Lecture 20: Internet Intro to IT

COSC1078 Introduction to Information Technology

Lecture 20

InternetJames Harland

james.harland@rmit.edu.au

Lecture 20: Internet Intro to IT

COSC1078 Introduction to Information Technology

Lecture 20

InternetJames Harland

james.harland@rmit.edu.au

Lecture 20: Internet Intro 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 11.30-12.30Who am I? And where do

you find me?

Lecture 20: Internet Intro to IT

Introduction to IT1 Introduction 2 Images3 Audio4 Video WebLearnTest 1 5 Binary Representation Assignment 16 Data Storage7 Machine Processing8 Operating Systems WebLearn Test 29 Processes Assignment 210 Internet11 Internet Security   WebLearn Test 312 Future of IT Assignment 3, Peer and Self Assessment

Lecture 20: Internet Intro to IT

Overview Questions?

Assignment 3

Peer and Self Assessment

Internet

Questions?

Lecture 20: Internet Intro 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 ….

Lecture 20: Internet Intro to IT

Assignment 3 Reflect

Answer reflection questions from tutorialsSee last lecture for ideas

ResearchWrite 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, …

Lecture 20: Internet SE 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

Lecture 20: Internet Intro 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

Lecture 20: Internet: Images Intro to IT

Number of Internet Hosts

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

0

100000

200000

300000

400000

500000

600000

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: Internet Intro to IT

Lecture 20: Internet Intro to IT

Internet Dedicated channel:

two nodes exclusively use a single channel works like traditional telephone

Packet switching: break data down into packetssend packets from many users along linkcan exploit redundancies and variations in network

Lecture 20: Internet Intro to IT

Protocols Transmission Control Protocol (TCP):

basic necessities for data transferconnection-oriented

Internet Protocol (IP): data-orientednecessary for packet-switched network

“Should run on two tin cans and a string”There is an implementation for carrier pigeons ...

Lecture 20: Internet Intro to IT

Protocols

Lecture 20: Internet Intro 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 identifiershttp://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.htmlhttp://www.mysite.com:8080/info/mypage.html

Lecture 20: Internet Intro 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 …

Lecture 20: Internet Intro to IT

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

Lecture 19: Internet: Images Intro to IT

Internet Lisa?Hi Dad! Listen!Lisa?

Hi Dad! Listen!

Lecture 20: Internet Intro to IT

Internet Structure

Application Application

Transport Transport

Network

Link

Network

Link

Mordor sucks!

2 dor1 Mor3 suc 4 ks!

1 2 3 49 5 6 2

143

22

13

4

2 3 1 49 5 6 2

2 dor1 Mor3 suc 4 ks!

Mordor sucks!

Lecture 20: Internet Intro to IT

Internet Structure

1 Mor

1

6

6

Lecture 20: Internet Intro 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

Lecture 20: Internet Intro to IT

Transport layer Transmission Control Protocol (TCP) often used User Datagram Protocol (UDP) becoming more

common TCP

Establishes connection firstSend and wait for acknowledgementReliableCan adjust flow control to avoid congestionOften best for email (which is not real-time)Older

Lecture 20: Internet Intro to IT

Transport layer UDP

Doesn’t establish connectionJust sends and forgetEfficientNo congestion adjustmentWorks well for DNS lookupOften used for Voice over Internet Protocol (VoIP) applications such as Skype

Lecture 20: Internet Intro 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 N1.N2.N3.N4 where Ni

is in the range 0..255 17.12.25.0 means00010001 00001100 00011001 00000000

Lecture 20: Internet Intro 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)

Lecture 20: Internet Intro 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” 3.4×1038 addresses IPv5 didn’t change the IPv4 address space

and wasn’t successful for other reasons …

Lecture 20: Internet Intro to IT

Conclusion

Work on Assignment 3

Name 5 people who are unaffected by the Internet …