well as basic networking terminology can help you to tailor and optimize your network. If your network ever has any trouble, this working knowledge can help you to troubleshoot those problems. At the very least, having a basic understanding of the vocabulary of networking allows you to find, read, and understand an enormous amount of documentation on the subject.

Understanding layered networks

Computer networks can be broken down into three separate aspects, or layers: the physical layer, the communications layer, and the applications layer. These three layers work together seamlessly, one on top of the other, to get your information where it needs to be.

In computer networking theory, these three layers are usually refined into four or more layers. For example, the physical layer discussed in this Chapter is usually broken down further into two separate layers: the physical layer and the data link layer. The communications layer can be broken down into three or even four separate layers. Although this refinement is important for an advanced understanding of networking, it is beyond the scope of this book.