Wednesday, 23 May 2012


LAN (Local Area Network):
Uses and Advantages of LAN:-
MAN (Metropolitan-Area Network): 
WAN (wide area network):
LAN is the most common type of network. LAN stands for Local Area Network. It covers a small area. Most LANs are used to connect computers in a single building, campus, office or room etc. Hundreds or thousands of computers may be connected through LAN. There are marty types of LANs. Ethernet is the most common for PCs.
The above figure shows a LAN. All computers are connected to a central node in star topology. The central node is a special device called a network hub. All links are made up of UTP cables. The maximum recommended length of a UTP connection in LAN is 100 meters. No computer should be more than 100 meters away from hub.
All computers in LAN can communicate with each other at a high speed. The speed of communications between any two devices on an Ethernet LAN can be 2 to 1000 millions bits per second (Mbps). LAN can transmit data in a limited distance.

• One copy of a software can be shared by all users in a LAN
• System resources such as printers can be shared between several people in network.
• It is easy to manage the data stored on a centralized computer in the network.
• The data is more secure from being copied or destroyed.
• Data can be shared by all users using the network.

A metropolitan area network (MAN) is a communications network that covers a geographical area of the size of a city. A MAN typically include one or more LANs but cover a small geographical area than WAN. A MAN often acts as a high-speed network. Mobile phones systems often use MAN.

WAN stands for wide area network. It refers to a network that covers a large area. WAN connects computers in different cities and countries. Computers in WAN are often connected through telephone lines. They can also be connected through leased lines or satellites. WAN can reach the parts of the world that is not possible with LANs.
The mainframe and- minicomputers used in WAN are designed to be accessed by terminals. A personal computer must appear as a terminal to communicate with large computers in WAN. Tetminai emulation software is usedlo allow a personal computer to appearas In this-way the personal computer can connect to a large computer.
The larger computer is known as host computer. A personal computer attached to host computer can upload and download data. The transfer of data from personal computer to host computer is known as uploading. The transfer of data from host computer to personal computer is known as downloading. File transfer soffware is used to do upload and download data.
Transmission rate of WAN is typically 56kbps to 45Mbps. WAN is not as fast as LAN.
It requires long cable distances and there is a possibility of error in data transmission.