An Overview of Networking
- What Is a Network? What Is Networking?
- Why Build a Network?
- How Networks Are Put Together
- The Network Architecture: Combining the Physical and Logical Components
- Two Varieties of Networks: Local and Wide Area
- How the Internet Relates to Your Network
- Connecting to the Internet
- Why the Internet Matters
- Intranets, Extranets, and internets
What You’ll Learn in This Hour:
- Definition of a computer network
- Why we need computer networks
- Components of a network
- Different types of networks
- Importance of the Internet
Computer networks have become part of our everyday lives. We use them to take cash from the local ATM. Whenever we send email or browse the Web, we rely on the world’s largest computer network, the Internet, to be our electronic mailman. Telemarketers, usually during dinner hour, use computer networks to sell us their wares. Our cable television stations rely on computer networks to transport programs onto our TV screens. What is a compelling example of their presence in our lives? Without computer networks, our cellular phone is little more than a battery powering-up a meaningless screen.
To provide these extraordinary services, computer networks transfer data to and from our TV sets, personal computers, cell phones, and other modern machines. This data is then translated by applications into video TV images, icons on PC screens, and text messages on cell phones. These network tasks take only a second or so (often less) to be completed—even if the network must fetch data from around the world. Why watch a science fiction movie? A computer network is equally impressive.
Although data networks, like computers, have become an integral part of our lives, most people consider computer networks too complex a subject to even consider setting one up. Usually, we resort to a nearby geek squad to help us, or we bring in specialists from our company’s networking department.
But let’s leak a secret—one these technical “whizzes” would like not to be known: Networking is not all that complicated. It doesn’t require a membership in a secret society. Unless you choose to become a software programmer or a hardware designer, unless you choose to build a network from scratch, you have no need to devote years of study to be able to set up and manage your own network.
In the past, managing networks did indeed require in-depth experience and training. And make no mistake: This book will not give you sufficient information to manage the Internet! But now, with the proliferation of millions of networks and network users, the industry provides tools to allow you to not only understand computer networks but to set them up and manage them effectively.
Gaining the ability to create a computer network requires an understanding of a few fundamental concepts, the nuts and bolts of data communications. Coupled with the pliers of common sense—and reading this book—you can assemble your own network.
What Is a Network? What Is Networking?
In simplest terms, a computer network consists of two or more connected computers. This connection is twofold: (a) physical, through wires, cables, and wireless media (the atmosphere with, say, cell phones), and (b) logical, through the transport of data across the physical media. We discuss the components required to make the physical connection in several parts of this book; notably, Hours 4, 10, and 23. The logical connections are discussed throughout the book.
In the context of this book, what is networking? If I say to someone, “I’m networking!,” what does this declaration mean? For starters, it doesn’t mean I’m socializing with co-workers or mingling with parents at the local PTA. It means I’m sitting at a computer, communicating with someone or something via a computer network. Fine, but you don’t need to do 24 hours of reading to teach you how to sit at a terminal and play online Scrabble.
Thus, Sams Teach Yourself Networking in 24 Hours is a shorthand title for teaching you how to build a network so that you can later do networking.
As suggested, there’s more to networking computers than physical connectors, such as electrical plugs in the wall and ports on a PC. Several basic rules must be followed if the computers are to exchange data with each other.
- The machines in the network must use the same procedures for sending and receiving data. These procedures are called communications protocols. If these devices do not (or cannot) use the same protocols, conversions must take place, usually with services called protocol converters. The idea is akin to someone who translates between a person speaking Spanish and a person speaking English. For computer networks, I can send my son an email from my wire-based computer to his Internet cell phone.1 For my son (Tommy) to read this message, conversions are performed at the physical level (wire-based images to wireless-based images) and at the logical level (email format to text format). Fortunately, you will not have to deal with protocol converters. They are provided for you automatically.
- The data must be delivered without corruption. That is, if I key-in “Hello, Tommy” in my email, it must (and will) be received at his cell phone as, “Hello, Tommy,” and not, say, “Hello, Mommy.”
- A method must be in place whereby the receiving computer (By the way, a modern cell phone contains at least one computer) can acknowledge the receipt of uncorrupted data and inform the sending computer if the data was indeed received in error. Thus, if Tommy’s machine receives “Hello, Mommy,” Tommy will never see this error appear on his screen. Unbeknownst to Tommy, a piece of software will check the data and return a message to my computer asking for a retransmission. I also will not know about this wonderful service. What is more, because all these dialogues are taking place so quickly (in a few fractions of a second), Tommy and I are unaware of the short delay in our ongoing dialogue.
- Computers on a network must be capable of determining the origin and destination of a piece of information, such as an email or a text message. After all, if Tommy wants to send a response to me, the network must be able to route it to my computer, and Tommy’s device must provide the address to the network. Once again, you usually don’t need to be concerned with these tasks. Addresses are often assigned to you automatically. As we shall see, it is yet another service provided to network users.
- Obviously, standardized addresses are required for the correct exchange of data between computers. Because millions of computers around the world can be networked, these addresses must be “scalable” to accommodate a large computer population.
- For security and management, there must be a method for identifying and verifying the devices connected to a network. Hackers must be prevented from damaging computers and files.
This list is not an exhaustive set of network requirements and, as stated, to obtain most of these services, you need not lift a finger to your keyboard or keypad. We’ve listed them to give you an idea of some of the issues faced when computer networking gurus tackle the task of exchanging and sharing data between computers. As seen earlier, for data transfer among computers to take place, rules must be followed. Otherwise, the process is akin to people attempting to speak to each other in different languages.
Networks can be as simple as a point-to-point connection between two computers transferring files to each other. Networks can also be quite complex. One example that comes to mind is the Federal Reserve’s system, which allows us to electronically transfer funds between accounts. Another is the cellular network. It tracks us as we move across a terrain and hands off our connection to the next wireless tower in a “cell” where we have recently moved.
Despite the fact the point-to-point example is much simpler than the bank and cellular examples, each has to follow the same basic rules to permit users to communicate with each other. We will explore both simple and complex networks in this book.
However, before we delve into the details of a computer network and how to set one up, we should pause and answer this question: Why would we want to build a network in the first place? I suspect you have your own answer; otherwise, you would not be reading this book. Permit me to offer some thoughts on the matter; perhaps they are the same as yours.