2. Lecture 20: Internet Intro to IT COSC1078 Introduction to Information Technology Lecture 20 Internet James Harland james.harland@rmit.edu.au

3. Lecture 20: Internet Intro to IT COSC1078 Introduction to Information Technology Lecture 20 Internet James Harland james.harland@rmit.edu.au

4. Lecture 20: InternetIntro to IT Introduction James Harland Email: james.harland@rmit.edu.au URL: www.cs.rmit.edu.au/~jah Phone: 9925 2045 Office: 14.10.1 Consultation: Mon 4.30-5.30, Thu 11.30-12.30 Who am I? And where do you find me?

5. Lecture 20: InternetIntro to IT Introduction to IT 1 Introduction 2 Images 3 Audio 4 Video WebLearnTest 1 5 Binary Representation Assignment 1 6 Data Storage 7 Machine Processing 8 Operating Systems WebLearn Test 2 9 Processes Assignment 2 10 Internet 11 Internet Security WebLearn Test 3 12 Future of ITAssignment 3, Peer and Self Assessment

6. Lecture 20: InternetIntro to IT Overview  Questions?  Assignment 3  Peer and Self Assessment  Internet  Questions?

7. Lecture 20: InternetIntro to IT Assignment 2  Some initial comments Some people have submitted.docx files. This will be penalised. Some people have not included blogs on Blackboard. This will be penalised. Some people have worked individually without permission. Guess what will happen ….

8. Lecture 20: InternetIntro to IT Assignment 3  Reflect Answer reflection questions from tutorials See last lecture for ideas  Research Write about a particular IT topic of your choice (5- 6 paragraphs) electronic voting, information security, 3D user interfaces, digital music, digital video, electronic commerce, natural language processing, DNA computing, quantum computing, cryptography, malware detection and removal, Moore's Law, green computing, …

9. Lecture 20: InternetSE Fundamentals Self and Peer Assessment  How well has each person contributed to the group?  Evaluated over the entire semester  Assessed on process, not product  Work out a grade for each person (CR, DI etc)  Then convert this to a mark out of 20  Submit list of marks to tutor with justifications  Repeat previous step until the tutor is satisfied  See guidelines in Blackboard material

10. Lecture 20: InternetIntro to IT Communications Developments  ????: Writing  1440: Printing press  1844: Telegraph  1877: Telephone  1919: Radio  1928: Television  1969: ARPANET (Advanced Research Projects Agency)  1970's: Internet Protocol (IP)  1984: Domain names (.com,.org, etc)  1991: World Wide Web

12. Lecture 20: Internet: ImagesIntro to IT Number of Internet Hosts

13. Internet  Originally designed to survive nuclear war  Grew out of army research into missile communication  Key role in breaking down the Berlin Wall Lecture 20: InternetIntro to IT

15. Lecture 20: InternetIntro to IT Internet  Dedicated channel: two nodes exclusively use a single channel works like traditional telephone  Packet switching: break data down into packets send packets from many users along link can exploit redundancies and variations in network

16. Lecture 20: InternetIntro to IT Protocols  Transmission Control Protocol (TCP): basic necessities for data transfer connection-oriented  Internet Protocol (IP): data-oriented necessary for packet-switched network “Should run on two tin cans and a string” There is an implementation for carrier pigeons...

17. Lecture 20: InternetIntro to IT Protocols

18. Lecture 20: InternetIntro to IT Application Protocols  Define messages sent and data formats used  Generally known by user  Examples include HTTP, HTTPS, FTP, etc. Often specified in resource identifiers http://www.mysite.com:8080/info/mypage.html

19. Lecture 20: InternetIntro to IT World Wide Web (WWW)  Combination of 4 different ideas:  Hypertext: information format for moving documents around  Markup Language: codes embedded in text indicating structure and presentation meaning  Resource Identifiers (URI, URL,...)  Client-server model: client software requests resources from servers  Note WWW is not the Internet …

20. Lecture 20: InternetIntro to IT Internet Uses  File transfer & remote services  Email  Instant messaging  Web browsing  Peer to peer (P2P)  Telephony  Streaming media  “Web 2.0” ....

21. Lecture 19: Internet: ImagesIntro to IT Internet Lisa? Hi Dad! Listen! Lisa? Hi Dad! Listen!

22. Lecture 20: InternetIntro to IT Internet Structure Application Transport Network Link Network Link Mordor sucks! 2 dor1 Mor 3 suc4 ks! 1 2 3 4 956 2 1 4 3 2 2 1 3 4 2 3 1 4 956 2 2 dor1 Mor 3 suc4 ks! Mordor sucks!

23. Lecture 20: InternetIntro to IT Internet Structure 1 Mor 1 6 6

24. Lecture 20: InternetIntro to IT Network Layer (Internet Protocol)  Real intelligence is in the network layer  Adds next destination to packet  Not complete list of addresses  Sends to next destination  Retrieves final destination packets for this node  Passes them to the transport layer  Routing tables can be updated when disconnections occur  Hop counts used to stop endless looping

26. Lecture 20: InternetIntro to IT Transport layer  Transmission Control Protocol (TCP) often used  User Datagram Protocol (UDP) becoming more common  TCP Establishes connection first Send and wait for acknowledgement Reliable Can adjust flow control to avoid congestion Often best for email (which is not real-time) Older

27. Lecture 20: InternetIntro to IT Transport layer  UDP Doesn’t establish connection Just sends and forget Efficient No congestion adjustment Works well for DNS lookup Often used for Voice over Internet Protocol (VoIP) applications such as Skype

28. Lecture 20: InternetIntro to IT Internet addresses  Unique 32-bit identifier (up to 4,294,967,296)  Soon to become 128-bit identifier  Managed by Internet Corporation for Assigned Names and Numbers (ICANN)  ISPs get “blocks” of addresses  32-bit string represented as N 1.N 2.N 3.N 4 where N i is in the range 0..255  17.12.25.0 means 00010001 00001100 00011001 00000000

29. Lecture 20: InternetIntro to IT Internet addresses  Dotted decimal notation is still not very kind to humans …  www.sludgefacethemovie.com -> ??.??.??.??  Translation done by name servers which look up the Domain Name System (DNS)  Domains such as rmit.edu.au can be structured by the domain owner (eg goanna.cs.rmit.edu.au)

30. Lecture 20: InternetIntro to IT IPv4 vs IPv6  Internet Protocol version 4 (used since 1981)  32-bit addresses  Can handle “only’’ 4,294,967,296 unique addresses  Exhausted in February 2011  IPv6 uses 128-bit addresses  IPv6 can handle “only” 3.4×10 38 addresses  IPv5 didn’t change the IPv4 address space and wasn’t successful for other reasons …

31. Lecture 20: InternetIntro to IT Conclusion  Work on Assignment 3  Name 5 people who are unaffected by the Internet …