TYPES OF NETWORK Based upon the geographical distribution

TYPES OF NETWORK

Based upon the geographical distribution of computers connected to a network there are mainly three types of network. � Local Area Network (LAN) � Metropolitan Area Network (MAN) � Wide Area Network (WAN)

Local Area Network (LAN) A Local Area Network (LAN) is a group of interconnected computers, printers and other devices that are situated within a radius of 1 km and normally they belong to a single organisation. The following are the salient features of a LAN: 1) LAN is limited by distance. 2) The rate at which data is transferred between two computers in the network is very high. 3) Cables are used as primary medium of data transmission. 4) The users share hardware as well as software resources through LAN.

Metropolitan Area Network (MAN) A Metropolitan Area Network (MAN) is a data network that interconnects the users with computer resources, usually with a spread of a town or a city, using fiber-optical cable or other digital media. The following are the features of MANs: 1) The connections between computers are through the local telephone network. 2) Usually a dedicated leased line is provided by the telephone company to each user, so that, no one else can make unauthorised use of the network. 3) The network size remains between LAN and MAN. 4) Unlike LAN, a MAN is not generally owned by a single organisation. It may be owned by either a consortium of users or a single network service provider who sells the services to the users.

Wide Area Network (WAN) is the largest computer network to which the computers, located across all over the world, are connected. The computers connected to WAN are often connected through public network system such as telephone system. The most popular and largest WAN is the internet. There are two types of WAN: 1) Private WANs and 2) Public WANs.

Private WAN: A private WAN is formed by inter-linking two or more LANs of an organisation. Private WANs are maintained by some big organisations like State Bank Of India (SBI) and Indian Railway maintain their private WAN. Public WAN: Public WANs are not owned by any organisation. Anyone can get connected to public WAN with the help of different technologies. While connected to a public WAN the organisation’s LAN is prone to security threats. 1) Only authorised persons have access to organisations network (say intranet) 2)The messages and attachments entering into the organisations network are scanned for viruses and files with suspected viruses and deleted, and 3) Any access to potentially harmful web sites are denied.

Difference Between LAN and WAN Local Area Network (LAN) Wide Area Network (WAN) Definition A LAN is a computer network that interconnects computers and other communication devices situated in a small geographical area. E. g. -school. A WAN is a computer network that covers a very wide area across the globe. It is formed by interconnecting two or more LANs and MANs. Ownership LAN is owned, controlled and managed by a single organisation or person. WANs are not owned by any organisation. They are characterized by collective or distributed ownership and management. Data Transmission Speed LANs have a very high rate of data transmission. WANs have a lower rate of data transmission then LANs. Data Transmission Error LANS experience very low rate of data transmission error. WANs experience a very high rate of data transmission errors then LANs. Cost LANs cover a smaller geographical area and the number of computers connected to it not as huge as WAN and therefore cost of settling up and maintaining LAN is relatively lower. WAN covers a wider geographical area and the number of computers attached and the communication devices required makes its setting up and maintenance, a costly affair. BASICS