Networking

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Chapter 9
Networking and Telecommunication
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Topics

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

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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

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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

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The Network Interface

• A network 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 computers RAM and the network
  cable.

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Communication á la Modem

• A modem is a hardware device that connects a
  computers 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

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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.

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

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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 a
  backbone.

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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.

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Communication Software

• Communication software software that enables
  computers to interact with each other over a
  telephone line or other network
• Protocol - set of rules for the exchange of data
  between a terminal and a computer or between two
  computers
• Communication software establishes a protocol
  that is followed by the computers hardware

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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 (P2P) - every computer on the
  network is both client and server

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

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The Postal Alternative

• E-mail is fast.
• E-mail doesnt 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.

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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.

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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

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Rules of Thumb On-line Survival Tips

• If you dont have to be on line, go off line.
• Avoid peak hours
• Let your system do as much of the work as
  possible.
• Store names and addresses in an on-line address
  book

• Protect your privacy
• Cross-check on-line information sources
• Be aware and awake
• Avoid information overload.

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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

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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
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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

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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.

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Wireless Communication

• Wi-Fi or 802.11b allows multiple computers to
  connect to a LAN through a base station up to
  150ft away
• Bluetooth overcomes differences between mobile
  phones, handheld computers, and PCs, making it
  possible for all of these devices to communicate
  with each other regardless of OS
• Security is the penalty for convenience

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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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