A computer network is a telecommunication network that allows computers to exchange data. The physical connection between networked computing devices is established using either cable media or wireless media.

Network devices that originate, route and terminate the data are called network nodes. Nodes can include hosts such as servers and personal computers, as well as networking hardware. Two devices are said to be networked when a process in one device is able to exchange information with a process in another device.

Types Of

Network

pan

Personal area Network

A Personal Area Network or PAN is a computer network used for communication among various electronic devices such as personal computers, mobile phones in a close proximity. The area of a PAN is typically a few meters. PANs can be used for communication among the devices or for connecting to the Internet. A PAN may use wireless connection as well.

Local Area Network

A Local Area Network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media. It is the most common type of network. Usually, local area network has not more than 100 computers.

man

Metropolitan Area Network

A Metropolitan Area Network (MAN) is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network but smaller than the area covered by a wide area network. The term is applied to the interconnection of networks in a city into a single larger network.

Wide Area Network

A Wide Area Network (WAN) is a network that covers a broad area using private or public network transports. It connects local and metropolitan area networks together. The networks that make up a wide area network, may be located throughout a country or even around the world.

CAN

Campus Area Network

Campus Area Networks are usually a connection of many small LAN networks which are often used on university campuses and office buildings. Campus Area Networks allow for easy file sharing between different departments as all the files are usually shared on the server machines of each LAN network. This type of network offers a lot of simplicity in the transfer and downloading of files.

The network stores most of the information on a central computer. Storing information on one or two central computers makes it easy for people to work with and manage their files.A network also allows people to access their information from other computers on the network.

The network has dedicated computers that allow people to connect to the company’s network using a modem.Once users are connected to the network, they can work with any data available on the network. Network makes it easy for people to access office information from home.

Computers connected to a network can share equipments and devices including printers and hard drives. These equipments and devices are called resources. The ability to share resources reduces the cost of buying computer hardware. For example, instead of buying a printer for each person on network, everyone on the network can share one central printer.

You can use a network to exchange information with other people. Information can be in any form of data, such as documents created in a word processing program, information provided by a school database.

Using computers connected to a network people exchange information with one another. When employees can easily access and exchange information, they can work more efficiently. For example, network allows people in different offices to work on a project together.

Most of the people who are connected to a network, use a central computer to work with different programs such as word processors and spreadsheets. Network makes installing programs simple because only one copy of a program needs to be installed on a central computer.

Network hardware includes the physical components that are used to create a network. All computer networks require at least the following network hardware :-

A connector is a device that joins two computers on network together.

Cables are the wires that connect computers and resources on a network. Different kinds of cables can be used, depending on the type and size of the network.

A Network Interface Card (NIC) is a device that joins a cable to a computer. Most NICs are installed inside a computer. The edge of the card can be seen at the back of the computer. A NIC has a port where the network cable plugs in.

The most important job of a network is to link computers together. When computers are linked, the people using the computer can work more efficiently.

Data security concernsA poorly secured network puts critical data at

risk. For example: When files are shared among user then there is always a threat that unauthorized users can alter of use the sensitive data.

Network Implementati

on costTo setup a network requires investment in hardware and software. For small network of few PCs this cost is smaller but for large network this cost can run in thousands or more

Threat from virusesThe effect of viruses on a network is more

as compared with stand- alone systems because viruses can easily spread one computer to another over networks

A protocol is a set of rules that governs the communications between computers on a network. These rules include guidelines that regulate the following characteristics of a network: access method, allowed physical topologies, types of cabling, and speed of data transfer.

Internet Protocol (IP) is the protocol by which data is sent from one computer to another on the Internet. Each computer on the Internet has at least one IP address that uniquely identifies it from all other computers on the Internet. When you send or receive data, the message gets divided in the form of packets. These packets contain both the sender’s Internet address and the receiver’s address. The Internet Protocol just delivers them.

Topologies define the arrangement of computers taking part in the network. These should be properly planned and implemented because a good selection of topology can result in proper and adequate use of resources while a mismanaged arrangement of computers can lead to inefficient use of resources, loss of data and time.

In a bus topology, all of the nodes are connected to a central cable called bus. In bus topology, a bus is a single continuous cable.Transmission from any node travels the length of the bus in both directions and can be received by all other nodes. The bus has terminators at either ends which absorbs the signal, removing it from the bus.

It is quite easy to set up.Failure of one node does not affect the rest of the network.

It offers limited flexibility for change.A signal on the bus must be strong enough to reach the receiver.

In a ring topology, the nodes are connected in a closed loop so that each device is connected to two others, one on either side.The computers in a ring topology are connected in the shape of a closed ring.Data travels only in one direction in a ring. Each computer passes the data to the next one on the line automatically.

The ring works well where there is no central-site computer system.It is more reliable than a star network.

The ring network requires more complicated control software.Failure of the one node results in the failure of the entire network.

Star topology id the most common type of network topology that is used in homes and offices. In Star Topology, there is a central connection point called the hub. Each computer on a star network communicates with a central hub that resends the message either to all the computers in a broadcast star network or only to the destination computer in a switched star network.

Star topology has minimal line cost.If any of the local computer fails, the remaining portion of the network is unaffected.

The system crucially depends on the central switch. If it fails, the entire network goes down.The cabling cot is more as each node is connected individually to the hub.