topic 11
The Internet & WWW
the Internet
• worldwide connection of thousands of computer networks.
• these networks use a common language to communicate.
• transmission Control Protocol/Internet Protocol (TCP/IP)
– enables instantaneous transmission/reception of digital data
• the Internet is a cooperative community of networks.
• no particular body owns the internet.
the network
• the Internet is structured in an ‘hierarchical form’.
• more than 500,000 networks in more than 150 countries.
bandwidth
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communication channels carry data on the Internet backbone
bandwidth- is a channel’s data carrying capacity.
bandwidth =
no. of bits of information passed/second
different Internet channels
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phone Lines (twisted pair)
coaxial cable
fibre Optics
microwave
satellite
http://www.southerncrosscables.com/media/user/images/submarinegraphic.jpg
http://www.southerncrosscables.com/media/user/images/submarinegraphic.jpg
fibre-optic cable
the Internet in Australia
• Australian telecommunication agencies carry internet traffic on
the Telstra backbone
• Internet provided and maintained by Telstra Internet Direct
• Telstra’s domestic internet capacity
– 1997 100Mbps
– 1999 1,000Mbps
– 2004 10,000Mbps
broadband connectivity
- fibre optic
- satellite
- microwave
devices
tcp/ip
• TCP/IP
– data transmission protocol on which Internet is based.
– breaks Internet data into small ‘Information Packets’.
– each packet contains the data and the address where it is
being sent.
• Routers
– computers routing ‘Information Packets’ through channels
to destinations.
• TCP/IP
– keeps records of original data for rearranging packets in
correct order on arrival at destination.
internet traffic
Internet addresses
• IP address
• each computer on the Internet has a unique IP number.
• it consists of ‘4 bytes’, numbers ‘0 and 255’, separated by
periods
• eg- 139.230.169.149
email
• e-mail is electronic transmission and reception of messages
between users on the Internet.
• each user has a unique ‘e-mail’ address.
– eg- john@hotmail.com
– where ‘john’ is username, ‘hotmail.com’ is the domain.
• an e-mail consists of
– ‘Title:’ or ‘To:’
– ‘Body’
– ‘Signature’
peer 2 peer
• two (or more) computers linked directly to each other
via their IP numbers
• allows real-time communication between machines
• some systems use servers to identify machines on
the network
• examples:
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ICQ
CU-SeeMe
MSN Messager
Skype (voice over IP)
voice over IP
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voice messages sent as packets over the Internet
computer to computer
computer to phone
operates on local area networks
many extra services
videoconferencing
• enables people to see and speak
• previously required dedicated lines
• bandwidth hungry
remote control
• Internet used to control devices remotely
World Wide Web
• most commonly used method of accessing
information the internet
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sound
graphics
animation
interactivity
a browser
tracking
assignment submission
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5 MB limit
all files in one folder
create archive of the folder
upload to SCAM syte to tutor
only 1 upload possible, upload to spare is a problem
arises
• keep a copy in case!!
exam
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covering lecture content
2 hours + 5 mins reading
20 multi-guess (10 marks)
20 short answer (20 marks)
– brief responses and point form is encouraged