Introduction to Internet
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  • 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)
  • 5. Internet evolution (1991)
  • 6. Internet evolution (1991-1997)
  • 7. Internet evolution (1997)
  • 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
  • 20. TCP/IP family Application Layer FTP TELNET DNS SMTP RPC HTTP Transport Layer TCP UDP Internet Layer IP ICMP Physical Layer