1 / 51

Business Data Communications, Fourth Edition

Business Data Communications, Fourth Edition. Chapter 3: Communications Media, Servers, and Clients. Learning Objectives. Describe the difference between guided media and unguided media Define twisted pair wire, coaxial cable, and fiber optic cable

coyne
Télécharger la présentation

Business Data Communications, Fourth Edition

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Business Data Communications, Fourth Edition Chapter 3: Communications Media, Servers, and Clients

  2. Learning Objectives • Describe the difference between guided media and unguided media • Define twisted pair wire, coaxial cable, and fiber optic cable • Describe how different types of cables are used in networks • List five forms of transmission that use unguided media • Describe the difference between microwave and broadcast radio Chapter 5: Communications Media, Servers, and Clients 2

  3. Learning Objectives • Identify the advantages of one medium over another in terms of cost, speed, and data reliability • Describe the use of various types of computers in a communications system • Explain the differences among servers and various types of clients • Describe the line configurations used to connect terminals in a network Chapter 5: Communications Media, Servers, and Clients 3

  4. Learning Objectives • Explain how computers and modems communicate using RS-232 connectors • List applications of the RS-449, Universal Serial Bus, and FireWire standards Chapter 5: Communications Media, Servers, and Clients 4

  5. Introduction • Devices on a network are connected using a medium • Physical wire – guided medium • Wireless – unguided medium • Cost and performance differ among the types of media Chapter 5: Communications Media, Servers, and Clients 5

  6. Guided Media • Twisted Pair Wire • Insulated copper wire, twisted to prevent interference • Unshielded twisted pair (UTP) • No extra insulation • Prone to interference • Used for residential telephones • Shielded twisted pair (STP) • Each pair of wires is in a metallic shield • Good insulation qualities • UTP Categories 1 through 6 Chapter 5: Communications Media, Servers, and Clients 6

  7. Chapter 5: Communications Media, Servers, and Clients 7

  8. Guided Media • Coaxial Cable (Coax) • Better insulation than UTP or STP • Broadband • Many channels on one physical cable • Cable TV • Baseband • One channel (or signal) on one cable • Used in computer networks Chapter 5: Communications Media, Servers, and Clients 8

  9. Chapter 5: Communications Media, Servers, and Clients 9

  10. Chapter 5: Communications Media, Servers, and Clients 10

  11. Guided Media • Fiber Optic Cable • Construction of fiber • Very pure glass or plastic • Outer sheathing to bundle the fibers • How data is transmitted • Uses a light source • Light-emitting diode (LED) • Laser Chapter 5: Communications Media, Servers, and Clients 11

  12. Chapter 5: Communications Media, Servers, and Clients 12

  13. Guided Media • Fiber Optic Cable • Multimode step index • Light bounces off the walls of the sheathing • Multimode graded index • Cable core varies in density, light bent at more shallow angles • Single-mode cable • Light travels in a straight line, due to very thin core Chapter 5: Communications Media, Servers, and Clients 13

  14. Chapter 5: Communications Media, Servers, and Clients 14

  15. Guided Media • Fiber Optic Cable • Problems with transmission of light • Attenuation – loss of signal • Dispersion – spreading of signal • Interference • Better protection than copper wires • No crosstalk occurs Chapter 5: Communications Media, Servers, and Clients 15

  16. Unguided Media • Wireless media • Broadcast radio • Omnidirectional transmission • Signals send over range of frequencies • Radio broadcast • Shortwave, citizen band • Ultrahigh frequency, very high frequency • High definition television (HDTV) • Digital Television Technology (DTV) • Digital Radio Chapter 5: Communications Media, Servers, and Clients 16

  17. Chapter 5: Communications Media, Servers, and Clients 17

  18. Unguided Media • Microwave • Unidirectional transmission • Terrestrial microwave • Satellite microwave • Geosynchronous Earth orbiting satellite (GEOS) • Satellite footprint • Transponder (uplinks, downlinks) • Propagation delay • Low Earth orbiting satellite (LEOS) • Medium Earth orbiting satellite (MEOS) Chapter 5: Communications Media, Servers, and Clients 18

  19. Chapter 5: Communications Media, Servers, and Clients 19

  20. Chapter 5: Communications Media, Servers, and Clients 20

  21. Chapter 5: Communications Media, Servers, and Clients 21

  22. Radiated Media • Microwave • Satellite microwave • Mobile satellite service (MSS) • Two-way voice and data communication • Global Mobile Personal Communications by Satellite (GMPCS) • Early warning for emergencies • Direct broadcast satellites • DirectTV • Global positioning system (GPS) • Triangulation method to determine spot on earth • Used in autos, boats, planes, golf carts Chapter 5: Communications Media, Servers, and Clients 22

  23. Chapter 5: Communications Media, Servers, and Clients 23

  24. Unguided Media • Cellular Radio • Cellular telephones • Broadcast area • Cells • Antenna in each cell • Used for voice and data • Transmissions can be picked up by scanners • Cloning occurs less frequently now Chapter 5: Communications Media, Servers, and Clients 24

  25. Chapter 5: Communications Media, Servers, and Clients 25

  26. Unguided Media • Spread Spectrum Radio • Spreads radio transmission over a range rather over a narrow frequency • Any device in the area can pick up the signal • Frequency-hopping spread spectrum • Signal hops over a series of frequencies • Devices must be synchronized • Direct sequence spread spectrum • Signal is broadcast on several frequencies simultaneously • Chip is added to identify the transmission to devices • Several users can use the same frequency • LANs use DSSS Chapter 5: Communications Media, Servers, and Clients 26

  27. Unguided Media • Infrared Transmission • Light signals sent at a frequency that cannot be seen • Used in remote controls • IrDA ports used with printers, keyboards, mouse • LANs use this for wireless transmission Chapter 5: Communications Media, Servers, and Clients 27

  28. Selection of Media • Cost • UTP is least expensive • Fiber optic cable most expensive • Speed • UTP slowest • Fiber Optic cable is fastest • Rate of Errors • Security Chapter 5: Communications Media, Servers, and Clients 28

  29. Computers and Terminals in a Communications Network • Computers in a Network • Wide Area Network (WAN) • Covers large geographic area • Local Area Network (LAN) • Limited geographic area • Computers are nodes on a network • Server – controlling computer • Client – many types of devices that use information on the server Chapter 5: Communications Media, Servers, and Clients 29

  30. Computers and Terminals in a Communications Network • Mainframe Computers and Supercomputers • Host Computers • Accessed by many terminals • Acts as a server in a network • Used in WANs and LANs • Supercomputers • Weather forecasting, space travel • Universities and the government generally own them Chapter 5: Communications Media, Servers, and Clients 30

  31. Chapter 5: Communications Media, Servers, and Clients 31

  32. Computers and Terminals in a Communications Network • Midrange computers • Smaller and slower than mainframe • May be used as a server • Used in WANs and LANs • Departmental computing • Personal Computers • May be a server or a client • Extremely versatile Chapter 5: Communications Media, Servers, and Clients 32

  33. Chapter 5: Communications Media, Servers, and Clients 33

  34. Computers and Terminals in a Communications Network • Clients (Terminals) • Device for input/output • Dumb terminals • No processing or storage capability • No buffers • Operates in uncontrolled mode • Asynchronous transmission • Smart terminals • Has memory and buffer • Operates in controlled mode • Synchronous transmission Chapter 5: Communications Media, Servers, and Clients 34

  35. Computers and Terminals in a Communications Network • Clients (Terminals) • Intelligent Terminals • Memory • Contains firmware • Operate in controlled mode • Programmable Terminals • Limited memory and processing capability • Can act as stand-alone devices • Less flexible than a PC • Popular before PCs Chapter 5: Communications Media, Servers, and Clients 35

  36. Computers and Terminals in a Communications Network • Clients (Terminals) • X Terminal • Uses X Windows • Graphical client used with TCP/IP or UNIX • Can access many servers simultaneously • Terminal Emulation • Thin-Client (Network) Computer • Used only to connect to a network • Network Personal Computer • Has some memory and storage Chapter 5: Communications Media, Servers, and Clients 36

  37. Computers and Terminals in a Network • Special-Purpose Terminals • Point-of-Sale Terminals • Uses bar code reader to read UPC • Credit Card Authorization Devices • Smart Card • Automated Teller Machines • Airline Reservation Systems Chapter 5: Communications Media, Servers, and Clients 37

  38. Chapter 5: Communications Media, Servers, and Clients 38

  39. Computers and Terminals in a Communications Network • Special-Purpose Terminals • Network Printers • Facsimile Machines • Telephone • Remote Input Clients • Utility use • Rental car agencies • Engineering Industry Clients • CAD/CAM Chapter 5: Communications Media, Servers, and Clients 39

  40. Network Configurations • Configuration is the way servers and clients are connected in a network • Point-to-Point • Direct line between sending and receiving device • Point-to-Point Protocol • Multipoint • Many clients on a shared circuit • Response time is how long a client waits for a response from the server Chapter 5: Communications Media, Servers, and Clients 40

  41. Chapter 5: Communications Media, Servers, and Clients 41

  42. Chapter 5: Communications Media, Servers, and Clients 42

  43. Terminal Interfaces • Interface • How devices are connected to a network • Data Communication Equipment (DCE) • Modems, media, switching equipment • Data Terminal Equipment (DTE) • Clients, servers, concentrators, multiplexers • EIA RS-232F • Interface that connects DCE to DTE • 25-pin electrical connection • Used on a serial port • Compare to parallel port Chapter 5: Communications Media, Servers, and Clients 43

  44. Chapter 5: Communications Media, Servers, and Clients 44

  45. Chapter 5: Communications Media, Servers, and Clients 45

  46. Terminal Interfaces • RS-449 • 37-pin connector • Allows expanded functions • Universal Serial Bus (USB) • Used for low-volume I/O devices • FireWire • High-speed video and audio connections • Handshaking Chapter 5: Communications Media, Servers, and Clients 46

  47. Chapter 5: Communications Media, Servers, and Clients 47

  48. Summary • Three types of guided media • Twisted pair • Coaxial cable • Fiber optic cable • Unguided media use no wires • Radio • Microwave • Infrared Chapter 5: Communications Media, Servers, and Clients 48

  49. Summary • Least expensive is twisted pair • Most expensive is fiber optic cable • Fiber optic transmits at fastest speed • Error rate is lowest on fiber optic cable • Fiber optic cable is the most secure medium Chapter 5: Communications Media, Servers, and Clients 49

  50. Summary • Mainframes, supercomputers, minicomputers, personal computers can be part of a network • Terminals are general-purpose or special-purpose • Point-to-point configurations • Multipoint configurations • Terminals connections - RS-232F or RS-449 • USB and FireWire are new interface standards Chapter 5: Communications Media, Servers, and Clients 50

More Related