1st Session

Caroline De Cock & Peter Van Roste

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Putting thingsin perspective:

what will happenon the Internetduring the next

hour?

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13 billionemails

The amount of emailssent per hour

2100hoursThe amount of YouTubeVideos uploaded every hour

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How is this possible?

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#1. Something started 42 years agofor military & academic purposes

was opened to commercial companies

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#2. And the technology to

make it work was made open

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So what’s

the Internet

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The Internet is a bunch of computers and

cables linked to each other and that can

communicate across the globe

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“

The Internet is the worldwide, publicly accessible network of interconnected computer networks that transmit data by using the standard Internet (IP). It is a "network of networks" that consists of millions of smaller domestic, academic, business, and government networks, which together carry various information and services, such as electronic mail, online chat, file transfer, and the interlinked Web pages and other documents of

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All of this translates into a multitude of players

Source: OECD, The economic and social role ofInternet intermediaries, April 2010

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*Plain Old Telephony Services

From POTS* to the Net

Traditional telephony is based on circuit switching, which implies:

• Communication flow follows a path that is selected beforehand and that remains fixed during the session

• This path is dedicated

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So this is what a circuit switched network looks like

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Packet switching

The Internet is based on packet switching, which implies:

• The sending computer slices data into small packets, with an address on each to tell the network where to send them

• These packets are sent as need be and in what looks like a chaotic flow

• At the end, the receiving computer puts the puzzle back together

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But what’s in a packet?

FooterBody/DataHeader

1000 to 1500 bytes

- Sender &Receiver IP address- Protocol- Packet n°

- Data (e.g. The content of an email)

-Data to show end of packet- Error correction

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So this is what a packet switched network looks like

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Application Layer

And to make all of this work, you need a common language: PROTOCOLS

Transport Layer

Network Layer

Data / Link Layer

Physical Layer

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And to function, these protocols need to go through ports

File transfer Email Web browsing VoIP

FTP SMTP HTTP SIP

Ports20 or 21

Port25

Port80

Transport Layer

Port5060

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...OK but what happens between this

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...and that?

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#1. Find server

#2. Process query

#3. Assembly

#4. Return to PC

62.25.101.80

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Disclaimer

Source: http://909sickle.com/s/geeks-and-nerds/22

Disclaimer (cont’d)

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