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Petros KAVASSALIS

Computer Networks and Communications [Δίκτυα Υπολογιστών και Επικοινωνίες] Lecture 1: Introduction Univ. of the Aegean Financial and Management Engineering Dpt. Petros KAVASSALIS. What you will learn in this course.

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Petros KAVASSALIS

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  1. Computer Networks and Communications[Δίκτυα Υπολογιστών και Επικοινωνίες]Lecture 1: IntroductionUniv. of the Aegean Financial and Management Engineering Dpt Petros KAVASSALIS

  2. What you will learn in this course • A set of fundamental concepts for understanding Data Networks and the Internet • What is the Internet? • Internet architecture and layers • Internet applications and services • New concepts in the evolution of the Internet • The Internet goes Wireless… • Familiarization with the structure and organization of Digital Networks • Business and Social Networks • Electronic Markets and Online Feedback Mechanisms

  3. Who am I? • PhDinEconomicsandManagement (Univ. ParisDauphine & Ecolepolytechnique) • Research experience • Ecolepolytechnique, Paris • MIT CenterofTechnologyPolicyandIndustrialDevelopment, MIT CTPID (MIT Internet TelecommunicationsConvergenceConsortium) • Current positions • Univ. of the Aegean (FME): Assoc. Professor • RACTI: Director of ATLANTIS Group

  4. Communication tools • e-mail: pkavassalis [at] atlantis-group.gr • Course web site: see fme website

  5. Course Textbook[http://books.google.gr/books?id=Pd-z64SJRBAC&dq=tanenbaum+networks&printsec=frontcover&source=bn&hl=el&ei=ml-dSfH9L4S2jAeJ5L3ZBQ&sa=X&oi=book_result&resnum=4&ct=result]

  6. Supplementary Texts & References William Stallings, Computer Networking with Internet Protocols, Prentice Hall, 2004 James F. Kurose and Keith W. Ross, Computer Networking: A Top-Down Approach, Addison-Wesley, 2008

  7. Students evaluation • Class Participation (20%) + • Assignments (20%) + • Final Exam (60%)

  8. What is a network? • A hardware and software communications system formed by the interconnection of three or more devices • Devices may include: • Telephones • PCs • Routers • Other communications devices (please give examples)

  9. Why use a network? • Allow multiple devices to communicate concurrently • Allow communications to proceed at the highest achievable speed • Reduce cost associated with the interconnections! • Look at that     • k = n (n-1) / 2

  10. Network: The organization of a communication network… • Assumes the use of some interconnection equipment in the middle • That was, in the early days of communications, a Central Office (CO) • That is, today, a Router (please find a router picture from the Web: what is the functionality it provides?)

  11. Trunk Lines Connect Switches to Switches and Switches to Routers Access Lines Connect Computers to Switches Like that! Client Application Server Application Message (Frame) Access Line Switch 2 Client Computer Server Computer Switch 1 Switch 3 Trunk Line Mobile Client Outside World (The Internet) Switch 4 Router Wireless Access Point 11

  12. Switching Table PortHost 10 A1-44-D5-1F-AA-4C 13 B2-CD-13-5B-E4-65 15 C3-2D-55-3B-A9-4F 16 D4-47-55-C4-B6-F9 15 C3-2D-55-3B-A9-4F Note 1: the Ethernet C3- is out Port 15 D4-47-55-C4-B6-F9 Switch 2 Port 15 3 1 C3-2D-55-3B-A9-4F A1-44-D5-1F-AA-4C B2-CD-13-5B-E4-65 12

  13. Note 2: … and Internet Host A R1 Network X Network Y Route A-B Network Z R2 Host B

  14. Network+: Functions grouped in layers

  15. The geography of the Internet

  16. Mobile network Global ISP Home network Regional ISP Institutional network Internet in a nutshell • Protocols control sending, receiving of msgs • e.g., TCP, IP, HTTP, IM, Ethernet • Composition: “network of networks” • loosely hierarchical • public Internet versus private intranet • Standards • RFC: Request for comments • IETF: Internet Engineering Task Force

  17. Mobile network Global ISP Home network Regional ISP Institutional network Infrastructures and applications… • Communication infrastructure enables various distributed applications • E-mail, Web browsing, Skypying, file sharing, online games • Communication applications are supported by • reliable data delivery from source to destination • “best effort” (unreliable) data delivery

  18. … “separated” in two blocks • IP (spanning-layer) separates information bitways from applications • Applications may work over multiple substrates (network techs) and these substrates do not pre-specify the development of new applications • [I will come back!]

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