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Introduction To Networks

1 - Introduction to networks

Originally, a network was a collection of people or things. Of our network days, we mean business networks, which connect different machines so that they can communicate with each other. Whether for the sharing files or sending messages, most businesses are now equipped with a network in order to be more efficient (it is still more easy to transfer a file over the Internet than to send it on CD by mail).
During this essential we will study how the information (file, data, etc.) circulating on small networks (PAN, LAN) or larger size (MAN, WAN), as well as the connections used.

computer network is a collection of interconnected computers that exchange information. Except that in addition to computers, a network can also contain specialized equipment, like hubs, routers, and many other equipment.
Basically, a network is made up entirely of: IT equipment (computers and network equipment) and point-to-point links that link two equipment together. But all networks are very different from each other. There are many ways to organize the links and computers on a network, thousands of ways to manage the transfer of information over the network.

2. Connect to a network

    * Equipment : 

 computer is made up of various components. Before connecting your computer on a network, it is necessary that you know what makes it up, so that in the event of a failure you can identify whether it is coming from the network or not.

In addition, it will allow you to be more familiar with a machine and can
surely help you in the event of a computer failure.

    * Number systems:

When computers were first created, they were very expensive due to the number of components they required, in addition to their impressive sizes.
A computer could therefore be reduced to a set of electrical switches that can take two states:
On (current is flowing) Off (power is not flowing) For the various tasks they perform today, computers use the binary numbering system.

3- Basic network terminology:

A network is by definition a set of entities communicating with each other. In the course of this course, we will be interested in what are called data networks or computer networks. These networks emerged following a request from companies who were looking for a method to avoid the duplication of printers and a simplification of data communications between computer equipment.
The first network classification that we are going to make is based on the distances between the communicators.

    LAN networks ( Local Area Network ) :

       -LAN networks ( Local Area Network )  allow you to connect the computers of a                  building, or even a site (hence the term (local))

       -  Cover a limited geographic region

       -  Allow multiple access to broadband media

       -  They ensure continuous connectivity to local services (Internet, messaging, etc.)

       -  They physically connect adjacent units

Example: A classroom

    WAN networks (  Metropolitan Area Network ) :

       -  Cover a large geographic area

       - Allow access through slower serial interfaces

       -  Provide connectivity that can be continuous or intermittent

       -  Connect scattered units on a planetary scale

Example: Internet

    MAN (Metropolitan Area Network):

These types of networks are the most common, however there are others, such as MANs (Metropolitan Area Network), which connect one or more LANs in the same geographic region. This type of network is emerging due to the development of wireless networks.

    SAN (Storage Area Network):

SAN (Storage Area Network) is a storage and data transfer area.
     -  Use a different network from the hosts so as not to congest the traffic (this type of                     network generates a lot of traffic).

     - Allow a much higher transfer rate between servers, to allow easier replication or                        movement of data.

     - Allow data to be duplicated between servers up to a distance of 10 km.

     - Use various technologies that allow you to ignore the system used. 

     VPN (Virtual Private Network):

VPN is a private network that is built into a public network infrastructure such as the Internet. Over the Internet, a secure tunnel can be set up between the user's PC and a VPN router located at the company headquarters, so that they can access their own network from home company.