Jan 15, 2013

COMPUTER NETWORKS

COMPUTER NETWORKS 
A computer network is a collection of computers terminal devices connected together by a communication system. The set of computers may include large-scale computers, medium-scale computers, mini computers and microprocessors.

The set of terminal devices may include intelligent terminals, "dumb" terminals, work stations of various kind and miscellaneous devices. 


FEATURES

1. Share resources from one computer to another.
Computer  Networks
2. Create files and store them in one computer,access those files from the other computers connected over the network.
3. Connect a printer,scanner or a fax machine to one computer within the network and let other computers of the network use the machines available over network.

    Following is the list of hardwares required to setup a computer network .............

A>NETWORK CABLES :
Network cables are used to connect computers.the most commonly used cables are category 5 cable RJ-45.

B>DISTRIBUTORS :

Each and every computer can be connected to another one via a serial port but if we need to connect many computers to produce a network, this serial connection will not work.The solution is to use a central body to which other computers,scanners etc.Can be connected and then this body will manage or distribute network traffic.

C>ROUTER :

A router is a type of device which acts as the central point among computers and other devices that are part of a network.a router is equipped with holes called ports.Computers and other devices are connected to a router using network cables.Now a days router comes in wireless modes using which computers can be connected without any physical cable.

D>NETWORK CARD :

Network card is a necessary component of a computer without which a computer cannot be connected over a network.Also known as network adapter or network interface card.Most of branded computers have network card pre-installed.Network cards are of two types internal and external network cards.

                  INTERNAL NETWORK CARDS   

Motherboard has a slot for internal network card where it is to be inserted.Internal network cards are of two types.First type uses peripheral component interconnect(PCI) connection.Second type uses industry standard architecture(ISA).Network cables are required to provide network access. 

                 EXTERNAL NETWORK CARDS    

Comes in two flavour. Wireless and  USB based.Wireless network card need to inserted into the motherboard but no network cable is required to connect to network.USB card are easy to use and connect via USB port.Computer automatically detects USB card and can install the drivers required to support the USB network card automatically.

TYPES OF NETWORKS

There are many types of networks.However,from an end-user's point of view,these are of three basic types.The three basic types of computer networks are as follows .......

1.Local Area Network(LAN)

In this types of network, the different nodes are at most 1KM apart. Generally, LAN is preferred for short distance communication. e.g., between two rooms of the same building or within the same company premises.
Example- Novell Network.

2.Wide Area Network(WAN)

Here, the different nodes are geographically far apart from one another, separating two cities or two states or even two continents. The method of communication in WAN is through logical channels. Actually the origin of WAN was from ARPANET(advanced research project agency network).
Example- Internet.

3.Metropolitan Area Network(MAN)

A metropolitan area network is larger than a LAN. Its features are similar to both LAN and WAN .It is called metropolitan since it normally covers the area of a city.Different hardware and transmission media are often used in MANs because these must efficiently cover the distance(a few tens to about one hundred kilometers) or because these do not require complete access to locations between the network sites.
Example- Cellular Phone,Pager etc.

In addition to these types, the following characteristics are also used to categories different types of network ....


TOPOLOGY

Topology is the geometric arrangement of a computer system. common topologies include a bus,star,ring etc.

PROTOCOL

The protocol defines a common set of rules and signals used by computers on the network to communicate. One of the most popular protocols for LANs is called Ethernet.Another popular LAN protocol for PCs is the IBM tokenring network.

ARCHITECTURE

Networks can be broadly classified as using either peer-to-peer or client/server architecture.Computers on a network are sometimes called nodes.Computers and devices that allocate resources for a network are called servers.

BUS

In computer terminology, a bus is a circuit that carries data from one component to another.




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