1. Introduction to
Internet
WWW User
School of Computer Science
2007-2008
2. 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
3. What is Internet?
• Computer network (network of networks)
• Machines and networks using different
technologies
• TCP/IP as communication protocol
4. Some figures
541,677,360
Jan 2008 (http://isc.org/ops/ds)
8. 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
9. 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 at
http://www.tdx.cecsa.es/TDX-1104104-101718
10. Some important people
• Leonard Kleinrock:
• Ray Tomlinson:
• Doug Englebart:
• Vinton Cerf:
• Tim Berners-Lee
• Marc Andreesen:
what did they?
11. 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
12. A network of networks
local host
TCP/IP
gateway
152.6.98.211
remote host
13. Hosts
• Any computer connected to Internet
• Capable of executing user final tasks
• 2 points of view
• locale: executes user programs
• remote: provides services
14. IP Addresses
• IP protocol needs an unique number for
each machine (IP address)
• 4 numbers between 0 and 255
158.42.9.125 (IPv4) … IPv6?
• Data is divided into small packages
• Each package is identified by the receiver IP
15. Types
0 1 8 9 31
A Class 0 Net (7 bits) Local (24 bits)
0 1 2 15 16 31
B Class 10 Net (14 bits) Local (16 bits)
0 2 3 0 0 31
C Class 110 Net (21 bits) Net (8 bits)
0 0 0 31
D Class 1110 Broadcast address (28 bits)
16. 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
17. 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
18. 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
19. TCP/IP Protocol
Transfer Control Protocol (TCP):
Guarantees comm. without errors
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
Internet Protocol (IP):
Isolates users from network media an topologies
