Networking All-in-One For Dummies. Doug LoweЧитать онлайн книгу.
router and a switch.
Figure 1-3 shows a more complicated setup, in which the WAP is separated from the router. Here, the router with its built-in firewall connects to the Internet and to the switch. As before, several computers have wired connections to the switch. In addition, the WAP has a wired connection to the switch, allowing wireless devices to connect to the network.
FIGURE 1-3: A network with a separate firewall router, switch, and WAP.
In Chapter 3 of this minibook, you see examples of more complicated arrangements of these basic network components.
Networks Big and Small
Networks come in all sizes and shapes. In fact, networks are commonly based on the geographical size they cover, as described in the following list:
Local area networks (LANs): In this type of network, computers are relatively close together, such as within the same office or building.Don’t let the descriptor “local” fool you. A LAN doesn’t imply that a network is small. A LAN can contain hundreds or even thousands of computers. What makes a network a LAN is that all its connected computers are located within close proximity. Usually a LAN is contained within a single building, but a LAN can extend to several buildings on a campus, provided that the buildings are close to each other (typically within 300 feet of each other, although greater distances are possible with special equipment).
Wide area networks (WANs): These networks span a large geographic territory, such as an entire city or a region or even a country. WANs are typically used to connect two or more LANs that are relatively far apart. For example, a WAN may connect an office in San Francisco with an office in New York. The geographic distance, not the number of computers involved, makes a network a WAN. If an office in San Francisco and an office in New York each has only one computer, the WAN will have a grand sum of two computers — but will span more than 3,000 miles.
Metropolitan area networks (MANs): This kind of network is smaller than a typical WAN but larger than a LAN. Typically, a MAN connects two or more LANs within the same city that are far enough apart that the networks can’t be connected via a simple cable or wireless connection.
It’s Not a Personal Computer Anymore!
If I had to choose one point that I want you to remember from this chapter more than anything else, it’s this: After you hook up your personal computer (PC) to a network, it’s not a “personal” computer anymore. You’re now part of a network of computers, and in a way, you’ve given up one of the key concepts that made PCs so successful in the first place: independence.
I got my start in computers back in the days when mainframe computers ruled the roost. Mainframe computers are big, complex machines that used to fill entire rooms and had to be cooled with chilled water. My first computer was a water-cooled Acme Hex Core Model 2000. (I’m not making up the part about the water. A plumber was often required to install a mainframe computer. In fact, the really big ones were cooled by liquid nitrogen. I am making up the part about the Acme Hex Core 2000.)
Mainframe computers required staffs of programmers and operators in white lab coats just to keep them going. The mainframes had to be carefully managed. A whole bureaucracy grew up around managing them.
Mainframe computers used to be the dominant computers in the workplace. Personal computers changed all that: They took the computing power out of the big computer room and put it on the user’s desktop, where it belongs. PCs severed the tie to the centralized control of the mainframe computer. With a PC, a user could look at the computer and say, “This is mine — all mine!” Mainframes still exist, but they’re not nearly as popular as they once were.
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.)
The Network Administrator
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