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c81e728d9d4c-0 | TABLE OF CONTENTS
COVER
TITLE PAGE
COPYRIGHT
DEDICATION
ABOUT THE AUTHORS
PREFACE
PURPOSE OF THIS BOOK
WHAT’S NEW IN THIS EDITION
LAB EXERCISES
ONLINE SUPPLEMENTS FOR INSTRUCTORS
E-BOOK
ACKNOWLEDGMENTS
PART ONE: INTRODUCTION
CHAPTER 1: INTRODUCTION TO DATA COMMUNICATIONS
1.1 INTRODUCTION
1.2 DATA COMMUNICATIONS NETWORK... | Page 2 | Chapter 1 |
37693cfc7480-0 | HANDS-ON ACTIVITY 2A
HANDS-ON ACTIVITY 2B
CHAPTER 3: PHYSICAL LAYER
3.1 INTRODUCTION
3.2 CIRCUITS
3.3 COMMUNICATION MEDIA
3.4 DIGITAL TRANSMISSION OF DIGITAL DATA
3.5 ANALOG TRANSMISSION OF DIGITAL DATA
3.6 DIGITAL TRANSMISSION OF ANALOG DATA
3.7 IMPLICATIONS FOR CYBER SECURITY
SUMMARY
KEY TERMS
QUESTIONS
EXERCISES
MIN... | Page 3 | Chapter 3 |
289dff07669d-0 | EXERCISES
MINICASES
TECH UPDATES
HANDS-ON ACTIVITY 5A
HANDS-ON ACTIVITY 5B
HANDS-ON ACTIVITY 5C
HANDS-ON ACTIVITY 5D
HANDS-ON ACTIVITY 5E
HANDS-ON ACTIVITY 5F
PART THREE: NETWORK TECHNOLOGIES
CHAPTER 6: NETWORK DESIGN
6.1 INTRODUCTION
6.2 NEEDS ANALYSIS
6.3 TECHNOLOGY DESIGN
6.4 COST ASSESSMENT
6.5 IMPLICATIONS FOR CYB... | Page 4 | Chapter 6 |
81b073de9370-0 | 8.4 VIRTUAL LANS
8.5 THE BEST PRACTICE BACKBONE DESIGN
8.6 IMPROVING BACKBONE PERFORMANCE
8.7 IMPLICATIONS FOR CYBER SECURITY
SUMMARY
KEY TERMS
QUESTIONS
EXERCISES
MINICASES
TECH UPDATES
HANDS-ON ACTIVITY 8A
HANDS-ON ACTIVITY 8B
CHAPTER 9: WIDE AREA NETWORKS
9.1 INTRODUCTION
9.2 DEDICATED-CIRCUIT NETWORKS
9.3 PACKET-SW... | Page 5 | Chapter 9 |
adcaec3805aa-0 | HANDS-ON ACTIVITY 10C
PART FOUR: NETWORK MANAGEMENT
CHAPTER 11: NETWORK SECURITY
11.1 INTRODUCTION
11.2 RISK ASSESSMENT
11.3 ENSURING BUSINESS CONTINUITY
11.4 INTRUSION PREVENTION
11.5 BEST PRACTICE RECOMMENDATIONS
11.6 IMPLICATIONS FOR YOUR CYBER SECURITY
SUMMARY
KEY TERMS
QUESTIONS
EXERCISES
MINICASES
TECH UPDATES
HA... | Page 6 | Chapter 11 |
508df4cb2f4d-0 | FIGURE 1-3 Network architecture components
FIGURE 1-4 Network models. OSI = Open Systems Interconnection Reference
FIGURE 1-5 Message transmission using layers. IP = Internet Protocol; HTTP =...
FIGURE 1-6 Some common data communications standards. HTML = Hypertext Marku...
FIGURE 1-7 A security robot on the IOT
FIGURE... | Page 7 | Chapter 11 |
95525872e442-1 | FIGURE 2-17 Desktop videoconferencing
FIGURE 2-18 Viewing the SMTP packet header
FIGURE 2-19 Viewing the source of the SMTP packet
FIGURE 2-20 SMTP packets in Wireshark
FIGURE 2-21 POP packets in Wireshark
Chapter 3
FIGURE 3-1 Point-to-point circuit
FIGURE 3-2 Multipoint circuit
FIGURE 3-3 Simplex, half-duplex, and ful... | Page 7 | Chapter 11 |
bb0f169a5947-0 | FIGURE 3-10 Binary numbers used to represent different characters using ASCI...
FIGURE 3-11 Parallel transmission of an 8-bit code
FIGURE 3-12 Serial transmission of an 8-bit code
FIGURE 3-13 Unipolar, bipolar, and Manchester signals (digital)
FIGURE 3-14 Sound wave
FIGURE 3-15 Amplitude modulation
FIGURE 3-16 Frequenc... | Page 8 | Chapter 11 |
6c4628b734cd-1 | FIGURE 4-12 Analyzing packets with Wireshark
Chapter 5
FIGURE 5-1 Message transmission using layers. SMTP = Simple Mail Transfer Pr...
FIGURE 5-2 Transmission Control Protocol (TCP) segment. ACK = Acknowledgment...
FIGURE 5-3 Internet Protocol (IP) packet (version 4). CRC = Cyclical Redunda...
FIGURE 5-4 Internet Proto... | Page 8 | Chapter 11 |
c68f3a4055bc-0 | FIGURE 5-9 IPv4 public address space
FIGURE 5-10 IPv4 private address space
FIGURE 5-11 Address subnets
FIGURE 5-12 How the DNS system works?
FIGURE 5-13 A small corporate network
FIGURE 5-14 Sample routing tables
FIGURE 5-15 Routing on the Internet with Border Gateway Protocol (BGP), Open...
FIGURE 5-16 Anatomy of a r... | Page 9 | Chapter 11 |
ac3b73049879-1 | FIGURE 7-11 The data center at Indiana University
FIGURE 7-12 Network with load balancer
FIGURE 7-13 The storage area network (SAN) at the Kelley School of Business ...
FIGURE 7-14 SOHO LAN designs
FIGURE 7-15 Powerline adapter
FIGURE 7-17 TracePlus
FIGURE 7-18 WLANs in a neighborhood in Bloomington, Indiana | Page 9 | Chapter 11 |
59c299cb0aee-0 | FIGURE 7-19 WLANs at Indiana University
FIGURE 7-20 Plans for Floors 3–8 of Apollo Residence
FIGURE 7-21 LAN equipment price list
Chapter 8
FIGURE 8-1 Rack-mounted switched backbone network architecture
FIGURE 8-2 An MDF with rack-mounted equipment. A layer 2 chassis switch with...
FIGURE 8-3 MDF network diagram. MDF =... | Page 10 | Chapter 11 |
729c70f33509-1 | FIGURE 9-9 A virtual private network (VPN)
FIGURE 9-10 Using VPN software. Shaded area depicts encrypted packets
FIGURE 9-11 WAN services
FIGURE 9-14 100 Gbps network for a U.S. Internet service provider
FIGURE 9-15 Starting Wireshark
FIGURE 9-16 Viewing encrypted packets
FIGURE 9-17 Packets that enter the VPN tunnel
F... | Page 10 | Chapter 11 |
c8c7bdfbbab7-0 | FIGURE 10-2 Basic Internet architecture. ISP = Internet service provider; IX...
FIGURE 10-3 A typical Internet backbone of a major ISP
FIGURE 10-4 DSL architecture. DSL = digital subscriber line; ISP = Internet ...
FIGURE 10-5 Some typical digital subscriber line data rates
FIGURE 10-6 Cable modem architecture. ISP = I... | Page 11 | Chapter 11 |
26d79f8d1b5b-1 | FIGURE 11-23 Starting the encryption
FIGURE 11-24 System Preferences for a Mac
FIGURE 11-25 Searching system preferences
FIGURE 11-26 Security & Privacy: FileVault
FIGURE 11-27 PGP key generator
FIGURE 11-28 PGP encryption
FIGURE 11-29 PGP decryption
FIGURE 11-30 Selecting a recipient of an encrypted message
FIGURE 11-... | Page 11 | Chapter 11 |
617332afd17b-0 | FIGURE 12-3 Network with load balancer
FIGURE 12-4 Capacity management software
FIGURE 12-5 Network with content engine
FIGURE 12-6 Network with content delivery
FIGURE 12-7 Network configuration diagram
FIGURE 12-8 Part of the Network Operations Center at Indiana University
FIGURE 12-9 Network traffic versus network m... | Page 12 | Chapter 11 |
d7c4e61be700-0 | Business Data Communications and Networking
Fourteenth Edition
Jerry FitzGerald
Jerry FitzGerald & Associates
Alan Dennis
Indiana University
Alexandra Durcikova
University of Oklahoma | Page 13 | Chapter 11 |
5ea438bb2205-0 | VP AND EDITORIAL DIRECTOR
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ea28d914bcc6-2 | ISBN 9781119702665 (epub)
Subjects: LCSH: Data transmission systems. | Computer networks. | Office practice–Automation.
Classification: LCC TK5105 .F577 2021 (print) | LCC TK5105 (ebook) | DDC 004.6–dc23
LC record available at https://lccn.loc.gov/2020028461
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... | Page 14 | Chapter 11 |
2ede479f4a85-0 | To my son Alec,
Alan
To all curious minds who want to know how today’s modern world works.
Alexandra | Page 15 | Chapter 11 |
4bbed9fe1c0c-0 | ABOUT THE AUTHORS
Alan Dennis is a Fellow of the Association for Information Systems and a professor of information
systems in the Kelley School of Business at Indiana University. He holds the John T. Chambers Chair in
Internet Systems, which was established to honor John Chambers, president and chief executive officer... | Page 16 | Chapter 11 |
d3c2826a5fd3-1 | Systems, the U.S. Department of Defense, and the Australian Army.
Alexandra Durcikova is an Associate Professor at the Price College of Business, University of Oklahoma.
Alexandra has a PhD in management information systems from the University of Pittsburgh. She has
earned an MSc degree in solid state physics from Come... | Page 16 | Chapter 11 |
75ca7225c221-0 | PREFACE
The field of data communications has grown faster and become more important than computer
processing itself. Though they go hand in hand, the ability to communicate and connect with other
computers and mobile devices is what makes or breaks a business today. There are three trends that
support this notion. Firs... | Page 17 | Chapter 11 |
1a77dd76cf0c-1 | This book has two intended audiences. First and foremost, it is a university textbook. Each chapter
introduces, describes, and then summarizes fundamental concepts and applications. Management Focus
boxes highlight key issues and describe how networks are actually being used today. Technical Focus
boxes highlight key t... | Page 17 | Chapter 11 |
71dc7c223102-2 | from the topics discussed in the chapter, we also introduce Tech Updates. We draw implications that focus
on improving the management of networks and information systems as well as implications for cyber
security of an individual and an organization. Tech Updates offer two cybersecurity topics per chapter that | Page 17 | Chapter 11 |
5049ab7b3718-0 | help students to expand their knowledge of cybersecurity and see how it relates to the material covered in
the chapter.
Second, we have revised Chapter 2 to use a new framework for application architecture that includes
application services.
Third, we have revised the WAN chapter (Chapter 9) to include the rapidly chan... | Page 18 | Chapter 11 |
0e76b4a4b586-1 | Bloomington, Indiana
www.kelley.indiana.edu/ardennis
Alexandra Durcikova
Norman, Oklahoma
http://www.ou.edu/price/mis/people/alexandra_durcikova.html | Page 18 | Chapter 11 |
6150ca05e1f0-0 | PART ONE INTRODUCTION | Page 19 | Chapter 11 |
923d0b06c1d8-0 | CHAPTER 1
INTRODUCTION TO DATA COMMUNICATIONS
This chapter introduces the basic concepts of data communications. It describes why it is important to
study data communications, how data communications fit within the discipline of Management
Information Systems (MIS), and introduces you to the three fundamental questions... | Page 20 | Chapter 11 |
04c54b563141-0 | 1.1 INTRODUCTION
What Internet connection should you use? Cable modem or DSL (formally called Digital Subscriber Line)?
Cable modems are supposedly faster than DSL, providing data speeds of 50 Mbps to DSL’s 1.5–25 Mbps
(million bits per second). One cable company used a tortoise to represent DSL in advertisements. So
w... | Page 21 | Chapter 11 |
de6c8e705aa4-1 | messaging, and exchange of data between different devices). These interactions are possible because of
technologies such as cloud, big data, big data analytics, and the Internet of Things. But the technology that
enables all these technologies to communicate is the high-speed data communication network, that is, the
In... | Page 21 | Chapter 11 |
fdb6a1f8ed7d-2 | America.
This book answers three fundamental questions.
First, how does the Internet work? When you access a website using your computer, laptop, iPad, or
smartphone, what happens so that the page opens in your Web browser? This is the focus in Chapters 1–5.
The short answer is that the software on your computer (or an... | Page 21 | Chapter 11 |
f534a39fb39a-0 | you requested. You might have heard a news story that the U.S. or Chinese government can read your
email or see what websites you’re visiting. A more shocking truth is that the person sitting next you at a
coffee shop might be doing exactly the same thing—reading all the packets that come from or go to your
laptop. How... | Page 22 | Chapter 11 |
3cc44403b6ef-1 | spend way more on network management and security each year than we spend to buy the computer in
the first place. And that’s for well-run networks; poorly run networks cost a lot more. Many people think
network security is a technical problem, and, to some extent, it is. However, the things people do and
don’t do cause... | Page 22 | Chapter 11 |
5ab3bb1fc6be-2 | such as: What is our bestselling product? Which regions bring in the most revenue? Which regions
are losing money? These decisions are made using the data stored in databases. Data is retrieved
from a database and imported to a software like Excel, Tableau, or PowerBI so that these business
questions can be answered us... | Page 22 | Chapter 11 |
50751c6b5812-0 | FIGURE 1-1 What is MIS?
In order for the IT strategy to implement the core capabilities, data communications and networking
infrastructure must be available. You are using this infrastructure anytime you use the Internet on your
laptop and even your cell phone. MIS core capabilities and the IT strategy rest on a solid ... | Page 23 | Chapter 11 |
8b0d9893a51e-0 | With a few years of experience, there is the possibility to work as an information systems manager,
for which the median annual pay is as high as $117,780. An information systems manager plans,
coordinates, and directs IT-related activities in such a way that they can fully support the goals of
any business. Thus, this... | Page 24 | Chapter 11 |
f389bb799a30-1 | electrical or optical transmission systems. Such systems are often called data communications networks.
This is in contrast to the broader term telecommunications, which includes the transmission of voice and
video (images and graphics) as well as data and usually implies longer distances. In general, data
communicatio... | Page 24 | Chapter 11 |
b469db1ca758-0 | As networks in other countries were connected to the Internet, they were assigned their own domain
names. Some international domain names are as follows:
CA for Canada
AU for Australia
UK for the United Kingdom
DE for Germany
New top-level domains that focus on specific types of businesses continue to be introduced, su... | Page 25 | Chapter 11 |
bd68910041d3-1 | that perform special functions such as switches and routers.
Strictly speaking, a network does not need a server. Some networks are designed to connect a set of
similar computers that share their data and software with each other. Such networks are called peer-to-
peer networks because the computers function as equals,... | Page 25 | Chapter 11 |
4049247d344e-0 | FIGURE 1-2 Example of a local area network (LAN)
FIGURE 1-3 Network architecture components
There are three computers that make networks what they are. These are the client, the server, and the
router. The client initiates a communication with the server by sending a request to the server. Once the
server receives the ... | Page 26 | Chapter 11 |
1a2b13dc5b74-0 | connection possible.
All three devices are computers, and their hardware is pretty much the same—they have a motherboard
with CPU (central processing unit), memory, and some storage space. However, only the client had a
screen, keyboard, and mouse. Why? Are the server and router less deserving? No. Their purpose is not... | Page 27 | Chapter 11 |
2069ae518ff2-1 | clearly defined small area, such as one floor or work area, a single building, or a group of buildings. The
upper-left diagram in Figure 1-3 shows a small LAN located in the records building at the former
McClellan Air Force Base in Sacramento. LANs support high-speed data transmission compared with
standard telephone ... | Page 27 | Chapter 11 |
e11d2f5775f6-2 | technologies as the Internet (e.g., Web servers, Java, HTML [Hypertext Markup Language]) but is open to
only those inside the organization. For example, although some pages on a Web server may be open to the
public and accessible by anyone on the Internet, some pages may be on an intranet and therefore hidden
from thos... | Page 27 | Chapter 11 |
62afdd3e5d40-0 | 1.3 NETWORK MODELS
There are many ways to describe and analyze data communications networks. All networks provide the
same basic functions to transfer a message from sender to receiver, but each network can use different
network hardware and software to provide these functions. All of these hardware and software produc... | Page 28 | Chapter 11 |
630066a855b1-1 | communications. In 1984, this effort produced the OSI model.
The OSI model is the most talked about and most referred to network model. If you choose a career in
networking, questions about the OSI model will be on the network certification exams offered by
Microsoft, Cisco, and other vendors of network hardware and so... | Page 28 | Chapter 11 |
7a734b999759-2 | messages so the succeeding layers are shielded from transmission errors. Thus, layer 2 performs error
detection and correction. It also decides when a device can transmit so that two computers do not try to
transmit at the same time. We say, that data link layer has a local responsibility. | Page 28 | Chapter 11 |
1c0fb952ef95-0 | FIGURE 1-4 Network models. OSI = Open Systems Interconnection Reference
Layer 3: Network Layer
The network layer performs routing. It determines the next computer to which the message should be
sent, so it can follow the best route through the network and finds the full address for that computer if
needed.
Layer 4: Tra... | Page 29 | Chapter 11 |
2b0ee964b6c8-1 | compression, translation between different data formats, and screen formatting. Any function (except
those in layers 1 through 5) that is requested sufficiently often to warrant finding a general solution is
placed in the presentation layer, although some of these functions can be performed by separate hardware
and sof... | Page 29 | Chapter 11 |
39b301c0b527-0 | utilities for application programs. Each user program determines the set of messages and any action it
might take on receipt of a message. Other network-specific applications at this layer include network
monitoring and network management.
1.3.2 Internet Model
The network model that dominates current hardware and softw... | Page 30 | Chapter 11 |
8a1d1b2a718f-1 | when to transmit messages over the media. Second, it formats the messages by indicating where they start
and end. Third, it detects and may correct any errors that have occurred during transmission. Chapter 4
discusses the data link layer in detail.
Layer 3: The Network Layer
The network layer in the Internet model per... | Page 30 | Chapter 11 |
1f354ca1c507-0 | The layers in the Internet are often so closely coupled that decisions in one layer impose certain
requirements on other layers. The data link layer and the physical layer are closely tied together because
the data link layer controls the physical layer in terms of when the physical layer can transmit. Because
these tw... | Page 31 | Chapter 11 |
1ad761bd9b41-1 | the Internet.
FIGURE 1-5 Message transmission using layers. IP = Internet Protocol; HTTP = Hypertext Transfer
Protocol; TCP = Transmission Control Protocol | Page 31 | Chapter 11 |
bf550c38aed9-0 | Application Layer
First, the user creates a message at the application layer using a Web browser by clicking on a link (e.g.,
get the home page at www.somebody.com). The browser translates the user’s message (the click on the
Web link) into HTTP. The rules of HTTP define a specific PDU—called an HTTP packet—that all We... | Page 32 | Chapter 11 |
ff6dbeb754fa-1 | which, in turn, contains the HTTP packet, which, in turn, contains the message, to the data link layer.
Data Link Layer
If you are connecting to the Internet using a LAN, your data link layer may use a protocol called Ethernet,
which also has its own rules and PDUs. The data link layer formats the message with start an... | Page 32 | Chapter 11 |
e72693efdc9b-2 | The application layer (i.e., the Web server) reads the HTTP packet and the message it contains (the
request for the Web page) and processes it by generating an HTTP packet containing the Web page you
requested. Then the process starts again as the page is sent back to you.
The Pros and Cons of Using Layers
There are th... | Page 32 | Chapter 11 |
e35107a1af15-0 | encapsulation, because the PDU at a higher level is placed inside the PDU at a lower level so that the
lower-level PDU encapsulates the higher-level one. The major advantage of using different software and
protocols is that it is easy to develop new software, because all one has to do is write software for one level
at... | Page 33 | Chapter 11 |
70f7b9080072-1 | sent (thus increasing the time it takes to transmit), and the different software packages increase the
processing power needed in computers. Because the protocols are used at different layers and are stacked
on top of one another (take another look at Figure 1-5), the set of software used to understand the
different pr... | Page 33 | Chapter 11 |
2a235f6608c8-2 | IP), for data link layer software (e.g., Ethernet IEEE 802.3), and for physical hardware (e.g., V.90
modems). De jure standards typically take several years to develop, during which time technology
changes, making them less useful.
De facto standards are those that emerge in the marketplace and are supported by several... | Page 33 | Chapter 11 |
74fc8a44cb98-0 | The de jure standardization process has three stages: specification, identification of choices, and
acceptance. The specification stage consists of developing a nomenclature and identifying the problems to
be addressed. In the identification of choices stage, those working on the standard identify the various
solutions... | Page 34 | Chapter 11 |
ce4fdeaeb561-1 | 1,000 members from both public and private organizations in the United States. ANSI is a standardization
organization, not a standards-making body, in that it accepts standards developed by other organizations
and publishes them as American standards. Its role is to coordinate the development of voluntary national
stan... | Page 34 | Chapter 11 |
b19e9d9531d8-0 | Usually, several vendors adopt the proposed standard and develop products based on it. Once at
least two vendors have developed hardware or software based on it and it has proven successful in
operation, the proposed standard is changed to a draft standard. This is usually the final
specification, although some protoco... | Page 35 | Chapter 11 |
5c0efe87405c-1 | networking information. Search engines can help you find them. A good initial starting point is the
telecom glossary at http://www.atis.org. Three other useful sites are http://www.zdnet.com,
http://www.networkcomputing.com, and http://www.zdnet.com.
Third, there are many useful magazines that discuss computer technolo... | Page 35 | Chapter 11 |
d70ea1d79d1c-0 | FIGURE 1-6 Some common data communications standards. HTML = Hypertext Markup Language;
HTTP = Hypertext Transfer Protocol; IMAP = Internet Message Access Protocol; IP = Internet Protocol;
LAN = Local Area Network; MPEG = Motion Picture Experts Group; POP = Post Office Protocol; TCP =
Transmission Control Protocol
Inst... | Page 36 | Chapter 11 |
6be45f861a0b-0 | a good understanding of each of these. Figure 1-6 provides a brief road map for some of the important
communication technologies we discuss in this book.
For now, there is one important message you should understand from Figure 1-6: For a network to
operate, many different standards must be used simultaneously. The sen... | Page 37 | Chapter 11 |
e7a87890302a-1 | Another important problem is security. Employees bring these devices to work so that they can access not
only their email but also other critical company assets, such as information about their clients, suppliers,
or sales. Employers face myriad decisions about how to manage access to company applications for
BYOD. Com... | Page 37 | Chapter 11 |
f33910b95e52-2 | communications, with phones plugged into computers or directly into the LAN using Voice over Internet
Protocol (VoIP). Vonage and Skype have taken this one step further and offer telephone service over the
Internet at dramatically lower prices than traditional separate landline phones, whether from traditional
phones o... | Page 37 | Chapter 11 |
5d885c517b3e-0 | this interaction between IoT devices will happen seamlessly, without human intervention. And you might
already be asking Alexa or Siri for advice on where to eat, lock, and unlock your apartment, turn on/off
your lights, or change the thermostat setting. For this to happen, Alexa/Siri must be able to communicate
with y... | Page 38 | Chapter 11 |
f9384d5af2ed-0 | FIGURE 1-7 A security robot on the IOT
IoT technologies are not restricted to consumer use. To the contrary, they are used in many places such as
manufacturing, process automation, decision analytics, and smart electrical grids. However, the
underlying principle of all the applications is that IoT devices are connected... | Page 39 | Chapter 11 |
750b039d2ba8-0 | Ten years ago, network managers would never have thought about the need to manage robots over their
networks.
1.5.3 Massively Online
You have probably heard of massively multiplayer online games, such as World of Warcraft, where you
can play with thousands of players in real time. Well, today not only games are massive... | Page 40 | Chapter 11 |
48d7fbe44cac-1 | good use in education, politics, and activism. Only the future will show what humanity can do with what
massively online has to offer.
What these three trends have in common is that there will be an increasing demand for professionals who
understand development of data communications and networking infrastructure to su... | Page 40 | Chapter 11 |
5e1f3b505f6b-2 | Second, today’s networking environment requires that a wide variety of devices could connect. Employees’
use of their own devices under BYOD policies increases security risks, as does the move to the IoT. Several
security experts say that IoT doesn’t stand for Internet of Things; it stands for Internet of Targets.
Indi... | Page 40 | Chapter 11 |
efd4bae3d1a6-0 | information we generate will open new market opportunities. Today, Google has almost a million Web
servers (see Figure 1-8). If we assume that each server costs an average of $1,000, the money large
companies spend on storage is close to $1 billion. Capital expenditure of this scale is then increased by
money spent on ... | Page 41 | Chapter 11 |
3e082cbb1a3c-1 | addresses the message and determines its route through the network. The data link layer formats the
message to indicate where it starts and ends, decides when to transmit it over the physical media, and
detects and corrects any errors that occur in transmission. The physical layer is the physical
connection between the... | Page 41 | Chapter 11 |
dfa25c05f8bb-0 | physical layer, adds a Protocol Data Unit (PDU) to the message.
Standards Standards ensure that hardware and software produced by different vendors can work
together. A de jure standard is developed by an official industry or a government body. De facto
standards are those that emerge in the marketplace and are support... | Page 42 | Chapter 11 |
c28fb3d815ce-0 | OSI model
peer-to-peer networks
physical layer
Protocol Data Unit (PDU)
protocol stack
protocol
Request for Comment (RFC)
router
server
Standards
switch
transport layer
Web server
wide area networks (WANs)
wireless access point
QUESTIONS
1. How can data communications networks affect businesses?
2. How do data communic... | Page 43 | Chapter 11 |
276ca8d04908-0 | continue? What are the implications for those who design and operate networks?
21. The number of standardized protocols in use at the application layer has significantly increased since
the 1980s. Why? Do you think this trend will continue? What are the implications for those who
design and operate networks?
22. How ma... | Page 44 | Chapter 11 |
fbb74639092f-1 | the RFC stage.
H. Discuss how the revolution/evolution of communications and networking is likely to affect how you
will work and live in the future.
I. Investigate the pros and cons of developing native apps versus taking a browser-based approach.
MINICASES
I. Global Consultants John Adams is the chief information off... | Page 44 | Chapter 11 |
2301b83dea36-0 | they would have (e.g., LANs, BNs, WANs) and where they are likely to be located. (2) What types of
standard protocols and technologies do you think they are using at each layer (e.g., see Figures 1-3
and 1-5)?
III. Consolidated Supplies Consolidated Supplies is a medium-sized distributor of restaurant supplies
that ope... | Page 45 | Chapter 11 |
d5a98a96f82d-1 | by telephone through a traditional catalog. She has read about the convergence of voice and data and
is wondering about changing her current traditional, separate, and rather expensive telephone and
data services into one service offered by a new company that will supply both telephone and data over
her Internet connec... | Page 45 | Chapter 11 |
e9ebe5e71d2f-2 | 3. Main players—these could be people, processes, software, hardware, etc.
4. How it works—use lot of pictures and be as technical as possible; create this part as a tutorial so that
your audience can follow along | Page 45 | Chapter 11 |
0781c1dc936c-0 | 5. How does it relate to material covered in class so far (and in the future)
6. Additional material/books/links where to learn more about this topic
7. Credits
8. List of References
9. Memo addressed to your professor describing all of the above information
HANDS-ON ACTIVITY 1A
Internet as We Know It Today
We think ab... | Page 46 | Chapter 11 |
76fc8cf02723-1 | standard that most professional and education institutions use today. It is used for network
troubleshooting, network analysis, software and communications protocol development, and general
education about how networks work.
Wireshark enables you to see all messages sent by your computer, as well as some or all of the ... | Page 46 | Chapter 11 |
7256ff20eac9-0 | 5. You will see results similar to those in Figure 1-9. There are three windows below the tool bar:
a. The top window is the Packet List. Each line represents a single message or packet that was
captured by Wireshark. Different types of packets will have different colors. For example, HTTP
packets are colored green. De... | Page 47 | Chapter 11 |
e1cce0645035-1 | inside it.
Deliverables
1. List the PDU at layers 2, 3, and 4 that were used to transmit your HTTP GET packet.
a. Locate your HTTP GET packet in the Packet List and click on it.
b. Look in the Packet Detail window to get the PDU information.
2. How many different HTTP GET packets were sent by your browser? Not all the ... | Page 47 | Chapter 11 |
cd928447495f-0 | 3. List at least five other protocols that Wireshark displayed in the Packet List window. You will need to
clear the filter by clicking on the “Clear” icon that is on the right of the Filter toolbar. | Page 48 | Chapter 11 |
cd17c1d7da51-0 | PART TWO FUNDAMENTAL CONCEPTS | Page 49 | Chapter 11 |
09c04aba2d66-0 | CHAPTER 2
APPLICATION LAYER
The application layer (also called layer 5) is the software that enables the user to perform useful work. The
software at the application layer is the reason for having the network because it is this software that
provides the business value. This chapter focuses on the four fundamental type... | Page 50 | Chapter 11 |
4b3b20b723c2-0 | 2.1 INTRODUCTION
Network applications are the software packages that run in the application layer. You should be quite
familiar with many types of network software, because it is these application packages that you use when
you use the network. In many respects, the only reason for having a network is to enable these
a... | Page 51 | Chapter 11 |
4b6a393a2034-1 | means database queries in SQL (structured query language). The third function is the application logic
(sometimes called business logic), which also can be simple or complex, depending on the application.
The fourth function is the presentation logic (sometimes called the user interface), the presentation of
informatio... | Page 51 | Chapter 11 |
29d92f559e2e-2 | Because of this, the most frequently used software as a service (SaaS) is email. For example,
many universities have moved to this model for their students. | Page 51 | Chapter 11 |
8f1eaa221720-0 | Community cloud This deployment model is used by organizations that have a common
purpose. Rather than each organization creating its own private cloud, organizations decide to
collaborate and pool their resources. Although this cloud is not private, only a limited number of
companies have access to it. Community cloud... | Page 52 | Chapter 11 |
1e59e3a77dff-1 | work is shared between the servers and clients. In cloud-based architectures, the cloud provides services
(software, platform, and/or infrastructure) to the client. Although the client–server architecture is the
dominant application architecture, cloud-based architecture is becoming the runner-up because it
offers rapi... | Page 52 | Chapter 11 |
b863f3e76138-0 | FIGURE 2-1 Host-based architecture
2.2.2 Client-Based Architectures
In the late 1980s, there was an explosion in the use of personal computers. Today, more than 90% of most
organizations’ total computer processing power now resides on personal computers, not in centralized
mainframe computers. Part of this expansion wa... | Page 53 | Chapter 11 |
00c20cc8eb52-1 | insurance. All the data in the database (or all the indices) must travel from the server where the database
is stored over the network circuit to the client, which then examines each record to see if it matches the
data requested by the user. This can overload the network circuits because far more data are transmitted
... | Page 53 | Chapter 11 |
b24435aeb2ed-0 | be split between both.
Figure 2-3 shows one example, with the presentation logic and application logic on the client, and services
logic, application logic, data access logic and data storage on the server. In this case, the client software
accepts user requests and performs the application logic that produces database... | Page 54 | Chapter 11 |
c4a206255238-0 | vendors to be used together. But this is also one of their disadvantages, because it can be difficult to get
software from different vendors to work together. One solution to this problem is middleware, software
that sits between the application software on the client and the application software on the server.
Middlew... | Page 55 | Chapter 11 |
7c5fc8ce47c7-1 | and the client, the application and presentation. This is called a two-tier architecture, because it uses
only two sets of computers, one set of clients and one set of servers.
A three-tier architecture uses three sets of computers, as shown in Figure 2-4. In this case, the
software on the client computer is responsibl... | Page 55 | Chapter 11 |
a5603135c084-0 | FIGURE 2-4 Three-tier thin client client–server architecture
FIGURE 2-5 The n-tier thin client client–server architecture
The primary advantage of an n-tier client–server architecture compared with a two-tier architecture (or a
three-tier compared with a two-tier) is that it separates the processing that occurs to bett... | Page 56 | Chapter 11 |
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