1.2. The Internet and the Web
Internet is a worldwide system of interconnected computer
network, using a standardized set of data transfer protocol. This is a network
of network without nervous center, composed of millions of networks public,
private, academic, commercial and governmental. Internet carries a wide band of
information and allows the development of applications and various services
such as email, instant messaging, and the World Wide Web.
Internet access can be obtained through an Internet Service
Provider through various means of electronic communication, either wired
(telephone network, ADSL, fiber) or wireless (WIMAX, satellite). An Internet
user at that time is designated by the term "surfer".
Internet is constituted of the plurality of networks spread
worldwide and interconnected. Each network is attached to a separate entity
(ISP Internet) and is associated with a unique identifier called Autonomous
System (AS) used by the routing protocol BGP (Border Gateway Protocol). In
order to communicate, network exchange data, either by establishing a direct
link, or by attaching to an exchange node (peering point). These exchanges may
be limited to traffic between their respective users (called peering) or
include third traffic (it is then transit agreement). An operator that provides
Internet transit service to other service providers is called carrier. These
peering are free; they are not subject to regulation by a central authority.
Each network is connected to one or more other networks. When
data is to be transmitted from one computer to another belonging to a different
AS, it is then necessary to determine the way to perform among the networks.
Routers, charge of traffic between the AS usually have a complete routing table
(Full routing table) of more than 330,000 routes in 2010, and send traffic to a
neighbour router closer to the destination after consulting their routing
table.
To access the internet you must have an IP device and a
connection to an ISP. For this, the user uses the following hardware and
software:
· A personal computer or other network terminal
equipment:
- Personal Assistant
- Video-game console
- Mobile phone
· A communication channel to the service provider:
- Fiber Optic
- Fixed telephone line: analog line, ADSL
- Mobile Phone Line:4G , 3G, Edge, GPRS, GSM
- Satellite
- Wi-Fi
· An Internet service provider (ISP)
Software's are required to operate Internet following uses:
· E-mail software: SMTP and POP client or IMAP offered by
Mozilla thunderbird, Microsoft outlook.
· File Transfers software: a client or FTP (File Transfer
Protocol). They may include Filezilla
· World Wide Web: a Web browser
· Peer to peer: one of many P2P software based on use
(sharing peer-to-peer files, Distributed Computing).
Internet operates on a layered model similar to the OSI model.
The elements belonging to the same layers use a communication protocol to
exchange information. A protocol is a set of rules that define a language for
communicating multiple computers. They are defined by open standards.
Each protocol has its own functions and together they provide
a range of ways to respond to the multiplicity and diversity of needs on the
Internet.
The mains are:
ï IP (Internet Protocol) network protocol that defines
the primary mode of exchange between participating computers to the network by
giving them a unique address on the network.
ï TCP (Transfer Control Protocol): responsible for
establishing the connection and control of the transmission. It is a reliable
delivery protocol. This ensures that the recipient has received the data.
ï HTTP (HyperText Transfer Protocol) protocol used for
the loading of web pages.
ï HTTPS (Secured HyperText Transfer Protocol): for HTTP
navigation in secure mode.
ï FTP (File Transfer Protocol): protocol used to transfer
files over the Internet.
ï SMTP (Simple Mail Transfer Protocol) mode of exchange
of e-mail sent.
ï POP3 (Post Office Protocol version 3): mode of exchange
of e-mail reception.
ï IMAP (Internet Message Access Protocol): another email
exchange mode.
ï IRC (Internet Relay Chat): instant chat protocol.
ï NNTP (Network News Transfer Protocol) message transfer
protocol used by Usenet discussion forums
ï SSL (Secure Pocket Layer) or TLS (Transport Layer
Security): secure transaction protocols, used in particular for secure online
payment.
ï UDP (User Datagram Protocol): to communicate,
unreliable but lightly in small datagrams.
ï DNS (Domain Name System): Internet name resolution
system.
ï ICMP (Internet Control Message Protocol): IP control
protocol.
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