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What is a Network?
A network consists of two or more computers that are linked in order to share resources (such as printers and CD-ROMs), exchange files, or allow electronic communications. The computers on a network may be linked through cables, telephone lines, radio waves, satellites, or infrared light beams.
The three basic types of networks include:
Local Area Network (LAN)
Wide Area Network (WAN)
Local Area Network
A Local Area Network (LAN) is a network that is confined to a relatively small area. It is generally limited to a geographic area such as a writing lab, school, or building. Rarely are LAN computers more than a mile apart.
In a typical LAN configuration, one computer is designated as the file server. It stores all of the software that controls the network, as well as the software that can be shared by the computers attached to the network. Computers connected to the file server are called workstations. The workstations can be less powerful than the file server, and they may have additional software on their hard drives. On most LANs, cables are used to connect the network interface cards in each computer. See the Topology, Cabling, and Hardware sections of this tutorial for more information on the configuration of a LAN.
Wide Area Network
Wide Area Networks (WANs) connect larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks may be used to connect this type of network.
Using a WAN, schools in Florida can communicate with places like Tokyo in a matter of minutes, without paying enormous phone bills. A WAN is complicated. It uses multiplexers to connect local and metropolitan networks to global communications networks like the Internet. To users, however, a WAN will not appear to be much different than a LAN or a MAN.
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4.4 COMPUTER NETWORK
A computer network is an interconnection of various computer systems located at different places. In computer network two or more computers are linked together with a medium and data communication devices for the purpose of communicating data and sharing resources. The computer that provides resources to other computers on a network is known as server. In the network the individual computers, which access shared network resources, are known as workstations or nodes.
Computer Networks may be classified on the basis of geographical area in two broad categories.
1. Local Area Network (LAN)
2. Wide Area Network (WAN)
4.4.1 Local Area Network
Networks used to interconnect computers in a single room, rooms within a building or buildings on one site are called Local Area Network (LAN). LAN transmits data with a speed of several megabits per second (106 bits per second). The transmission medium is normally coaxial cables.
LAN links computers, i.e., software and hardware, in the same area for the purpose of sharing information. Usually LAN links computers within a limited geographical area because they must be connected by a cable, which is quite expensive. People working in LAN get more capabilities in data processing, work processing and other information exchange compared to stand-alone computers. Because of this information exchange most of the business and government organisations are using LAN.
Major Characteristics of LAN
every computer has the potential to communicate with any other computers of the network
high degree of interconnection between computers
easy physical connection of computers in a network
inexpensive medium of data transmission
high data transmission rate
Advantages
The reliability of network is high because the failure of one computer in the network does not effect the functioning for other computers.
Addition of new computer to network is easy.
High rate of data transmission is possible.
Peripheral devices like magnetic disk and printer can be shared by other computers.
Disadvantages
If the communication line fails, the entire network system breaks down.
Use of LAN
Followings are the major areas where LAN is normally used
File transfers and Access
Word and text processing
Electronic message handling
Remote database access
Personal computing
Digital voice transmission and storage
4.4.2 Wide Area Network
The term Wide Area Network (WAN) is used to describe a computer network spanning a regional, national or global area. For example, for a large company the head quarters might be at Delhi and regional branches at Bombay, Madras, Bangalore and Calcutta. Here regional centers are connected to head quarters through WAN. The distance between computers connected to WAN is larger. Therefore the transmission medium used are normally telephone lines, microwaves and satellite links.
4.4.3 Characteristics of WAN
Followings are the major characteristics of WAN.
Communication Facility: For a big company spanning over different parts of the country the employees can save long distance phone calls and it overcomes the time lag in overseas communications. Computer conferencing is another use of WAN where users communicate with each other through their computer system.
Remote Data Entry: Remote data entry is possible in WAN. It means sitting at any location you can enter data, update data and query other information of any computer attached to the WAN but located in other cities. For example, suppose you are sitting at Madras and want to see some data of a computer located at Delhi, you can do it through WAN.
Centralised Information: In modern computerised environment you will find that big organisations go for centralised data storage. This means if the organisation is spread over many cities, they keep their important business data in a single place. As the data are generated at different sites, WAN permits collection of this data from different sites and save at a single site.
4.4.4 Examples of WAN
Ethernet: Ethernet developed by Xerox Corporation is a famous example of WAN. This network uses coaxial cables for data transmission. Special integrated circuit chips called
There are many different types of networks that range in size and proximity. Most can be categorized into one of two basic groups: local area networks (LAN) and wide area networks (WAN).
A local area network (LAN) is a group of networked computers, printers, or other hardware devices that are all connected relatively close to each other like an office, home, or school. It allows connected users to share files, printers, or other applications. Whether as small as two computers or much larger in size, a LAN's major purpose is to allow users to share information quickly and easily.
A wide area network (WAN) is a group of networked computers in a much larger geographical area, such as a state or country. The best example of a WAN is the Internet, which spans the entire world. A router connects your personal LAN to the WAN using a type of networking protocol called TCP/IP. Learn more about client and protocol.
LANs and WANs
There are two types of network: LAN and WAN.
A LAN is a Local Area Network covering a small area such as one building e.g. in a school or a college.
A WAN is a Wide Area Network covering a large geographical area.
