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Internet, one view
Internet, another view
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Other views
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Objectives
• Understanding of data communication networks • Logical levels of communication
• Physical
• Network
• Application
• Security on Internet • Search engines
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Course content?
• 11 lectures • 3 mandatory laboratory sessions • Two hand in problem • Home exam
Schedule of lectures (E:2311) Week Date Topic 1 30/10 13-15 Introduction
1 2/11 10-12 Physical layer
2 6/11 13-15 Data link
2 9/11 10-12 Network access
3 13/11 13-15 Wide Area Networks
3 16/11 10-12 Routing
4 20/11 13-15 Applications
4 23/11 10-12 Network management alt. Mobile networks
5 27/11 13-15 Web search
6 4/12 13-15 Network security
7 11/12 13-15 Repetition/Reserve 7
Laboratory exercises (E:)
Study week Topic
5 Protocols
6 World Wide Web --- WWW
7 Infrastructure and applications
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• Two groups per week • Signa up for groups on the web page • Prepare before
Exercises
• Recommended problems can be found on the web page
• Question hours scheduled on the web page • Friday 9/11 13-15 E:3139
• …
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Course material
• Two alternative books (sold by KFS)
• Data Communications and Networking (5 Ed), B.A. Forouzan
• Internet, M. Kihl and J. A. Andersson • Slides published on web page • Lab manual • Exercises
Examination
• Laboratory sessions • Hand in problems
• After study week 2 and 4
• Home exam
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What is Internet?
• How did it start? • What is Internet today? • How does it work?
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Data communication
After torches and smoke signals, the optical telegraph was invented in the 18th century.
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Data communication
Optical telegraphs evolved into electrical telegraphs, which quickly increased the available data communication speed and distance.
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Telephone networks
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The need for telephone networks became obvious in the late 19th century...
Basics of circuit switching
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Telephone networks
17 • Late 1940: 350 000 operators at AT&T, 98% women
Basics of packet switching
18 Source: http://www.tcpipguide.com
Internet growth
• 1969 ARPANET • Advanced Research Projects Agency Network
• First packet switched network
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• UCLA • University of California, Los Angeles
• SRI • Stanford Research Institute
• UCSB • University of California, Santa Barbara
• UTAH • University of Utah
Internet growth
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Internet growth
• 1985 NSFNET replaces ARPANET • Backbone based on 56kb/s links
• 1988 backbone complemented with 1.5Mb/s links • 1991
• upgrade to 44Mb/s
• 600 000 hosts in 100 countries
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Internet growth
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• Map of Internet 2003
• Color coding according to continents
Internet growth
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• Connection density
Connection technology
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Nielsen’s law
The end-user connectivity grows with 50% every year.
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Internet growth
Internet in numbers ≈2015: • 1 billion fixed connections • >7 billion mobile connections • 15 billlion devices (twice the population) • 1 million minutes of video every second • Total traffic close to 1Zbyte/year (Z=zetta=1021)
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Client/server paradigm
Most early applications were based on the client/server paradigm.
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Request
Reply
Telnet
Telnet was invented in 1969, and provided access to a remote terminal.
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TELNET, klient
Terminal driver
Network
TELNET, server
Local computer
Applications
Pseudoterminal driver
• Ray Tomlinson sent the first email in 1971 • To separate a specific user on a host computer, he
used the @ sign. It was unused on the keyboard.
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30 Source: http://www.tekguard.com
File Transfer Protocol (FTP)
• FTP was devloped in 1971 • It enabled file transfer between two computers.
31 Source: http://opcenter.cites.uiuc.edu
Internet protocol
• In 1973, Robert E. Kahn and Vincent Cerf developed the ideas of an internetwork protocol that made it possible for hosts on different networks to communicate with each other.
• The ideas defined the Transmission Control Protocol (TCP) protocol in 1974.
• Later, some parts of the TCP protocol were moved to the Internet protocol (IP), creating the TCP/IP protocol suite.
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Basic idea of Kahn and Cerf’s internetworking
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NetworkNetwork
Network
§ Host identification (Addresses)
§ Forwarding of messages between networks (routing)
§ End-to-end reliability (error and flow control)
In the beginning
• 1978: First spam (by Gary Thuerk) • 1982: Scott Fahlman introduces :-) and :-( • 1985: lth.se registrerades • 1987: GIF • 1988: Internet worm
(by Robert Tappan Morris) • 1990: Internet service provider
(world.std.com) 34 Boston Museum of Science.
World wide web (www)
• 1990: Tim Berners-Lee developed • HTTP (Hypertext Transfer Protocol)
• HTML (Hypertext Markup Language)
• 1991 he wrote a first web browser • 1991 www goes public • 1990: http://info.cern.ch/ • 1991: The Trojan Coffee room pot
• First webcam (real time images) 35
World wide web (www)
• 1993 NCSA Mosaic (1994 Netscape) • 1995 IE
• 1994: Pizza Hut first online webshop • 1994: Yahoo • 1995: AltaVista • 1997: AOL instant messanger • 1997: Sixdegrees.com (first modern social network) • 1997: Google.com
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And then came the explosion • 1999: Napster • 1999: Blogger • 2001: BitTorrent • 2001: Wikipedia • 2003: Skype • 2003: WordPress • 2004: Gmail • 2004: Flickr • 2005: YouTube • 2005: Facebook • 2006: Twitter • 2008: Spotify • 2009: Google Docs • 2009: (Dec): Angry Bird 37
• 1998: ADSL standard • 2001: UMTS service (3G) • 2005: VDSL2 standard • 2007: iPhone • 2007: Android • 2007: Amazone Kindle • 2009: First LTE service (4G) • 2010: iPad
Peer-to-peer paradigm
Several of the modern Internet applications are based on the Peer-to-peer (P2P) paradigm.
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Example: Skype
39 Source: http://www.technology-training.co.uk
Evolution of Internet usage (traffic volumes) seen from the users
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2007: 2011:
J. Li, A. Aurelius, V. Nordell, M. Du, Å. Arvidsson, M. Kihl: A five year perspective of traffic pattern evolution in a residential broadband access network Future Network & Mobile Summit 2012
Content distribution architectures
Media content is stored in back-end server clusters (cloud) and then distributed to clients when requested.
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Internet
Content Clients
Example:Live sport channel at TV4
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National ISPAccess network Modem
Speakers
Cache servers(http)
Production Transmission control
IP multicast network
EncodingEncryption Ingest servers Origin servers
(http)
PC / CE device (TV /
bluray)
Content Distribution
Network (CDN)Ingest servers
(http)
Performance challenges
• Client/server archictures are usually deployed: • Standardized protocols as HTTP are used.
• Control of the material.
• Client/server archtectures cause performance problems: • Heavy traffic loads on network infrastructure (unicast
transmission).
• Delays due to centralized data centers and overloaded access networks.
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One solution: P2P and caches (Spotify)
44 Source: http://www.csc.kth.se/~gkreitz/
Internet physical structure
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Internet physical structure
Sunet
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Nordunet
Internet logical structure
• Applications • MAIL, FTP, HTTP, SNMP, DNS, SSH
• Networks • TCP, UDP, IP, IPsec, Flooding, IPv4
• Point to point connection • PSK, FSK, Multiplexing, CRC, ALOHA
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Course objectives
• Introduction to computer communication and networking, with focus on the Internet.
• Digital communication
• Network access
• Internet protocols
• Routing
• Applications
• Security
• Web search
• ”Hands-on” experience in laboratory sessions. 48
