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Data Communications & Networking

Data Communications & Networking. Chapter 1 - Introduction. Data Communication. Data communication – exchange of data between two devices via a transmission medium. Communication System Components. Data Representation. Text – represented as a bit pattern; codes often used:

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Data Communications & Networking

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  1. Data Communications & Networking Chapter 1 - Introduction

  2. Data Communication • Data communication – exchange of data between two devices via a transmission medium University of South Alabama Computer and Information Sciences

  3. Communication System Components University of South Alabama Computer and Information Sciences

  4. Data Representation • Text – represented as a bit pattern; codes often used: • ASCII; Extended ASCII; Unicode; ISO • Numbers – represented by binary equivalent • Images – bit patterns representing pixels • Audio – recording sound or music • Video – movie , motion picture University of South Alabama Computer and Information Sciences

  5. Simplex – unidirectional; one transmits, other receives Half-duplex – each can transmit/receive; communication must alternate Full-duplex – both can transmit/receive simultaneously Direction of Data Flow University of South Alabama Computer and Information Sciences

  6. Networks • Set of devices (nodes) connected by media • A node can be a computer, printer • or any device capable device capable of sending and/or receiving data University of South Alabama Computer and Information Sciences

  7. Network Criteria • Performance • affected by # users, • type of medium, • Hardware , software • often evaluate by throughput and delay University of South Alabama Computer and Information Sciences

  8. Network Criteria • Reliability • measured by frequency of failure, • recovery time, • catastrophe vulnerability University of South Alabama Computer and Information Sciences

  9. Network Criteria • Security • protection from unauthorized access, • protecting data from damage University of South Alabama Computer and Information Sciences

  10. Types of Connections • Point-to-point – dedicated • Multipoint – shared University of South Alabama Computer and Information Sciences

  11. Physical Topology • Physical or logical arrangement • 4 basic types: • mesh • star • bus • ring • May often see hybrid University of South Alabama Computer and Information Sciences

  12. Mesh Topology • Dedicated point-to-point • links to every other device University of South Alabama Computer and Information Sciences

  13. Star Topology • Dedicated point-to-point links to central controller (hub) • Controller acts as exchange University of South Alabama Computer and Information Sciences

  14. Bus Topology • Multipoint configuration • One cable acts as a backbone to link all devices University of South Alabama Computer and Information Sciences

  15. Ring Topology • Dedicated point-to-point configuration to neighbors • Signal is passed from device to device until it reaches destination • Each device functions as a repeater University of South Alabama Computer and Information Sciences

  16. Categories of Networks • Local Area Network (LAN) – smaller geographical area • Metropolitan Area Network (MAN) – network extended over an entire city • Wide Area Network (WAN) – large geographical area University of South Alabama Computer and Information Sciences

  17. Internetworks • Connection of two or more networks • Internet vs. internet University of South Alabama Computer and Information Sciences

  18. The Internet • Collaboration of more than hundreds of thousands interconnected networks • 1969 – started as ARPAnet, a small network of connected computers • 1972 - Cerf and Khan – packet delivery and Transmission Control Protocol (TCP) • Shortly thereafter – evolution of TCP/IP • A brief history of the Internet • Internet Timeline University of South Alabama Computer and Information Sciences

  19. Protocols and Standards • Why do we need them? • Protocol – set of rules that govern data communication; defines what, how, and when • Key elements – syntax, semantics, timing • Standard – provides a model for development; allows for interoperability University of South Alabama Computer and Information Sciences

  20. Standards • Types – • De jure/Formal – legislated by an officially recognized body • De facto – by convention or widespread use • Standards Organizations – committees, forums, regulatory agencies • Internet Standards • Drafts • RFC Process University of South Alabama Computer and Information Sciences

  21. Summary • Introduction to data communication, networking, and protocol standards • Next chapter… • Network models University of South Alabama Computer and Information Sciences

  22. Credits • All figures obtained from publisher-provided instructor downloads Data Communications and Networking, 3rd edition by Behrouz A. Forouzan.  McGraw Hill Publishing, 2004 University of South Alabama Computer and Information Sciences

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