Chapter 6

Report
Chapter 6
Data Communications
This Could Happen to You: “$175,000 to
Hook Up a Computer?”
Wired vs. Wireless?
What devices are needed?
How much will it cost?
Where to start?
Scenario Video
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6-2
Study Questions
Q1 What is a computer network?
Q2 What are the components of a LAN?
Q3 What are the alternatives for connecting to a WAN?
Q4 What are the fundamental concepts you should know
about the Internet?
Q5
What happens on a typical web server?
Q6
How do organizations benefit from Virtual Private
Networks (VPNs)
How does the knowledge in this chapter help FlexTime and
you?
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Q1: What Is a Computer Network?
Network
• Collection of computers
• Communicate with one another over transmission line
Major types of network topologies
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Q2: What Are the Components of a LAN?
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WANs
Connects
computers across
metropolitan,
state, regional,
national areas
Uses communication
networks from
vendors
Licensed by
government
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Wired Connectivity
Switch
•Special purpose computer that
receives and transmits messages
Gateway
Network interface card (NIC)
UTP (unshielded twisted pair)
Optical fiber cable
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LAN Protocol
IEEE 802.3 Protocol
Wired LAN
IEEE 802.11 Protocol
Wireless LAN
Most popular 802.11g (2010)
10/100/1000 Mbps Ethernet
Bluetooth
Protocol specifies hardware
characteristics, cables, and
how messages are packaged
and processed
Common wireless protocol for
transmitting data over short
distances—wireless mice and
keyboards, cell phones
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Summary of LAN and WAN Networks
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Q3: What Are the Alternatives for a WAN?
WANs connect computers at separate sites
• Use routers and public communications links between sites
• Cable connections made through licensed public
telecommunications companies
Internet service provider (ISP)
• A company that provides customers access to the Internet
• Provides legitimate Internet address
• Serves as gateway to Internet
• You pay for Internet access
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DSL and Cable Internet Access
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DSL Modems
Operates over telephone
lines
Digital
Subscriber
Line (DSL)
Data signals do not
interfere with voice
telephone service
Faster data
transmission than dial-up
256 kbps
to 6.544
Mbps
DSL modems use their
own protocols
Asymmetric digital
subscriber lines (ADSL)
Download and upload
speeds differ
Symmetrical digital
subscriber lines (SDSL)
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Q1: What Is a Computer Network?
Network
• Collection of computers
• Communicate with one another over transmission line
Basic types of Network Topologies
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Cable Modems
Provide high-speed data transmission
Use cable television lines
• High-capacity optical fiber cable to neighborhood
• Optical fiber cable connects to regular cable-television cables
run to subscribers home or business. Does not interfere with
television transmission.
• Up to 500 users share facility
Performance varies based on number of people connected
• Download speed up to 50 Mbps, upload up to 512 kbps
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WAN Wireless Connection
Amazon’s Kindle uses a Sprint wireless network to provide
wireless data connections
Variety of WAN wireless protocols exist. Sprint and Verizon use
EVDO; AT&T supports iPhone and T-Mobile use HSDPA; WiMax by
Clearwire
WAN wireless provides average performance of 500 kbps, with
peaks of up to 1.7 Mbps, as opposed to the typical 50 Mbps for
LAN wireless
Narrowband lines transmission speeds less than 56 kbps
Broadband lines speeds in excess of 256 kbps
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Q4: What Are the Fundamental Concepts
You Should Know About the Internet?
Using the Internet for a
Hotel Reservation
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TCP/IP Architecture
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Application Layer Protocols
Hyper Text Transport Protocol (HTTP)
•Protocol used between browsers and web servers.
Simple Mail Transfer Protocol (SMTP)
•Used for email transmissions.
File Transfer Protocol (FTP)
• Used to move files over Internet.
• Web-Internet-based network of browsers and servers that
process http or https. When you use ftp or smtp, you are
using Internet, not web.
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TCP and IP Protocols
TCP or Transmission Control Protocol
•Breaks traffic up into pieces and send each piece
along its way
IP (Internet Protocol)
• Specifies routing of pieces of data communication
through networks that comprise any Internet
• Packet is a piece of a message that is handled by
programs that implement IP
• Router is a special purpose computer that moves packet
traffic according to rules of IP protocol
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IP Addressing
Public IP Addresses
•Identify a particular device on public Internet
•Public IP Addresses must be unique, worldwide
•Assignment controlled by ICANN (Internet
Corporation for Assigned Names and Numbers)
Private IP Addresses
•Identify a particular device on a private network,
usually on a LAN
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Use of Private IP Addresses
Source: http://www.broadband-help.com/articles/networking/networking-guide-part2-tcpip-explained#b10
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Public IP Addresses and Domain Names
IPv4 Supports (232) or 4,294,967,296 addresses
•Four decimal dotted notation like 165.193.123.253
IPv6 - Supports 2128 addresses
Domain name
•Unique name affiliated
with public IP address
URL (Uniform Resource
Locator)
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box
Sonos is a company leveraging technology to provide
entertainment.
Uses wireless technologies, to develop easily installed, highquality wireless audio systems. Customers hook one of several
different Sonos devices into home LAN device using a wired
Ethernet connection to link up to 32 other Sonos audio devices
around home. Each device can independently play its own music
or other audio; some or all can play same audio program.
Each Sonos device includes a small computer running Linux.
Those computers communicate wirelessly using a proprietary
Sonos protocol.
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box (cont’d)
1. Assume you want to play audio and music in your office,
your living room, and your bedroom.
a. Go to www.Sonos.com and select and price the equipment you will need.
b. Go to Sonos’ competitors at www.LogitechSqueezeBox.com and
http://Soundbridge.Roku.com and select and price equipment you will
need.
c. Recommend one of the selections you identified in your answers to parts a.
and b. and justify your selection.
d. Report your findings to the rest of the class.
2. Visit www.Pandora.com. Using free trial membership, build
a radio station. Base your station on whatever song or
music your group chooses.
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box (cont’d)
3. Sonos equipment does not have on/off switch. You can
mute each station, but to turn a station off, you must
unplug it. Sonos equipment is still on, it will continue
downloading packets over Internet to a device that no
one is listening to.
a. Describe the consequences of this situation on the Internet.
b. You pay a flat fee for your Internet connection. In what ways does
such a fee arrangement discourage efficiency?
c. It turns out that if you pause the music, rather than mute the
device, Sonos device will stop downloading packets. Do you think
this design is appropriate? If not, how would you change it.
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box (cont’d)
4. Using your group’s imagination and curiosity,
describe the consequences of Internet-based audio
on:
a. Existing radio stations
b. Vendors of traditional audio receivers
c. Audio entertainment
d. Cisco (a vendor of Internet routers)
e. Your local ISP
f. Any other companies or entities you believe will be impacted by
wireless audio systems
5. Report your conclusions to the rest of the class.
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box (cont’d)
6. Using history as a guide, we can assume that
audio leads the way for video.
a. Explain how you could use a wireless video system in your new
condo.
b. In the opinion of your group, is having multiple wireless video
players in your condo more or less desirable than wireless
audio? Explain your response.
c. Answer parts a. through f. in step 4, but use wireless video
rather than audio as the driving factor. Report your answers to
the rest of the class.
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Experiencing MIS InClass Exercise 6:
Opening Pandora’s Box (cont’d)
7. Considering all of your answers to steps 1 through 5:
a. What industries are the winners and losers?
b. What companies are the winners and losers?
c. How does your answer to parts a. and b. guide your job
search?
8. Use the knowledge you have gained in answering steps 1
through 6 to prepare a 1-minute statement that you could
make in a job interview about the emerging opportunities in
Internet-based audio and video. Assume that with this
statement you want to demonstrate your ability to think
innovatively.
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Q5 What Happens on a Typical Web Server?
Three-Tier Architecture
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Web Farm Servers
Web
servers
• Programs that run on a server tier
computer
• Manage HTTP traffic by sending and
receiving web pages to and from clients
Commerce
servers
• Application programs that run on a
server tier computer
• Receives requests from users via web
server, takes some action, and returns a
response to users via the web server
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Hypertext Markup Language (HTML)
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XML, Flash, Silverlight, HTML 5
XML (eXtensible
Markup
Language)
•Fixes several HTML
deficiencies
•Program-to-program
interaction over web
Flash and
Silverlight
•Add-ons to browsers
•Provides animation,
movies, other advanced
graphics inside a browser
HTML 5.0
•New version of HTML
supports animation,
movies, and graphics
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Q6 How Do Organizations Benefit From
Virtual Private Networks (VPNs)
Virtual private network
• Uses Internet or private network to create appearance of
point-to-point connections
• Uses public Internet to create appearance of private network
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WAN Using VPN Remote Access Using VPN;
Actual Connections
Remote Client
(Apparent connection)
Actual connections
(P2P leased lines)
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How Does the Knowledge in This Chapter
Help FlexTime and You?
Owners have to make decisions about data
communications equipment for new building.
Decisions fraught with risk. With knowledge, better
chance of making good decisions.
Kelly has no data communications knowledge,
she cannot be a good partner.
With knowledge in this chapter, you’re on road to
having knowledge like Neil, and not being a
passive bystander like Kelly.
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Ethics Guide: Personal Email at Work
Scenario A
• You email 12 pictures of your surfing skills from New Zealand to
a friend who works at some company in Ohio.
• Each picture is 6.2 megabytes in size.
• Packets of email and picture transmitted to Ohio company
router and from router to its email server. Your message
consumed processing cycles on router and email serve. A copy
of your pictures stored on that email server until your friend
deletes them.
• Friend uses company LAN to download the pictures to his
desktop computer.
• Friend reads his email during his working hours.
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Scenario A Questions
Is it ethical for you to send the email and picture to your friend at
work?
Does your answer to question 1 change depending on size of pictures?
Does your answer change if you send 100 pictures? If you send 1,000
pictures? If your answer does change, where do you draw the line?
Once pictures are stored on company’s email server, who owns
pictures? Who controls those pictures? Does Ohio company have right
to inspect contents of its employees’ mailboxes? If so, what should
managers do when they find your picture that has absolutely nothing to
do with company’s business?
What is greater cost to your friend’s company: Cost of infrastructure to
transmit and store your email or cost of time your friend takes at work
to read and view your pictures? Does this consideration change any of
your answers above?
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Ethics Guide: Personal Email at Work
Scenario B
Update: 2008: You use Facebook page with the photos. Friend use
company computer to view your Facebook page.
Scenario C
Update: 2010: from his phone or iPad to view your Facebook page.
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Questions for Scenarios B and C
How does 2008 update change ethics of situation? Is it ethical
for your friend to read and update Facebook using company’s
computers?
How does 2010 update change ethics of situation? Is it any of
company’s business what your friend does with his iPhone or
other device at work?
Describe a reasonable policy for computer/phone/
communicating device use at work. Consider email, Facebook,
and Twitter as well as 2008 and 2010 updates. Endeavor to
develop a policy that will be robust in likely data communication
changes in future.
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Guide: Thinking Exponentially Is Not
Possible, But…
Nathan Myhrvold claimed that humans:
• One cannot think exponentially
• Think of fastest linear change and extrapolate from there
Was writing about growth of magnetic storage
Applies to growth of computer network phenomena
Ubiquitous and cheap connectivity is growing
exponentially
• What are the threats and opportunities?
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Guide: Thinking Exponentially Is Not
Possible, But…(cont’d)
Social progress occurs in small, evolutionary, adaptive
steps
Technology doesn’t drive people to do new things (?)
Technology may enable a capability, but people may not
want it
• People want to do what they are doing more easily
• They want to solve existing problems
Respond by hedging your bets
The more time involved, the more potential for error
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Active Review
Q1
What is a computer network?
Q2
What are the components of a LAN?
Q3
What are the alternatives for connecting to a WAN?
Q4
What are the fundamental concepts you should know
about the Internet?
Q5
What happens on a typical web server?
Q6
How do organizations benefit from Virtual Private
Networks (VPNs)
How does the knowledge in this chapter help FlexTime and
you?
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Case Study 6: Keeping Up with Wireless
Substantial portions of the knowledge you gain from this chapter
will be obsolete within the first 5 years of your career.
What is the problem of the last mile? The bottleneck on data
communications into homes, and into smaller businesses, is the
last mile.
Problem with optical fiber infrastructure—it cannot be used by
mobile devices
WiMax standard includes two usage models: Fixed and mobile.
Former akin to LAN wireless in existence today; latter for mobile
access.
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Case Study 6: Keeping Up with Wireless
(cont’d)
December 1, 2008, Clearwire merged with Sprint Nextel
and received a $3.2 billion outside investment. Clearwire
gained access to Sprint Nextel’s spectrum holdings
Products are
marketed as
Sprint Xohm
•List five possible commercial applications
for mobile WiMax. Consider applications
that necessitate mobility.
•Select the three most promising
applications and justify your selection.
•Explain why Clearwire share price has
dropped since 2007.
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Case Study 6: Keeping Up with Wireless
(cont’d)
Search the web for LTE vs. WiMax comparisons
and compare and contrast these two
technologies.
Where will this end? On which of these
technologies would you be willing to invest $100
million? Why?
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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

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