Types of Networks [LAN, MAN, WAN] Local area and wide area networks

Types of Networks [LAN, MAN, WAN]

TYPES OF NETWORKS

Networks can be classified as follows:

Local Area Network (LAN)

A LAN is a system of interlinked personal computers in a localized area, typically under 1 km across. LANs normally operate within a compact area such as an office building or a campus owned by the using oranization . 

The  configuration of a LAN can be a star, a ring or simple devices attached along a length of cable. In LAN, transmission channels used are coaxial or fibre optic cable and special interface units  rather than telephone lines and modems. 

Thus the transmission speed is very high. The attached computers may be of different types and be performing a variety of functions such as data processing , word processing and electronic mail.

                There are two main advantages of LAN: One is resource sharing and another is communication.

                Ethernet, developed by Xerox Corporation, is a famous example of a LAN. This network uses coaxial cable for data transmission . Omininet developed  by Corvus System is another example of a LAN. This particular network has the ability to interconnect different microcomputer systems such as Radio stack, Apple.

Wide Area Network (WAN)

When network of computers is spread throughout a nation or in the entire world then such a network is called Wire Area Network. Several LANs are connected to form a WAN. WAN provides communication services to a large geographic area (100’s to 1000’s of kms). Communication on a WAN takes place via telephone lines, satellite or microwave links, rather than through a physical cable.

ARPANET of the Advance Research Project Agency Network of the U.S. Department of Defence is an example of WAN. This network connects about 40 universities and research institutions throughout the United States and Europe with about 50 computers ranging in size from mini to super computers. Another example of a WAN is the INDONET, which is developed by Computer Maintenance Corporation, India (CMC) in 1985. It links three IBM/4361 systems one each at Mumbai, Kolkata and Chennai and a POP 11/44 system at Delhi. It gives nationwide access and Processing facilities.

Metropolitan Area Network (MAN)

In between LAN and WAN is the Metropolitan Area Network (MAN) . A MAN is a network that covers an entire city, but users LAN technology. Cable television networks are example of MANs, distributing television signals. The MANs we are interested in , carry information in the form of computer signals from one computer to another.

DIFFERENCES IN LAN AND WAN

The main differences between LAN and WAN are:

1. A LAN is restricted to a limited geographical coverage of  a few kilometers but a WAN can be spread thrughout a nation or in the entire world.

2.  The cost of transmitting data in LAN is negligible  since the transmission medium is usually owned by the user organization. However in case of WAN, this cost may be very high because the transmission medium  used are leased lines or public systems such as telephone lines, microwaves and satellite llinks.

3.  In LAN, the computers, terminals and peripheral devices are physically connected with wires and coaxial cables. Whereas , in WAN, there may not be direct connection between various computers.

4.  Data Transmission speed is much higher in LAN as compared to WAN. 

Transmission speed in LAN’s are 0.1 to 100 mega bits per second. On the other hand, in a WAN the data transmission speed is normally of the order of 1800 to 9600 bits per second.

                LANs are less error prone as compared to WANs. Since in a LAN, distance covered by data is limited , less error occurs in LAN.

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