Introduction to Internet

Introduction to Internet

WWW UserSchool of Computer Science

2007-2008

Aims

• Knowing Internet fundamentals

• Selecting the most important milestones

• Identifying the most important people and their contributions

• Enumerating the most usual protocols

• Identifying the basic services

What is Internet?

• Computer network (network of networks)

• Machines and networks using different technologies

• TCP/IP as communication protocol

Some figures

541,677,360

Jan 2008 (http://isc.org/ops/ds)

Internet evolution (1991)

Internet evolution (1991-1997)

Internet evolution (1997)

Initial goals (“officials”)

• To avoid any center. Each one manages its own networks

• Keep the network simple. Complex tasks done in nodes

• Implemented in any media and topology

To know more...

Andreu Veà i Baró: Historia, Sociedad Tecnología y Crecimiento de la Red. Una aproximación divulgativa a la realidad más desconocida de Internet.- PhD. Thesis

Available athttp://www.tdx.cecsa.es/TDX-1104104-101718

Some important people

• Leonard Kleinrock:

• Ray Tomlinson:

• Doug Englebart:

• Vinton Cerf:

• Tim Berners-Lee

• Marc Andreesen:

what did they?

Management Org.

• ISOC (www.isoc.org)Internet Society: standarisation and promotion

• IETF (www.ietf.org)The Internet Engineering Task Force: Internet evolution

• IAB (www.iab.org)Internet Architecture Board

• INTERNIC (www.internic.net)Domain registration

A network of networks

local host

remote host

gateway

152.6.98.211

TCP/IP

Hosts

• Any computer connected to Internet

• Capable of executing user final tasks

• 2 points of view

• locale: executes user programs

• remote: provides services

IP Addresses

• IP protocol needs an unique number for each machine (IP address)

• 4 numbers between 0 and 255158.42.9.125 (IPv4) … IPv6?

• Data is divided into small packages

• Each package is identified by the receiver IP

Types

A Class

B Class

C Class

D Class

0 Net (7 bits) Local (24 bits)

10 Net (14 bits) Local (16 bits)

110

1110 Broadcast address (28 bits)

Net (21 bits) Net (8 bits)

0

0

0

0

1 8 9 31

1 2 15 16 31

2 3 0 0 31

0 0 31

IP Ranges

Class Code Net Local From To Networks / hosts

A 0 7 24 0.1.0.0 126.0.0.0 126 / 16,000,000

B 10 14 16 128.0.0.0 191.255.0.0 16,000 / 65,000

C 110 21 8 192.0.0.0 223.255.255.0 2,000,000 / 254

D 1110 224.0.0.0 239.255.255.255 General diffusion

IPv6

• It uses 128 bits →2128 = 3.4 x 1038

• that means 0.6 x 1025 address / cm2

• there’re 1051 atoms in the Earth

• 8 groups of 4 hexadecimal digits

2001:0db8:85a3:08d3:1319:8a2e:0370:7334

Domain Name Server (DNS)

• use mnemonics ‘machine.domain’

• IP and name registered together

• security: avoid duplicates

• confort: routing tables

• Name Server: program that translates addresses from textual to numeric

TCP/IP ProtocolTransfer Control Protocol (TCP): Guarantees comm. without errors

Internet Protocol (IP): Isolates users from network media an topologies

Emissor • Divides data into packages and numbers them

Receiver • Orders received packages and composes the original message.

• If some package is missed, ask for it to be resended

Application Layer

Transport Layer

Internet Layer

Physical Layer

TCP/IP family

DNS

SMTP

TELNET

RPC

FTP

HTTP

TCP UDP

IP ICMP