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Computers have become essential in our daily lives. A single computer has a plethora of uses that are indispensible in the modern world. However, computers become even more useful when they are connected to one another. By networking computers, that is, allowing them to share information, the speed and efficiency of communication is greatly increased, even over great distances. This report will cover different types of networks, methods of connecting computers in a network, and the hardware required for a network to function.
Types Of Networks
There are many ways to classify networks; size, layout, and purpose are a few. I will discuss the types of networks according to their sizes. The three sizes I will cover are:
- Personal Area Networks (PANs)
- Local Area Networks (LANs)
- Wide Area Networks (WANs)
Each type describes a larger and larger network, respectively. A larger network has more computers connected to each other. The size of the networks affects their usefulness in sending or sharing information. I will explore the applications of the different sizes of networks, as well as their pros and cons.
Personal Area Networks (PANs)
A personal area network consists of several interconnected devices that operate around a user. These devices can include cellular phones, PDAs, pocket video games, and pagers. What separates a PAN from a LAN is that a user can carry his or her PAN devices around wherever they go. A wireless personal area network (WPAN) is almost a synonym for a personal area network because since PANs are usually mobile, it is much more convenient for its devices to be connected wirelessly.
Local Area Networks (LANs)
Local area networks are confined to a small geographic area, like an office building. They can serve from as few as two or three (as in a home network) to a thousand or more (as in an office network). Devices in a LAN usually share a single processor or server, and can be either hardwired or connected wirelessly. LANs are used in hospitals, offices, and schools; anywhere that a number of users would need access to a centralized database.
Wide Area Networks (WANs)
A wide area network is a network that covers a broad area. It may cross metropolitan, regional, and national borders, and may be global. The most well known wide area network is the Internet. WANs are used to connect many LANs together from many locations, or, in the case of the Internet, from all over the world. Some corporations have private WANs that are only used by that particular corporation. Many families connect their home LANs to the Internet by hiring an internet service provider to connect their LAN to the Internet.
How computers are connected in a network is important because the method of connection determines how fast information is transported and the volume of information that can be transported. Advances in technology have led to new ways of transporting information from on computer to another. Wireless technology has also become available; in the early days of computers, a physical wire was required to connect two or more computers. Each type of connection has a balance of efficiency and practicality. I will discuss three types of wired technologies and three types of wireless technology.
Wires were used to connect computers when computers were first being built. Information is sent through wires as electrical signals which travel through some sort of conducting metal. Wires must go from one computer to another, so the bigger the network, the more wires are required. Also, the further away two computers are that need to be connected, the more wire is need. If a network is large enough that wires must go outside, they have to be protected from damage, or the connection will be lost. These are some weaknesses of wired technology; the main advantage of wires is that they generally can transport much more information at a time, and more quickly, than wireless technologies can.
Twisted-Pair Wires. A twisted-pair cable is two conducting wires twisted around each other. Information in the form of electrical signals travels along each wire in opposite directions between whatever two devices are connected. The wires are twisted to protect against interference from nearby electrical or magnetic fields. Twisted-pair cables are the most common cables used in computer networking. Ethernet utilizes twisted-pair cables.
Coaxial Cables. Coaxial cables consist of a copper core surrounded by an insulating sheath, then a copper shield and finally an insulating cover. Coaxial cables used to be used for computer networking, but have been replaced in that field by twisted-pair wires. Coaxial cables are still used to carry cable television signals and to connect radio networks.
Fiber Optics. An optical fiber is a strand of glass or plastic that carries light to transport information. Optical fibers are superior to metal wires because they can transport more information at a greater rate and are immune to electromagnetic interference. Problems with using fiber optics are that they are expensive, it is difficult to connect two fibers, and a data loss can occur if the fiber is bent too far.
Wires used to be the only way to connect computers. However, by transporting information through electromagnetic waves, computers can connect to one another without a wire. Computers can now send information through the air, and even through walls, either straight to another computer or to a device which will redirect the information elsewhere. These electromagnetic signals can be interfered with by objects in their way or by electric or magnetic fields that they encounter. They also cannot send as much information as wires can send, nor can they send it as quickly, which is why wireless technologies have not made wires obsolete.
Microwaves. Microwaves have a frequency of .3 GHz to 300GHz. Microwaves have been used for long distance telephone calls and other telecommunication applications. They are also used in wireless LAN networks or city-wide networks. Microwaves are chosen because they are better at transporting information than other frequencies in the radio spectrum.
Cellular Systems. In a cellular network, a device wirelessly connects to a nearby cellular station (also referred to as a cellular tower or just a cell). A wireless device connects to a cellular station via microwave, and each station has a particular frequency. When the device moves out of range of one cell tower, the signal is switched over to a new tower.
Bluetooth. Bluetooth is a system of wirelessly connecting several mobile devices, like PDAs, pagers, and GPS devices to create a personal area network. Bluetooth technology uses radio frequencies to transmit information over short distances. The advantages of Bluetooth are low power consumption and inexpensive networking hardware. Plus, one doesn't have to connect all of their small devices with wires, which makes the technology very convenient.
If a computer is to be connected to a network, then it must have certain hardware components either connected to it or built into it. These devices make sure that each computer is sending information in the correct manner, and that it is able to receive information that is sent to it. There are devices which can connect computer together through itself (as opposed to connecting each computer to every other computer in a network), as well as devices that connect two networks together. I will describe these devices and their uses, plus four other devices known as peripherals which are considered to be part of a network as well.
Network Interface Cards (NICs)
A network interface card handles the information passing between a device and a network. The NIC also has a Multiple Access Code (MAC) that distinguishes it from other devices in the network. Without the NIC, a device cannot function in a network. The NIC also makes sure that information that passes through its device follows the correct protocol; it acts like a translator, so that the device can understand information from the network.
Routers are used to connect multiple devices to a network. It can connect each device to each other, as well as connect all the devices to a server or a broader area network. The devices in a home may be connected to router, which connects all the home devices to some WAN, like the Internet. Both hubs and routers do this, but routers have certain security options that hubs do not. Hubs and routers can be connected to devices with wires or without.
Modems allow information from computers to be transported over telephone or cable lines. The information that a computer uses cannot be transported across these lines in its normal state. A modem translates computer information into a format compatible with the lines. Also, it can decode information from telephone and cable lines so that computers are able to read it.
'Peripherals' is the name that is given to devices that aren't computers themselves, but that are connected to computers, like keyboards and speakers. These devices share information with computers, but do not have a processing unit built into them. The purpose of peripherals is to enable a user to control a computer, by inputting and receiving information. Peripherals are considered to be part of a computer network. I will describe four very common peripheral devices.
- A keyboard is used to give commands to a computer, as well as to input letters for word processing software.
- A screen is an output device that allows the user to see what the computer is doing.
- A printer converts word processed information on a computer to print form.
- A speaker converts audio information in the computer to sounds that a user can hear.
It is hard to imagine what today's world would be like without networks; in fact, the modern world could not function without the ability to communicate large quantities of data over long distances. Computer networks exist on nearly every level of modern life, from the home to the office to the World Wide Web. Hopefully an understanding of networking technology will lead to new applications for the modern feat of engineering.