CSC1100 - Chapter07 - Communications & Networks


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CSC1100 - Chapter07 - Communications & Networks

  1. 1. Discovering Computers 2008 Chapter 7 Communications and Networks 1
  2. 2. 2Chapter 7 Objectives Discuss the components required for successful communications Explain the purpose of communications software Identify various sending and receiving devices Describe various types of lines for communications over the telephone networkDescribe uses of computer communications Describe commonly used communications devices List advantages of using a network Discuss different ways to set up a home network Differentiate among client/server, peer-to-peer, and P2P networks Identify various physical and wireless transmission media Describe the various network communications standards
  3. 3. 3CommunicationsWhat are computer communications? Process in which two or more computers/devices transfer data, instructions, and information
  4. 4. 4CommunicationsWhat is needed for successful communications? Sending Communications Communications device — initiates device — connects channel — media instruction to the sending device to on which data, transmit data, the communications instructions, or instructions, or channel information travel information Communications Receiving device — connects device — accepts the communications transmission of data, channel to the instructions, or receiving device information
  5. 5. 5Uses of Computer CommunicationsWhat are some uses of communications technology? Instant Internet Web E-Mail Messaging Internet Chat Rooms Newsgroups Telephony Fax Machine Web Video FTP or Computer Folders Conferencing Fax/Modem
  6. 6. 6What are wireless messaging services?TEXT MESSAGING Limit messages to usually fewer than 300 characters Text messaging Mobile to Mobileallows users to send Mobile to E-Mail and receive short Web to Mobile text messages Mobile to Provider: use common (SMS) on a phone short code – 4 or 5 digit num or PDA assigned to specific content or wireless service provider, followed by message – e.g. vote for TV prg contestant
  7. 7. 7What are wireless messaging services?PICTURE MESSAGING Video messaging: to send short video clips (about 15 seconds) Smart phones & PDAs with picture/video messaging also called MMS (multimedia message service) Camera phone, video phone Mobile to Mobile Mobile to E-Mail Picture messaging allows users to send graphics, pictures, video clips, sound Video files, and short text messaging messages
  8. 8. 8What are wireless messaging services?WIRELESS INSTANT MESSAGING (IM) Real-time Internet communications service that allow wireless mobile devices to exchange messages with one or more mobile devices or online users Some WISP provide IM service: smart phone & PDAs can be used to send & receive instant messages AOL Instant Messenger (AIM), Yahoo! Messenger Mobile to Mobile Wireless instant Mobile to PC messaging allows Web to Mobile wireless mobile devices to exchange messages
  9. 9. 9Uses of Computer CommunicationsWhat are wireless Internet access pointsand cybercafés? Wireless Internet access point allows wireless connection to Internet in public location Hot sport, 3G network Cybercafé is coffee house that provides computers with Internet access – some are also hot spots
  10. 10. 10Uses of Computer CommunicationsWhat is a global positioning system (GPS)? Navigation system consists of one or more earth-based receivers that accept & analyze signals sent by satellites in order to determine the geographical location GPS receiver: handheld, mountable or embedded device containing an antenna, a radio receiver and a processor – many include screen display showing an individual’s location on a map
  11. 11. 11 Uses of Computer Communications What is a global positioning system (GPS)? Step 2.Step 1. A GPS receiverGPS satellites orbit (such as in a car, aEarth. Every wearable device, athousandth of a smart phone, asecond, each satellite handheld device,sends a signal that or a collar)indicates its current determines itsposition to the GPS location on Earthreceiver. by analyzing at least 3 separate satellite signals from the 24 satellites in orbit.
  12. 12. 12Uses of Computer CommunicationsWhat are collaboration and groupware? Collaboration or work online is working with other users connected to a server A document management system provides for storage and management of a company’s documents Groupware is software that allows people work together and share information over a network
  13. 13. 13 Uses of Computer CommunicationsWhat are voice mail and web services? Voice mail is voice message converted to digital form Web services describe standardized software that enables programmers to create applications that communicate with other remote computers over the Internet or on an internal business network doesn’t specific require prg lang, OS, or Web browser By sending properly formatted XML (eXtensive Markup Language) files to Web services
  14. 14. 14NETWORK
  15. 15. 15NetworksWhat is a network network? Collection of computers and devices connected via communications devices and transmission media What are the advantages of using a network?
  16. 16. 16NetworksWhat is a local area network (LAN and a LAN)metropolitan area network (MAN MAN)? Network in limited geographical area such as home or office building Wireless LAN (WLAN WLAN) Metropolitan area network (MAN) connects LANs in city or town
  17. 17. 17NetworksWhat is a wide areanetwork (WAN)? Network that covers large geographic area using many types of media Internet is world’s largest WAN
  18. 18. 18NETWORK ARCHITECTURES peer-to-peer & P2P
  19. 19. 19NetworksWhat is a client/servernetwork? One or more computers act as server and other computers, or clients, access server
  20. 20. 20NetworksWhat is a peer-to-peernetwork? Simple network that connects fewer than 10 computers Each computer, or peer, has equal capabilities
  21. 21. 21NETWORK TOPOLOGIES bus, ring & star (layout of devices in network)
  22. 22. 22NetworksWhat is a bus network? All computers and devices connect to central cable or bus
  23. 23. 23NetworksWhat is a ring network? Cable forms closed ring, or loop, with all computers and devices arranged along ring Data travels from device to device around entire ring, in one direction
  24. 24. 24NetworksWhat is a star network? All devices connect to a central device (hub or switch) All data transferred from one computer to another passes through hub or switch
  25. 25. 25NetworksWhat is an intranet? Internal network that uses Internet technologies Makes information accessible to employees Typically includes connection to Internet Extranet allows customers or suppliers to access part of company’s intranet
  26. 26. 26Intranet
  27. 27. 27 NETWORK COMMUNICATIONS STANDARDSEthernet, Token Ring, TCP/IP, 802.11 (Wi-Fi), Bluetooth, UWB, IrDA, RFID, WiMAX, WAP
  28. 28. 28Network Communications StandardsWhat are Ethernet and token ring? Ethernet technology allows computers to contend for access to network If two computers send data at same time, a collision occurs and computers must send the data again Token ring technology controls access to network by requiring devices to pass a special signal, called token
  29. 29. 29Network Communications StandardsWhat are TCP/IP and 802.11 (Wi-Fi)? TCP/IP (Transmission Control Protocol/Internet Protocol) technology transmits data by breaking it up into small pieces, or packets Commonly used for Internet transmissions 802.11 (Wi-Fi) is family of standards for wireless LANs
  30. 30. 30
  31. 31. 31Network Communications StandardsWhat is Bluetooth? Short-range radio waves transmit data between Bluetooth devices
  32. 32. 32 Network Communications Standards What are UWB, IrDA, RFID, WiMAX, and Wireless Applications Protocol (WAP)?UWB IrDAspecification allows specification allowsdata to be transferred data to be transferred Worldwide Interoperabilitywirelessly via short-range wirelessly via infrared for Microwave Access (WiMAXradio waves light waves or 802.16) standard that specifies how wireless devices communicate over the air Radio Frequency in a wide area Identification (RFID) Wireless Applications uses radio signals to communicate Protocol (WAP) with a tag placed in an object allow wireless mobile devices to access Internet
  33. 33. 33
  34. 34. 34 Communications Software What is communications software? System software Programs that help users establish connection to Internet, other network, or another computer Programs that help users Application manage transmission of software data, instructions, and information Programs that provide an interface for users to communicate with one anotherApplication software for communication:e-mail, FTP, Web browser, newsgroup/messageboards, chat rooms, instant messaging, videoconferencing, Internet telephony,…
  35. 35. 35Communications Over the Telephone Network Dial-Up Lines, Dedicated Lines
  36. 36. 36Communications Over the Telephone NetworkWhat is the public switchedtelephone network (PSTN)? Worldwide telephone system that handles voice-oriented telephone calls
  37. 37. 37Communications Over the Telephone NetworkWhat is a dial-up line? Temporary connection using telephone line for communications Computers at any two locations can establish a connection using modems and telephone network Costs no more than making regular call
  38. 38. 38Communications Over the Telephone NetworkWhat is a dedicated line? Always-on connection between two communications devices
  39. 39. 39Communications Over the Telephone NetworkDedicated lines: 5 types: 1.ISDN (Integrated Service Digital Network) line 2.DSL (Digital Subscriber Line), ADSL (Asymmetric …) 3.FTTH & FHHB (Fiber to the Home/Building) 4.T-Carrier line (T1, fractional T1, T3) 5.ATM (Asynchronous Transfer Mode) ISDN line technique multiplexing of carrying 3 or more signals at once through the same line
  40. 40. 40Communications Devices
  41. 41. 41Communications DevicesWhat are examples of communications devices? Common types are dial-up modems, ISDN and DSL modems, cable modems, wireless modems, network cards, wireless access points, routers, and hubs ISDN and DSL modems send and receive data from ISDN and DSL lines
  42. 42. 42Communications DevicesWhat is a dial-up modem? A dial-up modem converts digital signals to analog signals and vice versa Usually in the form of an adapter card
  43. 43. 43Communications DevicesWhat are ISDN (Integrated Service Digital Network)and DSL (Digital Subscriber Line) modems? Communications devices that send and receive digital ISDN and DSL signals Usually external devices in which one end connects to a telephone line and the other end connects to a port on the system unit
  44. 44. 44Communications DevicesWhat is a cable modem? Sends and receives data over cable television (CATV) network Much faster than dial- up modem or ISDN; speed similar to DSL Sometimes called a broadband modem Placed after cable splitter System unit has network card – e.g. Ethernet card
  45. 45. 45Communications DevicesWhat is a wireless modem? Allows access to the Web wirelessly from a notebook computer, a PDA, a smart phone, or other mobile device Typically use the same waves used by cellular telephones Has external or built-in antenna Available as PC Cards, ExpressCard modules and flash cards
  46. 46. 46 Communications DevicesWhat is a network card? Is an adapter card, PC Card, ExpressCard module, USB network adapter, or flash card that enables computer or device to access network Coordinates the transmission and receipt of data, instructions & information to & from the computer or devices containing the network card Wireless network card Sometimes called network interface card (NIC)
  47. 47. 47Communications DevicesWhat is a wireless access point? Central communications device that allows computers and devices to transfer data wirelessly among themselves or wirelessly to a wired network
  48. 48. 48Communications DevicesWhat is a router? Connects computers and transmits data to correct destination on network Routers forward data on Internet using fastest available path Some routers have a built-in hardware firewall
  49. 49. 49Communications DevicesWhat is a hub or switch? Device that provides central point for cables in network Some hubs include routers – hub receives data from many directions and then forwards it to one or more destinationsWhat are the differences between a hub & a switch & a router?
  50. 50. 50Home NetworksWhat is a home network? Multiple computers connected in home Several types of home networks Ethernet — connect computers via cable Powerline cable — use electrical lines in house Phoneline — use telephone linesWireless Home Network HomeRF network, Wi-Fi home network
  51. 51. 51Communications Channel
  52. 52. 52Communications ChannelWhat is a communications channel? Transmission media on which data travels in communications system Bandwidth is amount of Transmission media data that can travel are materials capable of over a communications carrying one or more channel signals Latency is the time it takes a signal to travel from one location to another on a network
  53. 53. 53Transmission Media Transmission media category Baseband media Broadband media transmit only one transmit multiple signals signal at a time at much faster speed Download transfer rates are faster than upload DSL, cable television Internet service, satellites,…
  54. 54. 54Communications ChannelHow is a request sent over theInternet using a communicationschannel?
  55. 55. 55Transmission Media Transmission media typesPhysical transmission media Wireless transmission media Twisted-Pair Cable, Coaxial Infrared, Broadcast Radio, Cable, Fiber Optic Cable Cellular Radio, Microwave
  56. 56. 56Physical Transmission MediaWhat is physical transmission media? Wire, cable and other tangible materials used to send communications signals
  57. 57. 57Physical Transmission MediaWhat are twisted-pair cable and coaxial cable? Twisted-pair cable is used for telephone systems and network cabling (LAN) Reduced noise – electrical disturbance that can degrade communication
  58. 58. 58Physical Transmission MediaWhat are twisted-pair cable and coaxial cable? Coaxial cable is often used for cable television wiring – long distance Single copper wire surrounded by at least 3 layers: an insulation material, a woven or braided metal, a plastic outer coating
  59. 59. 59 Physical Transmission MediaWhat is fiber-optic cable? Capable of carrying significantly more data at faster speeds than wire cables Less susceptible to interference (noise) and, therefore, more secure Smaller size (thinner and lighter)
  60. 60. 60Wireless Transmission MediaWhat is wireless transmission media? Used when inconvenient, impractical, or impossible to install cables Includes Bluetooth and IrDA
  61. 61. 61Wireless Transmission MediaWhat are broadcast radio and cellular radio? Broadcast radio distributes radio signals over long distances (btw cities, countries,…) and short distances (within an office or home) - Flexible & portable but slower, more susceptible to noise - used by Bluetooth, UMB, HomeRF, Wi-Fi, and WiMAX * Bluetooth & UMB are alternatives to infrared communications * Hot spots use Wi-Fi & WiMAX networks Cellular radio is form of broadcast radio used for mobile communications – wireless modems & cellular telephones (use high- frequency radio waves to transmit voice & digital data messages) - 1G, 2G & 3G
  62. 62. 62Wireless Transmission MediaWhat is a microwave station? Earth-based reflective dish contains antenna, transceivers and other equipments for microwave communications Microwave: radio waves at high-speed signal transmission (fixed wireless) Must be transmitted in straight line with no obstructions
  63. 63. 63Wireless Transmission MediaWhat is a communications satellite? Space station that receives microwave signals from earth-based station, amplifies (strengthens) signals, and broadcasts signals back to any number of earth-based stations (microwave stations, smart phones & GPS) - uplink down link Air navigation, television and radio broadcast, & Internet connections use communications satellites Satellite Internet connection needs a satellite dish & a satellite modem card
  64. 64. 64Summary of Communications and Networks Communications terminology and applications Various communications devices, media, and procedures How to join computers into a networkChapter 7 Complete