Computers Are Your Future Twelfth Edition Chapter 7: Networks: Communicating and Sharing Resources Copyright © 2012 Pearson Education, Inc. Publishing

Computers Are Your FutureComputers Are Your FutureTwelfth EditionTwelfth Edition

Chapter 7: Networks: Communicatingand Sharing Resources

Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 1

Networks: CommunicatingNetworks: Communicatingand Sharing Resourcesand Sharing Resources


Objectives Objectives • Understand basic networking

concepts.• Distinguish between a WAN, LAN,

MAN, CAN, HAN, and PAN.• Discuss the advantages and

disadvantages of networks.• Distinguish between peer-to-peer,

client/server, and virtual private local area networks (LANs).


Objectives Objectives • Define topology and understand

how the three LAN topologies differ.• Explain the importance of network

protocols.• Name the most widely used LAN

protocol and their versions.• Identify the special components of a

wide area network (WAN) that differentiate it from a LAN.


Objectives Objectives • Contrast circuit-switching and

packet-switching networks and explain their respective strengths and weaknesses.

• Identify the options, components, configuration, and maintenance of a home area network (HAN).


Objectives Objectives • Differentiate between bandwidth

and throughput, and discuss the bandwidth needs of typical users.

• Discuss how modems transform digital computer signals into analog signals and analog into digital.

• List various physical and wireless transmission media and explain several transmission methods.


Objectives Objectives • Explain the limitations of the public

switched telephone network (PSTN) for sending and receiving computer data.

• Describe digital telephony and multiplexing, including their impact on line usage.

• Discuss last-mile technologies that connect users with their communication providers.


Objectives Objectives • Provide examples of how

digitization and convergence are blurring the boundaries that distinguish popular communications devices, including phones and computers.

• Discuss various wired and wireless applications.


Network FundamentalsNetwork Fundamentals• Networks

o Links multiple computer systems and enables them to share data and resources

o Types of computer networks:• Local area network (LAN)• Wide area network (WAN)• Metropolitan area network (MAN)• Campus area network (CAN)• Personal area network (PAN


Network FundamentalsNetwork Fundamentals• LAN

o Uses cables, radio waves, or infrared signalso Links computers in a limited geographic area

• WAN o Uses long-distance transmission mediao Links computer systems a few miles or thousands of

mileso Internet is the largest WAN

• MANo Designed for a cityo Larger than a LAN, smaller than a WAN


Network FundamentalsNetwork Fundamentals• CAN

o Several LANs located in various locations on a college or business campus

o Smaller than a WANo Use devices such as switches, hubs, and routers

• PANo Network of an individual’s own personal deviceso Usually within a range of 32 feeto Usually use wireless technology


Network FundamentalsNetwork Fundamentals


Network Network FundamentalsFundamentalsCAN PAN


Network Network FundamentalsFundamentalsWAN


Network FundamentalsNetwork Fundamentals• Communication devices

o Convert data into signals to travel over a medium

• Computers• Modems• Routers• Switches• Hubs• Wireless access points• Network interface cards (NICs)


Network FundamentalsNetwork Fundamentals• Node

o Any device connected to a network

• Logical addresso Unique name assigned to each node on the network

• Physical addresso Unique numeric that identifies each node on the

network built into the hardware

• Network interface card (NIC)o Expansion board or adapter that provides a

connection between the computer and the networko Notebook computers have wireless NICs




Network FundamentalsNetwork Fundamentals• USB wireless network adapter

o Plugs into a USB porto Usually provides an intuitive graphical user interface

(GUI) for easy configuration

• USB dongleo Device inserted into a USB port that adds additional features to the base system

Examples: enabling network connectivity and increasing RAM


Network Network FundamentalsFundamentals

• Wireless PC card adaptero About the size of a credit cardo Inserted into a slot on the side of most notebooks and

netbookso Has built-in WiFi antenna that provides wireless

capabilityo LED lights that indicate whether the computer is

connected


Network FundamentalsNetwork Fundamentals• Hub

o Joins multiple computers together in a single network

o Does not manage traffic between the connections

• Switches o Filter and forward data between nodeso Are similar to routers but work within a single

network

• Routers o Connect two or more networkso Inspect the source and target of a data packageo Determine the best route to transmit data


Network Network FundamentalsFundamentals



• Wireless access point (WAP)o Receives and transmits

radio signalso Joins wireless nodes to a

wired network


Network FundamentalsNetwork Fundamentals• Server

o Computer or device with software that manages network resources, such as files, e-mails, printers, databases

• File servero Most common type of servero High-speed computer that provides program and data files to network userso Contains the network operating system (NOS)

• File directories for file and resource location on the LAN

• Automated distribution of software updates to desktop computers on the WAN

• Internet services support• Protection of services and data• Access to connected hardware by authorized users


Network FundamentalsNetwork Fundamentals• Network

administratoro Also called network

engineero Installs, maintains,

supports computer networks

o Interact with users o Handle securityo Troubleshoot problems


Advantages andAdvantages andDisadvantages of Disadvantages of

NetworkingNetworking• Networking

o Advantages• Reduced hardware costs• Application sharing• Sharing information resources• Data management centralization• Connecting people

o Disadvantages• Loss of autonomy• Lack of privacy• Security threats• Loss of productivity


Local Area NetworksLocal Area Networks• Wireless LAN

o Connects users through radio waves instead of wires

o Use includes networks in:• Homes• Hospitals• Colleges

o Secured with a radio transmission technique that spreads signals over a seemingly random series of frequencies.

o Effective inside range of between 125 and 300 feet


Local Area NetworksLocal Area Networks


• Intraneto Password-protected

network controlled by the company

o Accessed only by employees

• Virtual private networko Operates over the Interneto Accessible by authorized

users for quick access to corporate information

o Uses secure, encrypted connections and special software



Local Area NetworksLocal Area Networks• LAN topologies

o Network topology• Physical design of a LAN

o Topology resolves contention—conflict that occurs when two or more computers on the network attempt to transmit at the same time

o Contention sometimes results in collisions—corruption of network data caused when two computers transmit at the same time


• LAN topologieso Bus topology

• Practical for home or small office• One node transmits at a time• Terminators signify the end of the circuit• Uses contention management—technique that

specifies what happens when a collision occurso Star topology

• For office buildings, computer labs, and WANs• Easy to add users

o Ring topology• For a division of a company or one floor• Not in common use today• Node can transmit only when it has the token—

special unit of data that travels around the ring









Local Area NetworksLocal Area Networks• LAN technologies

o Ethernet—most-used LAN protocol• Ethernet star networks

oMost popular versions—use twisted-pair wiring and switches

• Sends data in a fixed-size unit called a packeto WiFi

• Uses radio waves to provide a wireless LAN standard at Ethernet speeds

• Needs a central access point—could be a wireless router

• Hot spots—public wireless access locations


Wide Area NetworksWide Area Networks• Point of presence (POP)

o WAN connection point used to obtain access to the WAN

o Wired or wireless

• Backbones o High-capacity WAN transmission lineso gigaPoP (gigabits per second point of

presence)—transfers data exceeding 1 Gbps (1 billion bits per second)


Wide Area NetworksWide Area Networks• WAN protocols

o Internet protocols• Transmission Control Protocol/Internet

Protocol (TCP/IP)oProtocols that define how the Internet

works• Transmission Control Protocol (TCP)

oDefines how Internet-connected computers can exchange, control, and confirm messages

• Internet Protocol (IP) oProvides a distinct identification to any

computer connected to the Internet: the IP address or Internet address


• WAN protocols (con’t.)o Circuit switching

• Used by the public switched telephone networkto send data over a physical end-to-end circuit

• Provides a direct connection between deviceso Packet switching

• Used for computer communication• Divides and sends outgoing messages as packets,

which are reassembled on receipt• More efficient and less expensive than circuit

switchingo Latency—delay introduced when a given packet is

examined by many routerso Congestion—occurs when the network is overloaded,

causing some packets to be further delayed

Wide Area NetworksWide Area Networks


Wide Area NetworksWide Area Networks

• WAN applicationso E-mail, conferencing, document exchange,

remote database accesso LAN to LAN connections connect two or more

geographically separate locationso Transaction acquisition—the instant relay of

transaction information from a point-of-purchase sale.


Home NetworksHome Networks• Home Area Networks (HANs)

o Wired home networkso Wireless home networkso Hybrid networks

• Combination of wired and wireless technology


Home NetworksHome Networks• A Wired Home Network


Home NetworksHome Networks• A Wireless Home Network


Home NetworksHome Networks• Setting up a home network

o Planning• Select technology • Purchase equipment and firewall software

o Configuring a wired network• Connect each computer to the router• Plug printer, scanner, etc., into a computer


Home NetworksHome Networks• Setting up a home network

(con’t.)o Configuring a wireless network

• Connect each node to wireless router with a wireless adapter

• Connect DSL or cable modem to wireless router

o Maintenance and support• Minimal maintenance required• Unplug power source from router and other

peripherals and restart computer to correct problems


Home NetworksHome Networks• Future of home networking

o Convergence will allow you to use home networks to

• Control household appliances• Protect homes with security systems• Manage home network events through

central control units in new homes• Utilize wireless systems• Control entertainment, temperature

regulation, and lighting


Wired and Wireless Wired and Wireless CommunicationCommunication


Moving Data: Moving Data: Bandwidth and ModemsBandwidth and Modems

• Communicationso Process of sending and receiving messages

electronically between two pointso Sending device—initiates the transmissiono Receiving device—accepts the transmission

and responds

• Communications channelo Path to send and receive messages



• Analog signalso Continuous waves

• Digital signalso Discontinuous, discrete pulses

• Converterso Translate signals:

• Analog-to-digital converter (ADC)• Digital-to-analog converter (DAC)


Moving Data:Moving Data:Bandwidth and ModemsBandwidth and Modems

• Digital signal sampling



• Bandwidtho The maximum amount of data transmitted

through a communication channel at one time

• Throughputo The actual amount of data transmitted



• Broadbando Any transmission medium that carries several

channels transporting data at high speeds

• Streamingo The ability to hear or see content while it is

being downloaded from a Web site



• Modemo A communication device used to send and

receive datao The term modem comes from modulate and

demodulate.• The sender uses modulation to transmit

digital signals.• The receiver uses demodulation to return

signals to digital form.





• Types of modemso Analogo Digital subscriber line (DSL)o Cableo Integrated Services Digital Network (ISDN)

• Data transfer rateo Rate at which two modems exchange datao Measured in bits per second (bps)

• Baudo Number of signaling elements per second


Wired TransmissionWired TransmissionMediaMedia

• Wiring closet• Houses wiring that supports most types of

data transfer needed



• Twisted-pair wire• Copper wire used for

telephone and data communication

o Two pairs of interweaved wires twisted together

o Inexpensive, but bandwidth too low for video, voice, and data at the same time



• Key variations of twisted-wire pairo Category 5 (Cat-5)o Category 5 enhanced (Cat-5e)o Category 6 (Cat-6)



• Coaxial cableo Consists of copper wire

surrounded by insulation and braided wire

• Broadband communication

• Cable TV• 10 Mbps transfer rate



• Fiber-optic cableo Consists of thin strands

of glass or plastic that carry data through pulses of light

• Broadband communication

• 10 Gbps transfer rate


Wireless TransmissionWireless TransmissionMediaMedia

• Infraredo Wireless transmission

medium that carries data through the air using light beams

o Sending and receiving devices must be in line of sight

o Uses an IrDA port to enable data transfer



• Radio transmissiono Enables music, photos, and voice to travel

through the air as radio frequency or radio waves

o Bluetooth—radio transmission enables devices within 30 feet to communicate wirelessly

o Does not require direct line of sight





• Microwaveso Transmit data via

electromagnetic radio waves with short frequencies



• Satelliteso Microwave relay stations in space that

transmit data through microwave signalso Direct broadcast satellite (DBS)—

consumer satellite technology that receives digital TV signals through a reception dish

o Requires the computer system to have a special communications device called a network access point—sends and receives data between computer that contain wireless adapters


Convergence: Is It aConvergence: Is It aPhone or a Computer?Phone or a Computer?

• Digitizationo Process of

transforming data into a digital form

• Convergenceo Blendingo Multiple industries

• Examples: Computers, consumer electronics, telecommunications

o Productso Examples: Personal

computers, telephonesCopyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall 64

• Cellular telephoneso Digital transmission of voice, text, images,

and videoo Classified by generations—4G (fourth

generation)—the current generationo Cell sites—network of transmitters

broadcasts signals throughout geographic areas called cells

Convergence: Is It AConvergence: Is It APhone or A Computer?Phone or A Computer?


• Each cellular network includes multiple mobile switching centers (MSCs) that control communication within a set of cells.



• Personal communication service (PCS)oGroup of digital cellular technologies replacing

most analog cellular serviceso2G (second generation)—used to make

smartphones, with features of phones and computing devices

o3G—more data and voice customers and higher data transfer rates

o4G—improved connectivity, data transfer rates, and support for the next generation of multimedia



• Web-enabled devices o Display and respond to

markup languages• Examples: HTML, XML

—used to build Web pages

o Examples• PDAs • Smartphones—

replacing PDAs• Notebooks



• WAP (Wireless Application Protocol)o Standard—specifies how users can access

the Web securely using:• Pagers• Smartphones• PDAs• Other wireless devices

o Requires a microbrowser



Wired and Wireless Wired and Wireless ApplicationsApplications

• Internet telephony, or VoIP (Voice over Internet Protocol) o Offers computer-to-phone and phone-to-phone

transmission through the Interneto Placing calls requires:

• Computer with a microphone, speakers or headphones

• Internet connection• Telephony-enabled program



• Internet telephonyo Videoconferencing (Web conferencing)—

transmits sound and video images using:• Video camera (Webcams)• Skype software

o Whiteboards—enable participants to create a shared workspace

o Webcams—inexpensive, low-resolution analog or digital video cameras

o Internet TV—ability to view television shows, videos, and movies over the Internet





• Facsimile transmission (fax)o Transmits documents over a telephone line

or the Internet using either:• Standalone fax machine• Computer with a fax modem and a

scanner



• Satellite technology o Satellite radio

• Not affected by location, distance, or obstructions

• Uses satellites orbiting the Earth• Permits usage in areas with restricted local

radio stations or poor AM/FM reception



• Satellite technology (con’t.) o GPS (Global Positioning System)

• System of 27 satellites allowing a receiver to pinpoint locations

• Mobile units for cars• Installed car systems







• Text messaging (SMS)o Using cell phone for

applications previously used on computers

o Instant messagingo Brief e-mail



• Picture messaging o MMS (multimedia messaging system)o Transmits color pictures and backgrounds o Cellular telephone acts as a camera

• Location awarenesso Also known as position awarenesso Uses GPS-enabled chips to pinpoint the

location of a cell phoneo Popular with parents of teenagers




SummarySummary• Understand basic networking

concepts.• Distinguish between a WAN, LAN,

MAN, CAN, HAN, and PAN.• Discuss the advantages and

disadvantages of networks.


SummarySummary• Define topology and understand

how the three LAN topologies differ.• Explain the importance of network

protocols.• Identify the special components of a

wide area network (WAN) that differentiate it from a LAN.


SummarySummary• Identify the options, components,

configuration, and maintenance of a home area network (HAN).


SummarySummary• Differentiate between bandwidth

and throughput, and discuss the bandwidth needs of typical users.

• Discuss how modems transform digital computer signals into analog signals and analog into digital.

• List various physical and wireless transmission media and explain several transmission methods.


SummarySummary• Explain the limitations of the public

switched telephone network (PSTN) for sending and receiving computer data.

• Describe digital telephony and multiplexing, including their impact on line usage.

• Discuss last-mile technologies that connect users with their communication providers.


SummarySummary• Provide examples of how

digitization and convergence are blurring the boundaries that distinguish popular communications devices, including phones and computers.

• Discuss various wired and wireless applications.


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Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall

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Computers Are Your Future Twelfth Edition Chapter 7: Networks: Communicating and Sharing Resources Copyright © 2012 Pearson Education, Inc. Publishing