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Chapter 9

Chapter 9 . Networking and Telecommunication. Topics. Linking Up: Network Basics Electronic Mail, Teleconferences, and Instant Messages: Interpersonal Computing Converging Communication Technologies: From Messages to Money. Linking Up: Network Basics.

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Chapter 9

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  1. Chapter 9 Networking and Telecommunication

  2. Topics • Linking Up: Network Basics • Electronic Mail, Teleconferences, and Instant Messages: Interpersonal Computing • Converging Communication Technologies: From Messages to Money

  3. Linking Up: Network Basics • A computer network is any system of two or more computers that are linked together. • How do networks impact systems? • People share computer hardware, thus reducing costs • People share data and software programs, thus increasing efficiency and production • People work together in ways that are otherwise difficult or impossible

  4. Basic Network Anatomy • The three basic components of a network: • Hardware • Software • People • Direct Connection--one of many computers linked in an office • Remote Access--computer linked to a network through a phone line, television cable system or satellite link

  5. The Network Interface • Anetwork interface card(NIC) permits direct network connection • It adds an additional serial port to the computer • The network interface card controls the flow of data between the computer’s RAM and the network cable.

  6. Communication á la Modem • Amodemis a hardware device that connects a computer’s serial port to a telephone line (for remote access). • May be internal on the system board or external modem sitting in a box linked to a serial port. • Modem transmission speed is measured in bits per second (bps) and generally transmit at 28,000 bps to 56.6K bps

  7. Conversion of Signals Computers send digital signals. The modem (modulator/demodulator) converts the digital signals to analog so that the message can be transmitted through telephone lines.

  8. Conversion of Signals The modem (modulator/demodulator) converts the analog signals back to digital signals that are understood by the computer

  9. Faster Modem Alternatives:Broadband Technologies • DSL - Digital Subscriber Line • Uses standard phone lines • Makes use of unused frequencies in phone lines • Speed dependent on distance from main office • Cable Modems • Uses cable television networks • Makes use of unused channel frequencies • Speed dependent on number of users on network at a given time

  10. Networks Near and Far Local-area network (LAN) • Computers are linked within a building or cluster of buildings. • Each computer and peripheral is an individual node on the network. • Nodes are connected by cables which may be either twisted pair (copper wires) or coaxial cable.

  11. Networks Near and Far Wide-area network (WAN) • A network that extends over a long distance. • Each network site is a node on the network. • Data transmitted over common pathways called abackbone.

  12. Wide-Area Networks • Made up of LANs linked by phone lines, microwave towers, and communication satellites. • Bridges, routers, and gateways are hardware devices that pass messages between networks.

  13. Communication Software • Protocol - set of rules for the exchange of data between a terminal and a computer or between two computers • Communication softwareestablishes a protocol that is followed by the computer’s hardware

  14. Communication Software • Many forms: • Network operating system(NOS)- handles communications between many workstations • Client/server model- one or more computers act as dedicated serves and all the remaining computers act as clients • Peer-to-peer model- every computer on the network is both client and server • Many networks arehybrids, using features of the client/server and peer-to-peer models

  15. Client/Server Model Server software responds to client requests by providing data Client software sends requests from the user to the server

  16. The Network Advantage • Why do people use networks? • To share computer resources (hardware and software) • To support working together in new and different ways Lotus Notes is a groupware application that facilitates information sharing and workgroup collaboration.

  17. E-mail Mail, Teleconferences, and IM: Interpersonal Computing • Electronic mail, teleconferencing and instant messaging allow communications between two or more people. • Meetings can be held in real-time (synchronous) or delayed (asynchronous) • Chat rooms are examples of synchronous communications; bulletin boards are examples of asynchronous communications.

  18. The Postal Alternative • E-mail is fast. • E-mail doesn’t depend on location. • E-mail facilitates group communication. • E-mail messages are digital data that can be edited and combined with other computer-generated documents.

  19. Advantages of E-mail and Teleconferencing • On-line communication is less intrusive. • On-line communication allows time shifting. • Teleconferences and e-mail promotes teleworking. • Teleconferences and e-mail emphasize the message over the messenger.

  20. On-line Issues for E-mail and Teleconferencing • Vulnerable to machine failures, network glitches, human errors and security • Threat to privacy • E-mail forgery • Information overload • Missing “human” elements of communication

  21. Converging Communication Technologies: From Messages to Money • On-line Information Services • Fax Machines and Fax Modem • Voice Mail and Computer Telephony • Global Positioning System • Video Teleconferencing • E-Money

  22. Physical Media for Networks Networks are built on physical media. • Twisted pair (Category 5) • Twisted pair (Traditional) • Coaxial Cable • Fiber optic • Wireless/infrared • Wireless/radio What affects network performance? • Bandwidth and maximum operating distance “Never in history has distance meant less.” Alvin Toffler

  23. Bandwidth • The amount of information that can be transmitted in a given amount of time • Impacted by: • Physical media that make up the network • Amount of network traffic • Software protocols of the network • Type of network connection

  24. Fiber Optic Cables • Fiber optic cables are replacing aging cooper lines with high-capacity fiber optic cables. • They use light waves to carry information at blinding speeds. • A single fiber optic cable can transmit half a gigabit (500 million bits) per second, replacing 10,000 standard telephone cables. • Data is transmitted more accurately and reliably.

  25. Digital Communication Comes Home • Digital communication lines will radically change services to our homes. • Multi-person video phone conversations, universal e-mail, customized digital newspapers, automatic utility metering and unlimited entertainment options

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