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Computer Networks

Computer Networks. Lecture 1: Introduction Prof. Younghee Lee Some part of this teaching materials are prepared referencing the lecture note made by F. Kurose and Keith W. Ross. Computer Networks: ICE1230. Overview It introduces the concepts clearly first.

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Computer Networks

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  1. Computer Networks • Lecture 1: Introduction Prof. Younghee Lee • Some part of this teaching materials are prepared referencing the lecture note made by F. Kurose and Keith W. Ross

  2. Computer Networks: ICE1230 • Overview • It introduces the concepts clearly first. • It examines network applications • client-server model, socket API, DNS, e-mail file transfer, Web browsing. • And the explanation of how the underlying communication component works, fundamental of packet switching, basic principles of various Internet protocols including Protocols such as IP, TCP, ICMP, ARP • Finally, it examines new technologies of computer networks • The course involves lecture, reading/discussion and homework. http://cnlab.icu.ac.kr/~yhlee, Room 635, 866-6112, yhlee@icu.ac.kr • Office hour: 13:30-14:30 (Mon) &13:30-14:30 (Thur) Or by appointment • Class hour: 16:00-17:30 (Mon) &16:00-17:30 (Thur) , L501 • Text • Computer Networking: A Top-down Approach Featuring the Internet Third edition by Jim Kurose and Keith Ross, Addison Wesley, 2005 • TA • Dohyun Kim, Jinchel Kim: Room 617: 866-6251

  3. Computer Networks? • Computer Networks: Interconnected Collection of Autonomous Computers • Bus, LAN, MAN, WAN • (The Internet, The TCP/IP Internet):The set of subnetwork that are interconnected through TCP/IP • interconnection of many networks:an internetwork => an internet

  4. The Internet?

  5. protocols: control sending, receiving of msgs e.g., TCP, IP, HTTP, FTP, PPP Internet: “network of networks” loosely hierarchical public Internet versus private intranet Internet standards RFC: Request for comments IETF: Internet Engineering Task Force What’s the Internet: “nuts and bolts” view router workstation server mobile local ISP regional ISP company network

  6. Computer Networks? 0.1 m Circuit board Data flow machine 1m System Multiprocessor 10m Room 100m Building Local Network 1km Campus 10km City Metropolitan Area 100km Country (Wide Area) Network 1,000km Continent 10,000km Planet The Internet

  7. Computer Networks: Bandwidth-Distance Characteristics Data Rate MPS (BPS) Local Area Network WAN MPS : Multi-Processor System 108 107 106 105 104 103 10-1 100 101 102 103 104 105 106 107 Distance, meters

  8. Applications of computer networks • Access to Remote Programs • Simulation, Computer Aided Ed.,, Medical Diagnosis • Access to Remote Data Bases • Reservations For Hotels, Airplanes, Home Banking • Automated Newspaper, Automated Library • Access to Information System: (e.g. World Wide Web) • Communication Medium • Electronic Funds Transfer System, Electronic Mail, Teleconferencing • Worldwide Newsgroups, International Contacts by Humans • Entertainment Industry • Video On Demand, Multiperson real-time simulation games • Selecting any movie/TV program ever made • Live TV may becomes interactive with audience • Pervasive computing: • Ubiquitous services : Home, office • Human centric application services • Context-aware networking

  9. Lecture Contents • Introduction, Protocols and layering • Applications: Client- server, Socket, DNS, e-mail, Web, SNMP, Security • TCP, UDP • Internetworking: Concepts, Architecture, and Protocols • Routing Principle, Internet Routing • IP, ARP, ICMP, Mobile networks • LAN, Hub, Wireless Link, PPP, WAN, Wibro, sensor network • Performance Modeling and Estimation • Multimedia Networking, Stream Protocols • Security in computer network • Network management • IPTV, VoIP, Next Generation Networks

  10. Evaluation • Evaluation • Assignment20% • Midterm exam 30% • Final exam 30% • Quiz 15% • Class participation 5%

  11. A brief Computer Networks History • Centralized: Communication within a single system • Decentralized: Communications between geographically separated component of system • Distributed: Network communications between systems • Transparent: Networking without explicit network related commands(acces, Location, Control, Execution(process migration, load balancing)) • Definition of System: a self-contained entity capable of autonomous operation

  12. 1961: Kleinrock - queueing theory shows effectiveness of packet-switching 1964: Baran - packet-switching in military nets 1967: ARPAnet conceived by Advanced Research Projects Agency 1969: first ARPAnet node operational 1972: ARPAnet demonstrated publicly NCP (Network Control Protocol) first host-host protocol first e-mail program ARPAnet has 15 nodes Internet History 1961-1972: Early packet-switching principles

  13. 1970: ALOHAnet satellite network in Hawaii 1973: Metcalfe’s PhD thesis proposes Ethernet 1974: Cerf and Kahn - architecture for interconnecting networks late70’s: proprietary architectures: DECnet, SNA, XNA late 70’s: switching fixed length packets (ATM precursor) 1979: ARPAnet has 200 nodes Cerf and Kahn’s internetworking principles: minimalism, autonomy - no internal changes required to interconnect networks best effort service model stateless routers decentralized control define today’s Internet architecture Internet History 1972-1980: Internetworking, new and proprietary nets

  14. 1983: deployment of TCP/IP 1982: smtp e-mail protocol defined 1983: DNS defined for name-to-IP-address translation 1985: ftp protocol defined 1988: TCP congestion control new national networks: Csnet, BITnet, NSFnet, Minitel 100,000 hosts connected to confederation of networks ITU Packet switch protocols: X.25… Expected to be more popular Internet History 1980-1990: new protocols, a proliferation of networks

  15. Early 1990’s: ARPAnet decomissioned 1991: NSF lifts restrictions on commercial use of NSFnet (decommissioned, 1995) early 1990s: WWW hypertext [Bush 1945, Nelson 1960’s] HTML, http: Berners-Lee 1994: Mosaic, later Netscape late 1990’s: commercialization of the WWW Late 1990’s: est. 50 million computers on Internet est. 100 million+ users backbone links runnning at 1 Gbps Internet History 1990’s: commercialization, the WWW • ITU Packet switch protocols: X.25… • Expected to be more popular • TCP/IP win!: • Web protocols are available first on the top of TCP/IP • X. protocol products were introduced to market too late and expensive.

  16. The need for Speed and Quality of service • The emergence of High Speed LANs (Amdahl's rule) • Multimedia applications • Video Conference • VoD • Live broadcasting • Mobility • Embedded Network • Network support for Pervasive computing • Service discovery, autoconfiguration

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