Computer networks


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Computer networks

  1. 1. Computer Networks 教材 台北科技大學電子系 李仁貴
  2. 2. 授課用書Andrew S. Tanenbaum, “Computer Networks”, Fourth Edition, 2003, 新月圖書。 參考書目 [1] Computer Networking: A Top Down Approach Featuring the Internet, 2nd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2002. [2] Computer Networks and Internets with Internet Applications, 3th edition. Douglas E. Comer. Prentice Hall, 2001. [3] Data Communications and Networks, Achyut S. Godbole, McGraw Hill, 2003. (全華) 相關網站1. -- Some PDF files to discuss broadband & IT technologies.2. -- CATV broadband technologies.3. -- ATM Forum.4. RFC protocol for Internet.--
  3. 3. OUTLINEChapter 1: Introduction Use of Networks, Network Hardware, Network Software Reference Models, Example Networks, StandardizationChapter 2: The Physical Layer Transmission Media:Twisted Pair, Coaxial Cable, Fiber Optics, WirelessChapter 3: The Data Link Layer Error Control, Flow Control, ProtocolChapter 4: The Medium Access Control Sublayer Multiple Access, Ethernet, WLAN, Broadband Wireless, BluetoothChapter 5: The Network Layer Routing, Congestion Control, QoS, InterNetworkingChapter 6: The Transport Layer TCP , UDPChapter 7: Application Layer DNS, Mail, WWW, MultimediaChapter 8: Network Security
  4. 4. Chapter 1Introduction
  5. 5. Uses of Computer Networks• Business Applications Resource Sharing (File system, client-Server, Internet)• Home Applications• Mobile Users• Social Issues
  6. 6. Business Applications of Networks A network with two clients and one server.
  7. 7. Business Applications of Networks (2) The client-server model involves requests and replies.
  8. 8. Home Network Applications• Access to remote information• Person-to-person communication• Interactive entertainment• Electronic commerce B2C: Business-to-consumer B2B: Business-to-business G2C: Government-to-consumer C2C: Consumer-to-consumer P2P: Peer-to-peer
  9. 9. Home Network Applications (2)In peer-to-peer system there are no fixed clients and servers.
  10. 10. Home Network Applications (3) Some forms of e-commerce.
  11. 11. Mobile Network UsersCombinations of wireless networks and mobile computing.
  12. 12. Network Hardware• Local Area Networks• Metropolitan Area Networks• Wide Area Networks• Wireless Networks• Home Networks• Inter-networks
  13. 13. Operation ModeUni-casting : one sender and one receiverBroad-casting: A sender to transmit and all machine on the network to receive.Multi-casting : Broad-cast systems support transmission to a subnet of the network.
  14. 14. Broadcast NetworksClassification of interconnected processors by scale.
  15. 15. Local Area NetworksTwo broadcast networks(a) Bus(b) Ring
  16. 16. Metropolitan Area Networks A metropolitan area network based on cable TV.
  17. 17. Wide Area NetworksPoint- to-pointStore and forwardPacket switched Relation between hosts on LANs and the subnet.
  18. 18. Wide Area Networks (2)A stream of packets from sender to receiver.
  19. 19. Wireless NetworksCategories of wireless networks:• System interconnection• Wireless LANs• Wireless WANs
  20. 20. Wireless Networks (2) (a) Bluetooth configuration (b) Wireless LAN
  21. 21. Wireless Networks (3)(a) Individual mobile computers(b) A flying LAN
  22. 22. Home Network Categories• Computers (desktop PC, PDA, shared peripherals)• Entertainment (TV, DVD, VCR, camera, stereo, MP3)• Telecomm (telephone, cell phone, intercom, fax)• Appliances (microwave, fridge, clock, furnace, airco)• Telemetry (utility meter, burglar alarm, babycam).
  23. 23. Network Software• Protocol Hierarchies (protocol Stack)• Design Issues for the Layers• Connection-Oriented and Connectionless Services• Service Primitives• The Relationship of Services to Protocols
  24. 24. Network SoftwareProtocol Hierarchies (Protocol Stack) Layers, protocols, and interfaces.
  25. 25. Protocol Hierarchies (2) Location A Location B I like Jaime Message Philosopher rabbits bien les lapins 3 3 Information L: Dutch for the remote Translator L: Dutch Ik vind translator Ik vind konijnen konijnen 2 2 leuk leuk Information Fax #--- for the remote Fax #--- L: Dutch secretary Secretary L: Dutch Ik vind Ik vind 1 1 konijnen konijnen leuk leukThe philosopher-translator-secretary architecture.
  26. 26. Protocol Hierarchies (3)Example information flow supporting virtual communication in layer 5.
  27. 27. Design Issues for the Layers• Addressing• Error Control• Flow Control• Multiplexing• Routing
  28. 28. Connection-Oriented and Connectionless Services Six different types of service.
  29. 29. Service PrimitivesFive service primitives for implementing a simple connection- oriented service.
  30. 30. Service Primitives (2)Packets sent in a simple client-server interaction on a connection-oriented network.
  31. 31. Services to Protocols Relationship The relationship between a service and a protocol.
  32. 32. Reference Models• The OSI Reference Model• The TCP/IP Reference Model• A Comparison of OSI and TCP/IP• A Critique of the OSI Model and Protocols• A Critique of the TCP/IP Reference Model TCP : Transmission Control Protocol UDP : User Datagram Protocol
  33. 33. Reference ModelsThe OSIreference model.
  34. 34. Reference Models (2) The TCP/IP reference model.
  35. 35. Reference Models (3)Protocols and networks in the TCP/IP model initially.
  36. 36. Comparing OSI and TCP/IP Models Concepts central to the OSI model • Services • Interfaces • Protocols
  37. 37. A Critique of the OSI Model and Protocols Why OSI did not take over the world • Bad timing • Bad technology • Bad implementations • Bad politics
  38. 38. Bad TimingThe apocalypse of the two elephants.
  39. 39. A Critique of the TCP/IP Reference Model Problems: • Service, interface, and protocol not distinguished • Not a general model • Host-to-network “layer” not really a layer • No mention of physical and data link layers • Minor protocols deeply entrenched, hard to replace
  40. 40. Hybrid ModelThe hybrid reference model to be used in this book.
  41. 41. Example Networks• The Internet• Connection-Oriented Networks: X.25, Frame Relay, and ATM• Ethernet• Wireless LANs: 802:11
  42. 42. The ARPANET(a) Structure of the telephone system.(b) Baran’s proposed distributed switching system.
  43. 43. The ARPANET (2)IMP: Interface Message Processor The original ARPANET design.
  44. 44. The ARPANET (3)Growth of the ARPANET (a) December 1969. (b) July 1970.(c) March 1971. (d) April 1972. (e) September 1972.
  45. 45. NSFNETThe NSFNET backbone in 1988.
  46. 46. Internet UsageTraditional applications (1970 – 1990)• E-mail• News• Remote login• File transfer
  47. 47. Architecture of the Internet Overview of the Internet.
  48. 48. ATM Virtual Circuits A virtual circuit.
  49. 49. ATM Virtual Circuits (2) An ATM cell.
  50. 50. The ATM Reference Model The ATM reference model.
  51. 51. The ATM Reference Model (2) The ATM layers and sublayers and their functions.
  52. 52. EthernetArchitecture of the original Ethernet.
  53. 53. Wireless LANs(a) Wireless networking with a base station.(b) Ad hoc networking.
  54. 54. Wireless LANs (2)The range of a single radio may not cover the entire system.
  55. 55. Wireless LANs (3) A multicell 802.11 network.
  56. 56. Network Standardization• Who’s Who in the Telecommunications World• Who’s Who in the International Standards World• Who’s Who in the Internet Standards World
  57. 57. ITU• Main sectors • Radiocommunications • Telecommunications Standardization • Development• Classes of Members • National governments • Sector members • Associate members • Regulatory agencies
  58. 58. IEEE 802 StandardsThe 802 working groups. The important ones are marked with *. The ones marked with are hibernating. The one marked with † gave up.