Chapter 5 - Communication & Network

8/13/2019 Chapter 5 - Communication & Network

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CHAPTER 5

COMMUNICATION AND NETWORK


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CommunicationsWhat are computer communications?

Process in which two or more computers or devices transfer data,

instructions, and information


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Sending

deviceinitiates

instruction to

transmit data,instructions, or

information

CommunicationsWhat is needed for successful communications?

Communications

device

connectsthe communications

channel to the

receiving device

Receiving

device

acceptstransmission of data,

instructions, or

information

Communications

deviceconnects

the sending device to

the communicationschannel

Communications

channelmedia

on which data,

instructions, orinformation travel


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Uses of Computer CommunicationsWhat are some uses of communications technology?


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Uses of Computer Communications

What are wireless messaging services?

Wireless instant

messagingallows

wireless mobiledevices to exchange

messages

Text messaging

allows users to send

and receive shorttext messages on a

phone or other

mobile device

Picture/video

messaging allows

users to sendgraphics, pictures,

video clips, sound

files, and short text

messages


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Uses of Computer CommunicationsWhat are wirelessInternet access pointsand cybercafs?

Next

Wireless Internet accesspointallows wireless

connection to Internetin public location

3G and 4Gnetworks

Cybercafis a coffeehouse that providescomputers with Internetaccess


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Uses of Computer CommunicationsWhat is a global positioning system (GPS)?Step 1.GPS satellites orbit

Earth. Every

thousandth of a

second, each satellite

sends a signal thatindicates its current

position to the GPS

receiver.

Step 2.A GPS receiver

(such as in a car,

a wearable

device, a smartphone, a

handheld device,

or a collar)

determines its

location on Earth

by analyzing at

least 3 separatesatellite signals

from the 24

satellites in orbit.


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Uses of Computer CommunicationsWhat are collaborationand

groupware?

Web conference

Groupwareis software

that allows people

work together and share

information

Collaborationis working

with other users connected

to a server


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Uses of Computer CommunicationsWhat are voice mailand web services? Voice mailis voice message

converted to digital form

Web services describe

standardized software thatenables programmers to

create applications that

communicate with other

remote computers over the

Internet or on an internal

business network


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NetworksWhat is a network? Collection of

computers anddevices connectedvia communications

devices andtransmissionmedia


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Types of NetworkWhat is a local area network (LAN)Local Area Network (LAN)network connecting

information processing devices within a limited physical

area. LANs allow end users in a workgroup to communicate

electronically; share hardware, software, and data resources;and pool their efforts when working on group projects


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Types of NetworksWhat is a wide area

network (WAN)?Wide Area Network (WAN)

network that covers a large

geographic area/ to cover

great distances, WANs may

transmit data over leased

high-speed phone lines or

wireless links such as

satellites.


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Types of NetworksWhat is a peer-to-

peer network? Simple network

that connects

fewer than 10computers

Each computer,

or peer, has equal

capabilities


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Types of NetworkWhat is Virtual Private

Network?

Virtual Private Network (VPN)

secure network that uses the

Internet as its main backbone

network, but relies on network

firewalls, encryption, and other

security features of its Internet

and intranet connections and

those of participatingorganizations


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Types of Network

Network ComputingThin clients provide a

browser-based user interface for processing

small application programs.


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Networks TopologyWhat is a bus network? All computers and devices connect to central

cable or bus

Example of network topology(layout of devices in

network)

Popular topologies are bus, ring, and star


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NetworksWhat is a ring network? Cable forms closed

loop (ring), with all

computers and devices

arranged along ring Data travels from

device to device

around entire ring, in

one direction


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Network Communications StandardsWhat areUWB, IrDA,RFID, WiMAX,and Wireless

Applications Protocol (WAP)?IrDAspecification allows

data to be transferred

wirelessly via infrared

light waves

Wireless Applications

Protocol (WAP)allow wireless mobile devices

to access Internet

Radio Frequency

Identification (RFID)uses radio signals to communicate

with a tag placed in an object

Worldwide Interoperability

for Microwave Access (WiMAXor 802.16)

standard that specifies how wireless

devices communicate over the air

in a wide area

UWBspecification allows

data to be transferred

wirelessly via short-range

radio waves


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Communications Over the Telephone NetworkWhat is the public switched

telephone network (PSTN)? Worldwide telephone

system that handles

voice-oriented

telephone calls


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Communications Over the Telephone Network

What is a dial-up line? Temporary connection using telephone line for

communications

Costs no more than making regular call

Computers at any two locations can establish aconnection using modems and telephone network


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Communications 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


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Communications DevicesWhat is a dial-upmodem? A dial-up modem converts digital signals to analog signals

and vice versa

Usually in the form of an adapter card


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Communications DevicesWhat are ISDN and DSL 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


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Communications DevicesWhat is a wireless modem? Allows access to the

Web wirelessly from

a notebook

computer, a smart

phone, or other

mobile device

Typically use the

same waves used by

cellular telephones


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Communications DevicesWhat is a network card? Adapter card, PC

Card, ExpressCard

module, USB

network adapter, or

flash card that

enables computer or

device to access

network

Sometimes called

network interface

card (NIC)


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Communications 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


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Communications 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


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Communications DevicesWhat is a hub or switch? Device that provides central

point for cables in network


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Home 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 Phonelineuse

telephone lines


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Communications ChannelWhat is a communications channel? Transmission media on which data travels in

communications system

Bandwidthis amount of

data that can travel

over a communicationschannel

Transmission media

are materials orsubstances capable of

carrying one or more

signals


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Physical Transmission MediaWhat is physical transmission media? Wire, cable,

and other tangiblematerials usedto send

communicationssignals


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Physical Transmission MediaWhat are twisted-pair cableand coaxial cable? Twisted-pair cableis used for telephone systems and network cabling

Coaxial cableis often used for cable television wiring


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Physical Transmission MediaWhat is fiber-optic cable?

Nextp. 493 Fig. 9-39

Capable of carrying

significantly more

data at faster speeds

than wire cables

Less susceptible

to interference

(noise) and, therefore,

more secure

Smaller size (thinnerand lighter)


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Wireless Transmission MediaWhat is wireless transmission media? Used when inconvenient, impractical, or impossible to

install cables

Includes Bluetooth and IrDA


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Wireless Transmission MediaWhat are broadcast radioand cellular radio? Broadcast radio

distributes radio

signals over long

and short distances

Cellular radio

is form of

broadcast radio

used for mobile

communications


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Wireless Transmission MediaWhat is a microwavestation? Earth-based

reflective

dish used for

microwave

communications Must transmit in

straight line with

no obstructions


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Wireless Transmission MediaWhat is a communications satellite? Space station

that receives

microwave signals

from earth-based

station, amplifiessignals, and

broadcasts signals

back to any

number of earth-

based stations

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