CSC1100 - Chapter07 - Communications & Networks

Discovering Computers 2008

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Chapter 7 Chapter 7 Chapter 7 Chapter 7

Communications Communications Communications Communications

and Networksand Networksand Networksand Networks

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Chapter 7 ObjectivesChapter 7 ObjectivesChapter 7 ObjectivesChapter 7 Objectives

Discuss the components required for successful communications

Discuss the components required for successful communications

Identify various sendingand receiving devices

Identify various sendingand receiving devices

Describe uses of computer communicationsDescribe uses of computer communications

Explain the purpose ofcommunications software

Explain the purpose ofcommunications software

Describe various types of lines for communications over the telephone network

Describe various types of lines for communications over the telephone network

Describe commonly usedDescribe commonly used

List advantages of using a networkList advantages of using a network

Differentiate among client/server,peer-to-peer, and P2P networks

Differentiate among client/server,peer-to-peer, and P2P networks

Describe the various network communications standards

Describe the various network communications standards

Describe commonly usedcommunications devicesDescribe commonly usedcommunications devices

Discuss different ways to set upa home network

Discuss different ways to set upa home network

Identify various physical and wireless transmission media

Identify various physical and wireless transmission media

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CommunicationsCommunicationsCommunicationsCommunications

What are computercommunications?� Process in which two or more computers/devices transfer

data, instructions, and information

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Sending device— initiates

instruction to transmit data, instructions, or

What is needed for successful communications?

CommunicationsCommunicationsCommunicationsCommunications

Communications device— connects

the sending device to the communications

channel

Communications channel— media

on which data, instructions, or

information travelinstructions, or information

Communications device— connects the communications

channel to the receiving device

Receiving device— accepts

transmission of data, instructions, or

information

channel information travel

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Uses of Computer CommunicationsUses of Computer CommunicationsUses of Computer CommunicationsUses of Computer Communications

What are some uses of communications technology?

WebWebWebWebInternetInternetInternetInternet EE--MailMailEE--MailMailInstantInstant

MessagingMessagingInstantInstant

MessagingMessaging

Internet Internet Internet Internet Internet Internet TelephonyTelephonyInternet Internet

TelephonyTelephonyNewsgroupsNewsgroupsNewsgroupsNewsgroupsChat RoomsChat RoomsChat RoomsChat Rooms

WebWebFoldersFolders

WebWebFoldersFolders

Fax Machine Fax Machine or Computer or Computer Fax/ModemFax/Modem

Fax Machine Fax Machine or Computer or Computer Fax/ModemFax/Modem

VideoVideoConferencingConferencing

VideoVideoConferencingConferencing

FTPFTPFTPFTP

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What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?What are wireless messaging services?

TEXT MESSAGING� Limit messages to usually fewer

than 300 characters� Mobile to Mobile� Mobile to E-Mail� Web to Mobile� Mobile to Provider: use common

Text messagingText messagingallows users to send allows users to send and receive short and receive short

text messages text messages � Mobile to Provider: use common short code – 4 or 5 digit num assigned to specific content or wireless service provider, followed by message – e.g. vote for TV prg contestant

text messages text messages (SMS) on a phone (SMS) on a phone

or PDAor PDA

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PICTURE MESSAGING� Video messaging: to send short video clips (about 15

seconds)� Smart phones & PDAs with picture/video messaging

also called MMS (multimedia message service)� Camera phone, video phone� Camera phone, video phone� Mobile to Mobile� Mobile to E-Mail

Picture messaging Picture messaging allows users to send allows users to send graphics, pictures, graphics, pictures, video clips, sound video clips, sound

files, and short text files, and short text messagesmessages

Video Video messagingmessaging

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WIRELESS INSTANT MESSAGING (IM)�Real-time Internet communications service that allow

wireless mobile devices to exchange messages with one or more mobile devices or online users

�Some WISP provide IM service: smart phone & PDAs can be used to send & receive instant messagesPDAs can be used to send & receive instant messages

�AOL Instant Messenger (AIM), Yahoo! Messenger

�Mobile to Mobile�Mobile to PC�Web to Mobile

Wireless instant Wireless instant messagingmessagingallows allows wireless mobile wireless mobile

devices to exchange devices to exchange messagesmessages

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What are wireless Internet access pointsand cybercafés?� Wireless Internet access

point allows wireless connection to Internet in public location� Hot sport, 3G network

� Cybercaféis coffee house that provides computers with Internet access – some are also hot spots

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What is a global positioning system (GPS)?�Navigation systemconsists of one or more earth-based

receivers that accept & analyze signals sent by satellites in order to determine the geographical location

�GPS receiver: handheld, mountable or embedded device containing an antenna, a radio receiver and a processor –containing an antenna, a radio receiver and a processor –many include screen display showing an individual’s location on a map

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What is a global positioning system (GPS)?

Step 1.GPS satellites orbit Earth. Every thousandth of a second, each satellite sends a signal that

Step 2.A GPS receiver (such as in a car, a wearable device, a smart phone, a handheld device, or a collar)sends a signal that

indicates its current position to the GPS receiver.

or a collar)determines its location on Earth by analyzing at least 3 separate satellite signals from the 24 satellites in orbit.

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What are collaboration and groupware?

� A document management systemprovides for storage and

� Collaboration or work online is working with other users connected to a server

management of a company’s documents

� Groupware is software that allows people work together and share information over a network

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What are voice mailand web services?� Voice mail is voice message

converted to digital form� Web servicesdescribe standardized

software that enables programmers to create applications that to create applications that communicate with other remote computers over the Internet or on an internal business network � doesn’t specific require prg lang,

OS, or Web browser� By sending properly formatted

XML (eXtensive Markup Language)files to Web services

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NETWORKNETWORKNETWORKNETWORK

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NetworksNetworksNetworksNetworks

What is a networknetwork?� Collection of

computers and devicesconnected via communications devicesand transmission mediatransmission media

What are the advantages of using a network?What are the advantages of using a network?

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What is a local area network (LANLAN) and a metropolitan area network (MANMAN) ?� Network in limited geographical area such as

home or office building� Wireless LAN (WLANWLAN)

� Metropolitan area network (MAN) connects LANs � Metropolitan area network (MAN) connects LANs in city or town

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What is a wide area network (WAN)?

� Network that covers large geographic area using many types of mediatypes of media

� Internet is world’s largest WAN

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NETWORK ARCHITECTURESNETWORK ARCHITECTURESNETWORK ARCHITECTURESNETWORK ARCHITECTURES

peer-to-peer &

P2PP2P

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What is a client/server network?� One or more computers

act as serverand other computers, or clients, access serveraccess server

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What is a peer-to-peernetwork?� Simple network

that connects fewer than 10 computerscomputers

� Each computer, or peer, has equal capabilities

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NETWORK TOPOLOGIESNETWORK TOPOLOGIESNETWORK TOPOLOGIESNETWORK TOPOLOGIESbus, ring & star

(layout of devices in network)

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What is a bus network?� All computers and devices connect to central

cable or bus

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What is a ring network?� Cable forms closed

ring, or loop, with all computers and devices arranged along ring

� Data travels from � Data travels from device to device around entire ring, in one direction

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What is a star network?� All devices connect to

a central device (hub or switch)

� All data transferred from one computer to from one computer to another passes through hub or switch

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What is an intranet?

Makes information accessible to employees

Internal network that uses Internet technologies

Extranetallows customers or suppliers to access part of company’s intranet

Typically includes connection to Internet

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IntranetIntranetIntranetIntranet

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NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS NETWORK COMMUNICATIONS

STANDARDSSTANDARDSSTANDARDSSTANDARDSEthernet, Token Ring, TCP/IP, 802.11 (Wi-Fi), Bluetooth,

UWB, IrDA, RFID, WiMAX, WAPUWB, IrDA, RFID, WiMAX, WAP

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Network Communications StandardsNetwork Communications StandardsNetwork Communications StandardsNetwork Communications Standards

What are Ethernet and token ring?

Ethernet technology allows computers to contend for access to network

If two computers send data at same time, a collision occurs and computers must send the data againcomputers must send the data again

Token ring technology controls access to network by requiring devices to pass a special signal,

called token

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What are TCP/IP and 802.11 (Wi-Fi )?� TCP/IP (Transmission Control Protocol/Internet

Protocol) technology transmits data by breaking it up into small pieces, or packets� Commonly used for Internet transmissions

� 802.11 (Wi-Fi) is family of standards for wireless LANs802.11 (Wi-Fi) is family of standards for wireless LANs

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What is Bluetooth?

Short-range radio waves transmitShort-range radio waves transmitdata between Bluetooth devices

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What are UWB, IrDA , RFID, WiMAX , and Wireless Applications Protocol (WAP)?

IrDAIrDAspecification allows data to be transferred wirelessly via infrared

IrDAIrDAspecification allows data to be transferred wirelessly via infrared

Worldwide Interoperability Worldwide Interoperability Worldwide Interoperability Worldwide Interoperability for Microwave Access (WiMAXfor Microwave Access (WiMAX

UWBUWBspecification allows data to be transferred wirelessly via short-range

UWBUWBspecification allows data to be transferred wirelessly via short-range wirelessly via infrared

light waveswirelessly via infrared light waves

Wireless Applications Wireless Applications Protocol (WAP)Protocol (WAP)allow wireless mobile devices to access Internet

Wireless Applications Wireless Applications Protocol (WAP)Protocol (WAP)allow wireless mobile devices to access Internet

Radio Frequency Radio Frequency Identification (RFID)Identification (RFID)uses radio signalsto communicatewith a tagplaced in an object

in a wide area

or 802.16)or 802.16)standard that specifies how wirelessdevices communicate over the airin a wide area

wirelessly via short-rangeradio waveswirelessly via short-rangeradio waves

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Communications SoftwareCommunications SoftwareCommunications SoftwareCommunications Software

What is communications software?

Programs that help users establish connectionto Internet, other network, or another computer Programs that help users

manage transmissionof

System softwareSystem software

Application Application softwaresoftwaremanage transmissionof

data, instructions, and information

Programs that provide an interface for usersto communicate with one another

Application software for communication:e-mail, FTP, Web browser, newsgroup/message boards, chat rooms, instant messaging, video conferencing, Internet telephony,…

softwaresoftware

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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkDial-Up Lines, Dedicated Lines

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Communications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone NetworkCommunications Over the Telephone Network

What is the public switched telephone network (PSTN)?

� Worldwide telephone system that handles voice-oriented telephone callstelephone calls

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What is a dial-up line?� Temporary connectionusing telephone line for

communications� Computers at any two locations can establish a

connection using modems and telephone network

� Costs no more than making regular call� Costs no more than making regular call

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What is a dedicated line?� Always-on connection

between two communications devices

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Dedicated lines:� 5 types:

1.ISDN (Integrated Service Digital Network) line

2.DSL (Digital Subscriber Line), ADSL (Asymmetric …)

3.FTTH & FHHB (Fiber to the Home/Building)

4.T-Carrier line (T1, fractional T1, T3)

5.ATM (Asynchronous Transfer Mode)ISDN line technique of carrying 3 or more

signals at once through the same line

multiplexingmultiplexing

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Communications DevicesCommunications DevicesCommunications DevicesCommunications Devices

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What 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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What is a dial-up modem?� 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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What are ISDN (Integrated Service Digital Network) and DSL (Digital Subscriber Line) modems?

Communications devices that send and receive digital ISDN and DSL signals

Communications devices that send and receive digital ISDN and DSL signalsreceive digital ISDN and DSL signalsreceive 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

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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What is a cable modem?� Sends and receives data

over cable television (CATV) network

� Much faster than dial-up modem or ISDN; speed similar to DSLspeed similar to DSL

� Sometimes called a broadband modem

� Placed after cable splitter� System unit has network

card – e.g. Ethernet card

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What is a wireless modem?

� Allows access to the Web wirelessly from a notebook computer, a PDA, a smart phone, or other mobile deviceother mobile device

� Typically use the same waves used by cellular telephones� Has external or built-in antenna� Available as PC Cards, ExpressCard modules and flash

cards

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What is a network card?� Is an adapter card, PC Card,

ExpressCard module, USB network adapter, or flash cardthat enables computer or device to access networkaccess network

� Coordinates the transmissionand receipt of data, instructions & information to & from the computer or devices containing the network card

� Sometimes called network interface card (NIC)

Wireless network cardWireless network card

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What is a wireless access point?� Central

communications device that allows computers and devices to transfer devices to transfer data wirelessly among themselves or wirelessly to a wired network

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What is a router?� Connects computers and

transmits data to correct destination on network

� Routers forward data on Internet using fastest Internet using fastest available path

� Some routers have a built-in hardware firewall

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What is a hub or switch?� Device that provides central

point for cables in network� Some hubs include routers –

hub receives data from many directions and then forwards it directions and then forwards it to one or more destinations

What are the differences between a hub & a switch & a router?What are the differences between a hub & a switch & a router?

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Home NetworksHome NetworksHome NetworksHome Networks

What is a home network?� Multiple computers

connected in home� Several types of home

networks� Ethernet — connect � Ethernet — connect

computers via cable

� Powerline cable—use electrical lines in house

� Phoneline— use telephone lines

Wireless Home NetworkWireless Home NetworkHomeRF network, Wi-Fi home network

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Communications ChannelCommunications ChannelCommunications ChannelCommunications Channel

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What is a communications channel?� Transmission media on which data travels in

communications system

Bandwidth is amount of data that can travel over a communications

Transmission mediaare materials capable of over a communications

channelare materials capable of carrying one or more signals

Latency is the time it takes a signal to travel from one location to another on a network

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Transmission MediaTransmission MediaTransmission MediaTransmission Media

Transmission media category

Baseband media transmit only one

Broadband media transmit multiple signals transmit only one

signal at a time at much faster speed

Download transfer rates are faster than upload

DSL, cable television Internet service, satellites,…

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How is a request sent over the Internet using a communications channel?

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Transmission MediaTransmission MediaTransmission MediaTransmission Media

Transmission media types

Physical transmission media Wireless transmission mediaPhysical transmission media Wireless transmission media

Twisted-Pair Cable, Coaxial Cable, Fiber Optic Cable

Infrared, Broadcast Radio, Cellular Radio, Microwave

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Physical Transmission MediaPhysical Transmission MediaPhysical Transmission MediaPhysical Transmission Media

What is physical transmission media?

� Wire, cable and other tangible materials used to send communications signals

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What are twisted-pair cableand coaxial cable?� Twisted-pair cableis used for telephone systems and network cabling

(LAN)� Reduced noise– electrical disturbance that can degrade

communication

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What are twisted-pair cableand coaxial cable?� Coaxial cableis often used for cable television wiring – long distance� Single copper wire surrounded by at least 3 layers: an insulation

material, a woven or braided metal, a plastic outer coating

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What is fiber-optic cable?

� Capable of carrying significantly more data at faster speedsthan wire cables

� Less susceptible � Less susceptible to interference (noise) and, therefore, more secure

� Smaller size (thinner and lighter)

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Wireless Transmission MediaWireless Transmission MediaWireless Transmission MediaWireless Transmission Media

What is wireless transmission media?� Used when inconvenient, impractical, or impossible to

install cables� Includes Bluetooth and IrDA

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What are broadcast radioand cellular radio?� Broadcast radiodistributes radio signals over long distances (btw

cities, countries,…)and short distances(within an office or home)- Flexible & portable but slower, more susceptible to noise- used by Bluetooth, UMB, HomeRF, Wi-Fi, and WiMAX* Bluetooth & UMB are alternatives to infrared communications* Hot spots use Wi-Fi & WiMAX networks* Hot spots use Wi-Fi & WiMAX networks

� Cellular radiois form of broadcast radio used for mobile communications – wireless modems & cellular telephones (use high-frequency radio waves to transmit voice & digital data messages)- 1G, 2G & 3G

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What is a microwave station?� Earth-based reflective dishcontains antenna, transceivers

and other equipments for microwave communications� Microwave: radio waves at high-speed signal transmission

(fixed wireless)

� Must be transmitted in � Must be transmitted in straight line with no obstructions

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What is a communications satellite?� Space station that receives microwave

signals from earth-based station, amplifies (strengthens)signals, and broadcasts signals back to any number of earth-based stations(microwave stations, smart phones & GPS)- uplink down link& GPS)- uplink down link

� Air navigation, television and radio broadcast, & Internet connections use communications satellites

� Satellite Internet connection needs a satellite dish & a satellite modem card

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Summary of Communications and NetworksSummary of Communications and NetworksSummary of Communications and NetworksSummary of Communications and Networks

Communications terminology and applications

Communications terminology and applications

Various communications devices, media, and procedures

Various communications devices, media, and procedures

Chapter 7 Complete

How to join computers into a networkHow to join computers into a network

devices, media, and proceduresdevices, media, and procedures

Technology

CSC1100 - Chapter07 - Communications & Networks