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Computers Are Your Future
Twelfth Edition
Chapter 7: Networks: Communicating
and Sharing Resources
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
1
Networks: Communicating
and Sharing Resources
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
2
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).
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
3
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.
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4
Objectives
• Contrast circuit-switching and packetswitching networks and explain their
respective strengths and weaknesses.
• Identify the options, components,
configuration, and maintenance of a
home area network (HAN).
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5
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.
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6
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.
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7
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.
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Network 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
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Network Fundamentals
• LAN
o Uses cables, radio waves, or infrared signals
o Links computers in a limited geographic area
• WAN
o Uses long-distance transmission media
o Links computer systems a few miles or thousands of miles
o Internet is the largest WAN
• MAN
o Designed for a city
o Larger than a LAN, smaller than a WAN
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Network Fundamentals
• CAN
o Several LANs located in various locations on a college
or business campus
o Smaller than a WAN
o Use devices such as switches, hubs, and routers
• PAN
o Network of an individual’s own personal devices
o Usually within a range of 32 feet
o Usually use wireless technology
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Network Fundamentals
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Network Fundamentals
CAN
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PAN
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Network Fundamentals
WAN
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Network 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)
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15
Network Fundamentals
• Node
o Any device connected to a network
• Logical address
o Unique name assigned to each node on the network
• Physical address
o 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 network
o Notebook computers have wireless NICs
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16
Network Fundamentals
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Network Fundamentals
• USB wireless network adapter
o Plugs into a USB port
o Usually provides an intuitive graphical user interface (GUI) for
easy configuration
• USB dongle
o Device inserted into a USB port that
adds additional features to the base
system
Examples: enabling network connectivity
and increasing RAM
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18
Network Fundamentals
• Wireless PC card adapter
o
o
o
o
About the size of a credit card
Inserted into a slot on the side of most notebooks and netbooks
Has built-in WiFi antenna that provides wireless capability
LED lights that indicate whether the computer is connected
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19
Network 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 nodes
o Are similar to routers but work within a single network
• Routers
o Connect two or more networks
o Inspect the source and target of a data package
o Determine the best route to transmit data
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20
Network Fundamentals
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Network Fundamentals
• Wireless access
point (WAP)
o Receives and transmits
radio signals
o Joins wireless nodes to a
wired network
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Network Fundamentals
• Server
o Computer or device with software that manages network
resources, such as files, e-mails, printers, databases
• File server
o Most common type of server
o High-speed computer that provides
program and data files to network users
o 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
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Network Fundamentals
• Network
administrator
o Also called network
engineer
o Installs, maintains,
supports computer
networks
o Interact with users
o Handle security
o Troubleshoot problems
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Advantages and
Disadvantages of Networking
• 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
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Local 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
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Local Area Networks
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Local Area Networks
• Intranet
o Password-protected network
controlled by the company
o Accessed only by employees
• Virtual private
network
o Operates over the Internet
o Accessible by authorized users
for quick access to corporate
information
o Uses secure, encrypted
connections and special
software
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Local 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
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Local Area Networks
• LAN topologies
o 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 occurs
o 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
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Local Area Networks
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Local Area Networks
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Local Area Networks
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Local Area Networks
• LAN technologies
o Ethernet—most-used LAN protocol
• Ethernet star networks
o Most popular versions—use twisted-pair wiring
and switches
• Sends data in a fixed-size unit called a packet
o 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
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Wide 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 lines
o gigaPoP (gigabits per second point of
presence)—transfers data exceeding 1 Gbps (1 billion
bits per second)
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Wide Area Networks
• WAN protocols
o Internet protocols
• Transmission Control Protocol/Internet
Protocol (TCP/IP)
o Protocols that define how the Internet works
• Transmission Control Protocol (TCP)
o Defines how Internet-connected computers
can exchange, control, and confirm messages
• Internet Protocol (IP)
o Provides a distinct identification to any
computer connected to the Internet: the IP
address or Internet address
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Wide Area Networks
• WAN protocols (con’t.)
o Circuit switching
• Used by the public switched telephone network
to send data over a physical end-to-end circuit
• Provides a direct connection between devices
o 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 switching
o Latency—delay introduced when a given packet is
examined by many routers
o Congestion—occurs when the network is overloaded,
causing some packets to be further delayed
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Wide Area Networks
• WAN applications
o E-mail, conferencing, document exchange, remote
database access
o LAN to LAN connections connect two or more
geographically separate locations
o Transaction acquisition—the instant relay of
transaction information from a point-of-purchase
sale.
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Home Networks
• Home Area Networks (HANs)
o Wired home networks
o Wireless home networks
o Hybrid networks
• Combination of wired and wireless technology
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Home Networks
• A Wired Home Network
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Home Networks
• A Wireless Home Network
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Home 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
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Home 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
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Home 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
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Wired and Wireless
Communication
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Moving Data:
Bandwidth and Modems
• Communications
o Process of sending and receiving messages
electronically between two points
o Sending device—initiates the transmission
o Receiving device—accepts the transmission and
responds
• Communications channel
o Path to send and receive messages
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Moving Data:
Bandwidth and Modems
• Analog signals
o Continuous waves
• Digital signals
o Discontinuous, discrete pulses
• Converters
o Translate signals:
• Analog-to-digital converter (ADC)
• Digital-to-analog converter (DAC)
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Moving Data:
Bandwidth and Modems
• Digital signal sampling
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Moving Data:
Bandwidth and Modems
• Bandwidth
o The maximum amount of data transmitted through a
communication channel at one time
• Throughput
o The actual amount of data transmitted
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Moving Data:
Bandwidth and Modems
• Broadband
o Any transmission medium that carries several
channels transporting data at high speeds
• Streaming
o The ability to hear or see content while it is being
downloaded from a Web site
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Moving Data:
Bandwidth and Modems
• Modem
o A communication device used to send and receive
data
o 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.
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Moving Data:
Bandwidth and Modems
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Moving Data:
Bandwidth and Modems
• Types of modems
o
o
o
o
Analog
Digital subscriber line (DSL)
Cable
Integrated Services Digital Network (ISDN)
• Data transfer rate
o Rate at which two modems exchange data
o Measured in bits per second (bps)
• Baud
o Number of signaling elements per second
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Wired Transmission
Media
• Wiring closet
• Houses wiring that supports most types of data
transfer needed
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Wired Transmission
Media
• 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
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Wired Transmission
Media
• Key variations of twisted-wire
pair
o Category 5 (Cat-5)
o Category 5 enhanced (Cat-5e)
o Category 6 (Cat-6)
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Wired Transmission
Media
• Coaxial cable
o Consists of copper wire
surrounded by insulation and
braided wire
• Broadband communication
• Cable TV
• 10 Mbps transfer rate
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Wired Transmission
Media
• Fiber-optic cable
o Consists of thin strands of
glass or plastic that carry
data through pulses of light
• Broadband
communication
• 10 Gbps transfer rate
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Wireless Transmission
Media
• Infrared
o 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
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Wireless Transmission
Media
• Radio transmission
o 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
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Wireless Transmission
Media
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Wireless Transmission
Media
• Microwaves
o Transmit data via
electromagnetic radio
waves with short
frequencies
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Wireless Transmission
Media
• Satellites
o Microwave relay stations in space that transmit data
through microwave signals
o 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
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63
Convergence: Is It a
Phone or a Computer?
• Digitization
o Process of transforming
data into a digital form
• Convergence
o Blending
o Multiple industries
• Examples: Computers,
consumer electronics,
telecommunications
o Products
o Examples: Personal
computers, telephones
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Convergence: Is It A
Phone or A Computer?
• Cellular telephones
o Digital transmission of voice, text, images, and
video
o Classified by generations—4G (fourth
generation)—the current generation
o Cell sites—network of transmitters broadcasts
signals throughout geographic areas called cells
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Convergence: Is It A
Phone or A Computer?
• Each cellular network includes multiple mobile
switching centers (MSCs) that control
communication within a set of cells.
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66
Convergence: Is It A
Phone or A Computer?
• Personal communication service
(PCS)
o Group of digital cellular technologies replacing most
analog cellular services
o 2G (second generation)—used to make
smartphones, with features of phones and
computing devices
o 3G—more data and voice customers and higher data
transfer rates
o 4G—improved connectivity, data transfer rates, and
support for the next generation of multimedia
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67
Convergence: Is It A
Phone or A Computer?
• 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
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Convergence: Is It A
Phone or A Computer?
• 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
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69
Wired and Wireless
Applications
• Internet telephony, or VoIP
(Voice over Internet Protocol)
o Offers computer-to-phone and phone-to-phone
transmission through the Internet
o Placing calls requires:
• Computer with a microphone, speakers or
headphones
• Internet connection
• Telephony-enabled program
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Wired and Wireless
Applications
• Internet telephony
o 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
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71
Wired and Wireless
Applications
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Wired and Wireless
Applications
• 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
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73
Wired and Wireless
Applications
• 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
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74
Wired and Wireless
Applications
• 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
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75
Wired and Wireless
Applications
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Wired and Wireless
Applications
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77
Wired and Wireless
Applications
• Text messaging
(SMS)
o Using cell phone for
applications previously
used on computers
o Instant messaging
o Brief e-mail
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78
Wired and Wireless
Applications
• Picture messaging
o MMS (multimedia messaging system)
o Transmits color pictures and backgrounds
o Cellular telephone acts as a camera
• Location awareness
o Also known as position awareness
o Uses GPS-enabled chips to pinpoint the location of a
cell phone
o Popular with parents of teenagers
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79
Wired and Wireless
Applications
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Summary
• Understand basic networking concepts.
• Distinguish between a WAN, LAN,
MAN, CAN, HAN, and PAN.
• Discuss the advantages and
disadvantages of networks.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
81
Summary
• 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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
82
Summary
• Identify the options, components,
configuration, and maintenance of a
home area network (HAN).
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
83
Summary
• 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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
84
Summary
• 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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
85
Summary
• 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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
86
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permission of the publisher. Printed in the United States of America.
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87