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Communications & Networks

Chapter 8. Communications & Networks. Overview. Identify Various Communication Uses List Network Advantages Differentiate Network Types Describe Communications Standards Describe Communications Devices Identify Different Transmission Media. Communications. Two or More Devices

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Communications & Networks

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  1. Chapter 8 Communications & Networks

  2. Overview • Identify Various Communication Uses • List Network Advantages • Differentiate Network Types • Describe Communications Standards • Describe Communications Devices • Identify Different Transmission Media

  3. Communications • Two or More Devices • Transfer Data or Instructions • Requirements • Sending Device • Communications Device • Connects Sending Device to Channel • Connects Channel to Receiving Device • Communications Channel • Media on Which Data Travels • Receiving Device

  4. Uses • Wireless Messaging • Text Messaging • Send / Receive Text Messages Using Phone • 14-17: 60 v. 5 • Picture Messaging • Send / Receive Graphics, Pictures, Video • Sexting: 30% of 17-year-olds Pew Internet 5/10 Pew Internet 12/09

  5. Uses • GPS (Global Positioning System) • Signals Sent by Satellites Orbiting Earth • Signal Sent Every 1/1000 of a Second • Earth-based Receivers Analyze Signals • Determine Receiver’s Geographic Location • Groupware • Assists Groups in Working Together • Share Data Over Network • e.g., Schedule Meetings

  6. Uses • Web Services • Software Applications • Communicate with Other Remote Computers • Use Internet or Internal Business Network • Mashup • Combines Services from Multiple Sources

  7. Uses • Very Hard to Give Up Pew Internet 3/08

  8. Networks • Collection of Computers & Devices • Connected via • Communications Devices • Transmission Media • Advantages • Facilitating Communications • Sharing Hardware • Sharing Software • Sharing Data And Information

  9. Network Types • LAN (Local Area Network) • Network in Limited Geographical Area • Typically Within a Building • WLAN • Wireless LAN • WAN (Wide Area Network) • Large Geographic Area • Uses Many Types of Media • Internet

  10. Network Architectures • Client/Server • Client • Requests Resource Accessed from Server • Server • One or More Computers Controlling Resource • P2P (Peer-to-Peer) • Access Any Other Computer in Network • Internet File Sharing

  11. Network Topology • Configuration of Devices in a Network • Bus • Consists of Single Central Cable • All Devices Connect to it • Inexpensive & Easy to Install

  12. Network Topology • Ring • Cable Forms Closed Ring • Data Travels In One Direction • Expensive & Difficult to Install • Star • All Devices Connect to Hub • All Data Passes Through Hub • Bottlenecks Can Occur • Easy to Install

  13. Intranet & Extranet • Intranet • Internal Corporate Network • Uses Internet • Accessible to Corporate Employees • Facilitates Working in Groups • Extranet • Allows Access to Parts of a Intranet • Customers / Suppliers

  14. Protocol • Protocol • Collection of Procedures • Establish, Maintain, & Terminate Transmissions • Type of Error Checking Used • Data Compression Method, If Any • Indicate Finished Sending Message • Indicate Message Has Been Received

  15. Standards • Ethernet • For LANs • Uses Bus or Star Topology • Widely Implemented • TCP/IP • Used for Internet Transmissions • Packet Switching • Transmits Data by Breaking it Into Packets • Reassembles Data at Destination

  16. Standards • 802.11 (Wi-Fi) • Family of Standards for Wireless LANs • 802.16 (WiMAX) • Towers Cover 30-mile Radius • Provides Wireless Broadband Internet • Bluetooth • Short-range Radio Technology • WAP • Wireless Mobile Devices Connect to Internet

  17. Standards • IrDA • Data Transferred via Infrared Light Waves • RFID • Radio Signals Communicate with Tags • Failed Legislation • Nevada • Require Retailers to Inform Customers • Rhode Island • Government Agency Cannot Track Individuals • Texas • Prohibit Schools from Using RFID on Students

  18. Types & Speeds • Measured in bps (Bits per Second)

  19. Devices • Modem • Converts Analog to Digital & Vice Versa • Required for Telephone Line Communication • DSL Modem • Cable Modem • Uses Cable TV Network

  20. Devices • Wireless Modem • Internet Access • Network Card • Connects PC to Network • Wireless Access Point

  21. Devices • Router • Connects Multiple Computers / Routers • Transmits Data to Network Destination • Uses Fastest Available Path • Many Protected by Hardware Firewall • Hub / Switch • Provides Central Point for Network Cables

  22. Channel • Communication Path Between Devices • Bandwidth • Difference Between Frequencies • Amount of Data that Travel Over Channel • Latency • Time for Signal to Travel • From One Network Location to Another

  23. Channel • Broadband • Transmit Multiple Signals over Channel • Transmission Media • Materials or Techniques • Capable of Carrying Signals

  24. Physical Transmission Media • Twisted-pair • Telephone System • Coaxial Cable • Cable Television • Fiber-optic • Thin Strands of Glass or Plastic • Uses Light to Transmit Signals • Less Susceptible to Interference • More Secure

  25. Wireless Transmission Media • Broadcast Radio • Distributes Radio Signals • Long & Short Distances • Cellular Radio • Widely Used for Mobile Communications

  26. Wireless Transmission Media • Microwave Station • Earth-based Reflective Dish • Contains Antenna, Transceivers • Uses Line-of-sight Transmission • Satellite • Space Station • Receives Microwave Signals • Amplifies Signals • Broadcasts Signals Back

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