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Topics Lesson 7

Topics Lesson 7 Basic Telecommunication Concepts Telecommunication Models Networking Client/server Computing Telecommunication Standards Wireless Communications Internet Modems Baud - transfer rate (bits per second) Analog signals: continuous Digital signals: discrete

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Topics Lesson 7

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  1. Topics Lesson 7 • Basic Telecommunication Concepts • Telecommunication Models • Networking • Client/server Computing • Telecommunication Standards • Wireless Communications • Internet

  2. Modems • Baud - transfer rate (bits per second) • Analog signals: continuous • Digital signals: discrete • Modulation: translating digital data to analog • Demodulation: translating analog data to digital • Modems modulate & demodulate data • Fax/Modem • telephone as well as facsimile

  3. Modems • A typical telephone line can only accommodate an analog signal (a continuous, curving signal) • A computer generates a digital signal representing bits • Modem: a device that translates data from digital to analog and analog to digital

  4. Figure 6.8: How a Modem Works

  5. Figure 6.3: Elements of a Telecommunications System

  6. Electronic Communication Terminology • Simplex • one way (i.e. transmit, or receive) • Half Duplex • both directions (one-at-a-time) • Full Duplex • both directions at the same time • Baud vs. bit/s (bps)

  7. Electronic Communication Modes • Communications Protocols • Handshaking • Redundancy • CRC – Cyclic Redundancy Checking

  8. Multiplexers • Multiplexers (a.k.a. “mux”): device that allows several telecommunications signals to be transmitted over a single communications medium at the same time • Demultiplexer (“demux”) • http://en.wikipedia.org/wiki/Multiplexer

  9. Front-End Processors • Front-end processors: special-purpose computers that manage communications to and from a computer system (to networks, peripheral devices) • Connect a midrange or mainframe computer to hundreds or thousands of communications lines

  10. Figure 6.9: Use of a Multiplexer to Consolidate Data Communications onto a Single Communications Link

  11. Figure 6.10: Front-End Processor

  12. Telecommunications Media

  13. Connections • Micro to micro (modem) • (Dumb) Terminal to host (mainframe/minicomputer) (direct wiring) • Micro to micro (direct) • LAN, WAN, PAN – Computer Networks • Uploading vs. downloading

  14. Fig 6.19

  15. Types of Media • Twisted Pair • Coaxial Cable • Fiber-Optic Cable • Wireless • Microwave Transmission, RF (WiFi, Bluetooth, cellular), Inferred

  16. Twisted Pair • Fig 6.4

  17. Coaxial Cable • Fig 6.5

  18. Fiber Optic Cable • Fig 6.6

  19. Microwave Transmission • Fig 6.7

  20. Satellite • Fig 6.8

  21. Cellular • Fig 6.9

  22. Infrared Transmission • Line of sight • Short distances

  23. Local Area Networks • Server Based (Novell/Microsoft Active Directory) • Peer-to-Peer (LANtastic, Windows) • Physically most common: Ethernet over unshielded twisted pair.

  24. Figure 6.15: The Basic Network Topologies

  25. Other • Gateway – for attaching different networks – converts one protocol to another. • WAN • Wireless (Wi-Fi (802.11), Bluetooth) • PAN

  26. What Is Client/Server? • Client/serveris a term used to describe a computing model for the development of computerized systems. This model is based on the distribution of functions between two types of independent and autonomous processes; servers and clients. • A client is any process that requests specific services from server processes. • A server is a process that provides requested services for clients. • The key to client/server power is where the requested processing takes place.

  27. What Is Client/Server? Basic Client/Server Computing

  28. Client/Server Systems Benefits • Client/Server Benefits • Platform-independent system development • Optimized distribution of processing activities among different platforms • Use of user friendly, cost effective, and compatible techniques, methodologies, and specialized tools

  29. Managerial Expectations ofClient/Server Systems Benefits • Organizational Expectations of Client/Server Benefits • Flexibility and adaptability • Improved employee productivity • Improved company work flow and a way to re-engineer business operations • New opportunities to provide competitive advantages • Increased customer service satisfaction

  30. Client/Server Architecture • Components of Client/Server Architecture • Client. The client is any computer process that requests services from the server. It is also known as the front-end application. • Server. The server is any computer process providing services to the clients. The server is also known as the back-end application.

  31. Client/Server Architecture • Client Components • Powerful hardware • An operating system capable of multitasking • A graphical user interface (GUI) • Communications capability

  32. Client/Server Architecture • Types of Services • File services • Print services • Fax services • Communications services • Database services • Transaction services • Application services • Web Services

  33. The Internet, Intranets, and Extranets

  34. Types of Internet Connections • Dialup (Modem) • ISDN (It Still Does Nothing, Innovations Subscribers Don't Need) • Broadband (“high speed”) • DSL (ADSL) – (Asynchronous Digital Subscriber Line) • Cable • T1, T2, T3, T4

  35. Use and Functioning of the Internet

  36. The Internet • See Introduction to the Internet and the WWW

  37. What is the Internet • a global set of interconnected data networks running the TCP/IP protocols • Traditional services include email, file transfer (FTP); current focus is on the World Wide Web • Largely self-financing; no single point of control or administration (ANARCHY)

  38. How the Internet Works • Hosts • Routers forward packets to other networks • Internet Protocol Stack (TCP/IP) • Internet Protocol (IP) • Transport Control Protocol (TCP) • Backbones

  39. How the Internet Works • Uniform Resource Locator(URL) • http://www.whitehouse.gov World Wide Web Domain category Hypertext transfer protocol Host Network Name

  40. Table 7.1

  41. Figure 7.3: Several Ways to Access the Internet

  42. Structure of the Internet • National/global backbone networks • Network Access Points (NAPS) connecting the major commercial backbones • Internet Service Providers (ISPS) • “wholesale”:selling access to Users and other ISPS • “retail”:resell access to someone else's backbone

  43. The World Wide Web

  44. The World Wide Web • World Wide Web: AKA the Web, WWW, or W3 • A menu-based system that uses the client/server model • Organizes Internet resources throughout the world into a series of menu pages, or screens, that appear on your computer • Hypermedia: tools that connect the data on Web pages, allowing users to access topics in whatever order they wish

  45. The World Wide Web (continued) • Hypertext Markup Language (HTML): the standard page description language for Web pages • HTML tags: inform browsers how to format text on a Web page, and whether images, sound, and other elements should be inserted • Extensible Markup Language (XML): markup language for Web documents containing structured information, including words, pictures, and other elements

  46. Html and XML Demo

  47. Figure 7.4: Sample Hypertext Markup Language

  48. Web Software • Web browsers • Search engines • Keyword indexes: fast & broad • Subject indexes: focused searches

  49. Table 7.7

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