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- Linking Up: Network Basics
- Electronic Mail, Teleconferences, and Instant Messages: Interpersonal
Computing
- Converging Communication Technologies: From Messages to Money
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- 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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- The three basic components of a network:
- 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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- 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
computer’s RAM and the network cable.
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- A modem is 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
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- 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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- 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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- 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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- 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
computer’s hardware
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- 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 are hybrids, using features of the client/server and
peer-to-peer models
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- Why do people use networks?
- To share computer resources (hardware
and software)
- To support working together in new and different ways
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- 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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- 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.
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- 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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- 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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- If you don’t 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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- 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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- 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
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- 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 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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- 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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