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Transcript
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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).
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
8
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
9
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
10
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
11
Network Fundamentals
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
12
Network Fundamentals
CAN
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
PAN
13
Network Fundamentals
WAN
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14
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)
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
16
Network Fundamentals
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
17
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
20
Network Fundamentals
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
21
Network Fundamentals
• Wireless access
point (WAP)
o Receives and transmits
radio signals
o Joins wireless nodes to a
wired network
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
22
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
23
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
24
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
25
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
26
Local Area Networks
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
27
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
28
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
29
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
30
Local Area Networks
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
31
Local Area Networks
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
32
Local Area Networks
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
33
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
34
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)
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
35
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
36
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
37
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
38
Home Networks
• Home Area Networks (HANs)
o Wired home networks
o Wireless home networks
o Hybrid networks
• Combination of wired and wireless technology
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
39
Home Networks
• A Wired Home Network
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
40
Home Networks
• A Wireless Home Network
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41
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
42
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
43
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
44
Wired and Wireless
Communication
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
45
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
46
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)
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
47
Moving Data:
Bandwidth and Modems
• Digital signal sampling
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
48
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
49
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
50
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
51
Moving Data:
Bandwidth and Modems
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
52
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
53
Wired Transmission
Media
• Wiring closet
• Houses wiring that supports most types of data
transfer needed
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
54
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
55
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)
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
56
Wired Transmission
Media
• Coaxial cable
o Consists of copper wire
surrounded by insulation and
braided wire
• Broadband communication
• Cable TV
• 10 Mbps transfer rate
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
57
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
58
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
59
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
60
Wireless Transmission
Media
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
61
Wireless Transmission
Media
• Microwaves
o Transmit data via
electromagnetic radio
waves with short
frequencies
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
62
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
64
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
65
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.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
68
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
70
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
71
Wired and Wireless
Applications
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
72
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
75
Wired and Wireless
Applications
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
76
Wired and Wireless
Applications
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
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
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
79
Wired and Wireless
Applications
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
80
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
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted, in any form or by any means, electronic,
mechanical, photocopying, recording, or otherwise, without the prior written
permission of the publisher. Printed in the United States of America.
Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall
87