Chapter 6 Data Communications. Wired vs. Wireless? What devices are needed? How much will it cost?...

Chapter 6

Data Communications

Wired vs. Wireless?

What devices are needed?

How much will it cost?

Where to start?

This Could Happen to You: “$175,000 to Hook Up a Computer?”

6-2

Scenario Video

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

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?

Study Questions

6-3Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall

Q1: What Is a Computer Network?


Q2: What Are the Components of a LAN?


Connects computers

across metropolitan,

state, regional, national areas

Uses communication networks from

vendors

Licensed by government

WANs


Switch•Special purpose computer that receives and transmits messages

GatewayNetwork interface card (NIC)UTP (unshielded twisted pair)Optical fiber cable

Wired Connectivity


LAN Protocol

6-8

IEEE 802.11 Protocol


IEEE 802.3 Protocol

Summary of LAN and WAN Networks


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

Q3: What Are the Alternatives for a WAN?


DSL and Cable Internet Access


DSL Modems


Network• Collection of computers • Communicate with one another over

transmission lineBasic types of Network Topologies

Q1: What Is a Computer Network?


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 facilityPerformance varies based on number of people

connected• Download speed up to 50 Mbps, upload up to 512

kbps

Cable Modems


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 wirelessNarrowband lines transmission speeds less than 56 kbps

Broadband lines speeds in excess of 256 kbps

WAN Wireless Connection


Using the Internet for a Hotel Reservation

Q4: What Are the Fundamental Concepts You Should Know About the Internet?


TCP/IP Architecture


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.

Application Layer 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

TCP and IP Protocols


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

IP Addressing


Use of Private IP Addresses


Source: http://www.broadband-help.com/articles/networking/networking-guide-part2-tcpip-explained#b10

IPv4 Supports (232) or 4,294,967,296 addresses • Four decimal dotted notation like

165.193.123.253IPv6 - Supports 2128 addresses

Public IP Addresses and Domain Names


Sonos is a company leveraging technology to provide entertainment.

Uses wireless technologies, to develop easily installed, high-quality 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.

Experiencing MIS InClass Exercise 6: Opening Pandora’s Box


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.

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.



4. Using your group’s imagination and curiosity, describe the consequences of Internet-based audio on:

a. Existing radio stationsb. Vendors of traditional audio receiversc. Audio entertainmentd. Cisco (a vendor of Internet routers)e. Your local ISPf. Any other companies or entities you believe will be

impacted by wireless audio systems

5. Report your conclusions to the rest of the class.



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.



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.



Q5 What Happens on a Typical Web Server?

6-29

Three-Tier Architecture


• Programs that run on a server tier computer

• Manage HTTP traffic by sending and receiving web pages to and from clients

Web 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

Commerce

servers

Web Farm Servers


Hypertext Markup Language (HTML)


XML (eXtensible Markup Language) Flash and Silverlight

HTML 5.0

XML, Flash, Silverlight, HTML 5


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

Q6 How Do Organizations Benefit From Virtual Private Networks (VPNs)


WAN Using VPN Remote Access Using VPN; Actual Connections


Remote Client (Apparent

connection)

Actual connections (P2P leased lines)

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.

How Does the Knowledge in This Chapter Help FlexTime and You?


Ethics Guide: Personal Email at Work


Scenario A Questions


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.

Ethics Guide: Personal Email at Work


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.

Questions for Scenarios B and C


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?

Guide: Thinking Exponentially Is Not Possible, But…


Social progress occurs in small, evolutionary, adaptive stepsTechnology 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 problemsRespond by hedging your bets

The more time involved, the more potential for error

Guide: Thinking Exponentially Is Not Possible, But…(cont’d)


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?

Active Review


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.

Case Study 6: Keeping Up with Wireless


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

•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.

Products are marketed as Sprint Xohm

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?

Case Study 6: Keeping Up with Wireless (cont’d)


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.


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Chapter 6 Data Communications. Wired vs. Wireless? What devices are needed? How much will it cost?...

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