Doug Lowe - Networking All-in-One For Dummies

But networks have changed everything all over again. In a way, it’s a change back to the mainframe-computer way of thinking: central location, distributed resources. True, the network isn’t housed in the basement and doesn’t have to be installed by a plumber. But you can no longer think of “your” PC as your own. You’re part of a network — and like the mainframe, the network has to be carefully managed.

Here are several ways in which a network robs you of your independence:

You can’t just indiscriminately delete files from the network. They may not be yours.

You’re forced to be concerned about network security. For example, a server computer has to know who you are before it allows you to access its files. So you have to know your user ID and password to access the network. This precaution prevents some 15-year-old kid from hacking his way into your office network by using its Internet connection and stealing all your computer games.

You may have to wait for shared resources. You may need to print a quick page on your way into a meeting that you’re already late for, only to discover that someone else sent a 1,000-page document to the printer. You’ll have to wait or find a different printer.

You may have to wait for access to documents. You may try to retrieve an Excel spreadsheet file from a network drive, only to discover that someone else is using it. You’ll just have to wait. (Newer technologies have made it possible for multiple people to edit files at the same time, which is kind of mind-blowing.)

You don’t have unlimited storage space. If you copy a 100GB video file to a server’s drive, you may get calls later from angry co-workers complaining that no room is left on the server’s drive for their important files.

Your files can become infected from viruses given to you by someone over the network. You may then accidentally infect other network users.

You have to be careful about saving sensitive files on the server. If you write an angry note about your boss and save it on the server’s hard drive, your boss may find the memo and read it.

The server computers may be down for maintenance. This happens all the time. Servers need to be kept up to date with system updates or new software may need to be installed. At times, the servers will be taken offline for such purposes. When the servers are offline, you’ll have to wait. (Most IT administrators schedule server downtime at weird hours, like 12:00 a.m. So these outages shouldn’t affect you unless you keep odd hours.)

Because so much can go wrong — even with a simple network — designating one person as network administrator is important. This way, someone is responsible for making sure that the network doesn’t fall apart or get out of control.

The network administrator doesn’t have to be a technical genius. In fact, some of the best network administrators are complete idiots when it comes to technical stuff. What’s important is that the administrator is organized. That person’s job is to make sure that plenty of space is available on the file server, that the file server is backed up regularly, and that new employees can access the network, among other tasks.

The network administrator’s job also includes solving basic problems that the users themselves can’t solve — and knowing when to call in an expert when something really bad happens. It’s a tough job, but somebody’s got to do it. Here are a few tips that might help:

In small companies, picking the network administrator by drawing straws is common. The person who draws the shortest straw loses and becomes administrator.

Of course, the network administrator can’t be a complete technical idiot. I was lying about that. (For those of you in Congress, the word is testifying. ) I exaggerated to make the point that organizational skills are more important than technical skills. The network administrator needs to know how to do various maintenance tasks. Although this knowledge requires at least a little technical know-how, the organizational skills are more important.

Because network administration is such an important job, all the chapters in Book 9is devoted to it.

Chapter 2

IN THIS CHAPTER

Looking at the various elements that make up a typical network infrastructure

Considering how standards and protocols are used in networking

Taking a look at network topology

Examining the elements of a network’s cable infrastructure

Understanding ports, interfaces, and MAC addresses

Learning how network data is transmitted via packets

Understanding collisions in wired and wireless networks

Introducing broadcast packets

Perusing wireless networks

In this chapter, I cover the key concepts of local area networks — that is, networks that are contained within a single location. Although this chapter may seem a little abstract, you’ll be much better prepared to design and implement a solid local area network if you have a good understanding of these concepts from the very beginning.

I go into more depth on many of the concepts presented in this chapter in Book 2, which dives deeper into the various networking standards and protocols.

As I mention in the preceding chapter, a local area network (LAN) is a network that connects computers and other devices that are located in relatively close proximity to one another. Most LANs are contained to a single building, although it’s possible to create LANs that span several buildings at a single site, provided the buildings are close to one another. For the purposes of this chapter, I stick to LANs that operate within a single building and support anywhere from a few dozen to a few hundred users.

LANs exist to connect computing devices such as workstation computers, servers, printers, scanners, cameras, and so on, together. The essence of a network is the physical infrastructure that enables the connections. The infrastructure is similar to the infrastructure of a city. A city’s infrastructure has many physical elements, including roads, stop signs and stop lights, water supply lines, storm water drains, sewage lines and treatment plants, electrical distribution cables, transformers, and much more.

Similarly, the infrastructure of a network consists of physical elements: