There are many types of computer networks from personal area networks and metropolitan area networks through to virtual private networks. This simple guide gives an overview of what these types of networks are and some of the technologies behind them.

Personal Area Network (PAN)

A Personal Area Network or simply PAN, is smallest network which is very personal to a user. This may include Bluetooth enabled devices or infra-red enabled devices. PAN has connectivity range up to 10 meters. PAN may include wireless computer keyboard and mouse, Bluetooth enabled headphones, wireless printers and TV remotes for examples.

Local Area Network (LAN)

A computer network spanned inside a building and operated under single administrative system is generally termed as Local Area Network. Usually, Local Area Networks cover an organization such as offices, schools, college/universities etc. The number of systems connected to a local area network may vary from as few as two to as many as 16 million.

A LAN provides a useful way of sharing resources between end users. Resources like Printers, File Servers, Scanners and internet are easily shareable among computers.

Local Area Networks are composed of inexpensive networking and routing equipment. They may contains local servers serving file storage and other locally shared applications. They mostly operates on private IP addresses and generally do not involve heavy routing.

LANs usually use Ethernet technology. The data transfer rate in a local area network is of the order of 10 to 100 mega bits per second( Mbps).

Metropolitan Area Network (MAN)

A metropolitan area network generally expands throughout a city such as cable TV network. It can be in form of Ethernet, Token-ring, ATM or FDDI. Metro Ethernet is a service which is provided by ISPs. This service enables its users to expand their Local Area Networks. For example, MAN can help an organization to connect all of its offices in a City.

The backbone of a MAN is high-capacity and high-speed fiber optics. A MAN works in between Local Area Networks and Wide Area Networks. MANs provides uplink for LANs to WANs or the Internet.

Wide Area Network (WAN)

As its name suggests, this network covers a wide area which may span across provinces and even a whole country. Generally, telecommunication networks are Wide Area Networks. These networks provides connectivity to MANs and LANs. Equipped with very high speed backbone, WANs uses very expensive network equipment. WANs may also use advanced technologies like Asynchronous Transfer Mode (ATM), Frame Relay and SONET. WANs may be managed under by more than one administration.

Virtual Private Network (VPN)

A VPN is a network that is constructed by using public wires (usually the Internet) to connect to a private network, such as a company›s internal network. There are a number of systems that enable you to create networks using the Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.

The Internet

A network of networks is called an internetwork, or simply the Internet. It is the largest network in existence on this planet. The Internet connects all WANs and it can have connection to LANs and home networks. The Internet uses the TCP/IP protocol suite and uses IP as its addressing protocol. At the time of writing, the Internet is widely implemented using IPv4. Because of shortage of address spaces, it is gradually migrating from IPv4 to IPv6.

The Internet enables its users to share and access enormous amount of information worldwide. It uses www, ftp, email services, audio and video streaming etc. At a macro level, the internet works on the Client- Server model. The Internet uses very high speed backbone of fiber optics. To inter-connect various continents, fibers are laid under sea known to us as submarine communication cable.