Type of Computer Network

  There are three type of Computer Network :--

         1. Local Area Network ( LAN)

         2. Metropolitan Area Network ( MAN) 

         3. Wide Area Network (WAN)

1. Local Area Network (LAN) :---

                         Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it is also able to access data and
devices anywhere on the LAN. This means that many users can share expensive devices, such as laser
printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or
engaging in chat sessions.  

The following characteristics differentiate one LAN from another:
* Topology
 The geometric arrangement of devices on the network. For example, devices
can be arranged in a ring or in a straight line.

 The rules and encoding specifications for sending data. The protocols also determine
whether the network uses a peer-to-peer or client/server architecture.

 Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables. Some networks do without connecting media altogether, communicating instead via radio waves.

LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN. 

2. Metropolitan Area Network (MAN) : --- 

             Short for Metropolitan Area Network, a data network designed for a town or city. In terms of geographic breadth, MANs are larger than local-area networks (LANs), but smaller than wide-area networks (WANs). MANs are usually characterized by very high-speed connections using fiber optical cable or other digital media. 

3. Wide Area Network ( WAN) :----

A computer network that spans a relatively large geographical area. Typically, a WAN consists of two or more local-area networks (LANs).

Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet.

The shape of a local-area network (LAN) or other communications system. There are three principal 3 topologies used in LANs.

· Bus topology
All devices are connected to a central cable, called the bus or backbone. Bus networks
are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology.

· Ring topology
 All devices are connected to one another in the shape of a closed loop, so that each
device is connected directly to two other devices, one on either side of it. Ring topologies are relatively expensive and difficult to install, but they offer high bandwidth and can span large distances.

· Star topology
 All devices are connected to a central hub. Star networks are relatively easy to install
and manage, but bottlenecks can occur because all data must pass through the hub.
These topologies can also be mixed. For example, a bus-star network consists of a high-bandwidth bus, called the backbone, which connects a collection of slower-bandwidth star segments

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