Onlineforms vodafone ie employee advantage

282 CHAPTER 9 Social Computing

Telecommunications and Networking
CHAPTER OUTLINE LEARNING OBJECTIVES
6.1 What Is a Computer Network? 6.1 Compare and contrast the major types of networks.

6.2 Network Fundamentals 6.2 Describe the wireline communications media and transmission

technologies.

6.3 The Internet and the World Wide Web 6.3 Describe the most common methods for accessing the Internet.

6.4 Network Applications: Discovery 6.4 Explain the impact that discovery network applications have had on

business and everyday life.

6.5 Network Applications: 6.5 Explain the impact that communication network applications have Communication had on business and everyday life.

6.6 Network Applications: Collaboration 6.6 Explain the impact that collaboration network applications have

had on business and everyday life.

6.7 Network Applications: Educational 6.7 Explain the impact that educational network applications have had

on business and everyday life.

Opening Case

Can Slack Really Replace E-mail?

E-mail has presented a productivity problem for employees for some time. Over 200 billion e-mail messages are sent and received every day. Employees receive some 122 e-mails per day. Dealing with those e-mails consumes 23 percent of the average employee’s work­ day. In response, an increasing number of organizations are finding that limiting, or even eliminating, e-mail actually increases employee productivity.

MIS

Slack ( www.slack.com ) may provide one answer to the prob­ lems with e-mail. Launched in 2013, Slack is a cloud-based team com­ munication and collaboration software program that helps company

employees communicate in real time. Slack allows different parts of a business to set up different channels for discussions. One channel might be for the information technology group, another for the mar­ keting group, and so on. Anytime someone wants to alert you about something, he or she tags your name to a message. You can follow your colleagues’ exchanges in real time, or you can return to that conversa­ tion later.

Slack offers many features, including chat rooms (called chan­ nels) organized by topic, private groups, and direct messaging. All content inside Slack is searchable, including files, comments, conver­ sations, and people. Channels enable team members to communi­ cate without the use of e-mail or texting. They are open to everyone

CHAPTER 6

158

Introduction 159

in the chat by invitation only. Private channels allow for private conversation between smaller subsets of an original group. Direct messages allow users to send private messages to a specific user rather than to a group of people. Slack is also developing a do-not­ disturb feature. People will not be interrupted by messages between, for example, the hours of 10 P.M. and 8 A.M. If someone sends a mes­ sage to another person during this time, that message will not appear in that colleague’s Slack account until his or her do-not-disturb hours have ended.

Another useful feature of Slack is the Slackbot, a personal soft­ ware assistant that helps users in several ways. Slackbots can:

· Help you complete your account profile and add new apps.

· Answer questions about Slack.

· Answer other questions, such as when a meeting is scheduled or what is for lunch in the company cafeteria.

· Add customized, automatic responses to messages.

· Monitor your e-mail inbox (most companies still use e-mail along with Slack).

Slack has partnered with IBM to develop the next iteration of Slackbot. Slackbot will utilize Watson Conversation, a software tool that helps bots interact through natural language. For example, at the New York Times, Slackbots predict for the newspaper’s editors what stories will perform best with readers on social media.

Slack is growing very rapidly. Since the service appeared, more than 4 million people have become daily users who spend an average of 10 hours each weekday accessing the application. Seventy-seven of the Fortune 100 companies use Slack, as do many technology compa­ nies, including Airbnb, Stripe, Spotify, Salesforce, and BuzzFeed. Com­ panies pay $6.67 to $12.50 per month per user.

Companies use Slack in a variety of ways. For example, at the Weaver Street Market ( www.weaverstreetmarket.coop ), a North Carolina community-owned natural foods grocery, workers use Slack to find out the latest on strawberry shipments, for example. At Hendrick Automotive ( www.hendrickauto.com ), the largest privately held automotive dealership group in the United States, Slack enables employees in Canada and Turkey to stay connected to colleagues at company headquarters in Charlotte, North Carolina.

In June 2016, Slack announced that it was partnering with 12 companies to introduce “message buttons.” The idea is that key func­ tions from outside apps—like using Kayak to search for a flight—can be accomplished from within Slack, with the click of a button. With these message buttons, Slack is competing directly with Facebook, the mar­ ket leader in this technology.

Perhaps as a response to message buttons and perhaps as a re­ sponse to Slack’s rapid growth, in October 2016 Facebook launched its business chat product called Workplace by Facebook. Furthermore, in November 2016 Microsoft launched a rival workplace messaging ser­ vice called Teams.

Slack does present challenges. Consider Slack’s searchable ar­ chive: Most office workers worry that Slack records their every com­ ment and conversation. That process can create problems as workers leave a record of comments that they may regret.

Slack helps text-based communication replace face-to-face in­ teraction. In her book, Reclaiming Conversation: The Power of Talk in a Digital Age, Sherry Turkle cautions against the dangers of this transfor­ mation. She notes that research has found that empathy is lost when we emphasize connectivity over conversation.

Instead of an overflowing e-mail inbox, users can suffer from no­ tification overload. Also, the transition to Slack can cause problems for older employees, who might feel more comfortable with traditional communications channels such as e-mail, telephones, or talking face to face.

Although Slack was designed for organizational communication, people are using Slack to form new communities around common in­ terests. Slack is not as invasive as a Facebook group, where users have to go to a different website. Therefore, while using Slack at work, em­ ployees may be participating in community discussions that are not work-related.

Sources: Compiled from H. Taylor, “Flattered by Microsoft’s Launch of ‘Slack Killer,’” CNBC, November 15, 2016; A. Balakrishnan, “Microsoft Announces Slack Rival, Teams,” CNBC, November 2, 2016; T. Warren, “Slack Shows It’s Worried about Microsoft Teams with a Full-Page Newspaper Ad,” The Verge, November 2, 2016; R. Hackett, “IBM Watson Lends Brains to Slack’s Chatbot,” Fortune, October 26, 2016; R. Hof, “If You Can’t Beat Slack, Here’s How Your Startup Can Join It,” Forbes, August 15, 2016; A. LaFrance, “Slack, the Facebook Slayer,” The Atlantic, June 21, 2016; C. Locke, “Finally, Slack Is Living Up to Its Name,” Wired, June 9, 2016; R. Greenfield, “Slack Consultants Are Bringing

the Chat App to Corporate America,” Bloomberg.com , May 31, 2016; L. Gomes, “10 Breakthrough Technologies 2016: Slack,” MIT Technology Review, 2016;

S. Jacobs, “Email Killer,” Time, November 9, 2015; J. Novet, “Slack Launches User Groups, Hits 1.7M Daily Active Users and 470K Paid Seats,” Venture Beat, October 29, 2015; www.slack.com, accessed November 16, 2016; www.slack

.com, accessed November 15, 2016.

Questions

1. Is it possible for an organization to completely eliminate e-mail through the use of Slack? Why or why not? Support your answer.

2. Why does Slack appear to be more effective for organizational communications than e-mail?

Introduction

In addition to networks being essential in your personal lives, there are three fundamental points about network computing you need to know. First, in modern organizations computers do not work in isolation. Rather, they constantly exchange data with one another. Second, this exchange of data—facilitated by telecommunications technologies—provides companies with a number of very significant advantages. Third, this exchange can take place over any distance and over networks of any size.

Without networks, the computer on your desk would be merely another productivity- enhancement tool, just as the typewriter once was. The power of networks, however, turns

your computer into an amazingly effective tool for accessing information from thousands of sources, thereby making both you and your organization more productive. Regardless of the type of organization (profit/not-for-profit, large/small, global/local) or industry (manufactur­ ing, financial services, healthcare), networks in general, and the Internet in particular, have transformed—and will continue to transform—the way we do business.

Networks support new and innovative ways of doing business, from marketing to supply chain management to customer service to human resources management. In particular, the Internet and private intranets—a network located within a single organization that uses Inter­ net software and TCP/IP protocols—have an enormous impact on our lives, both professionally and personally.

For all organizations regardless of their size, having a telecommunications and networking system is no longer just a source of competitive advantage. Rather, it is necessary for survival.

Computer networks are essential to modern organizations for many reasons. First, net­ worked computer systems enable organizations to become more flexible so that they can adapt to rapidly changing business conditions. Second, networks allow companies to share hardware, computer applications, and data across the organization and among different orga­ nizations. Third, networks make it possible for geographically dispersed employees and work­ groups to share documents, ideas, and creative insights. This sharing encourages teamwork, innovation, and more efficient and effective interactions. Networks are also a critical link be­ tween businesses, their business partners, and their customers.

Clearly, networks are essential tools for modern businesses. But why do you need to be fa­ miliar with networks? The simple fact is that if you operate your own business or work in a busi­ ness, you cannot function without networks. You will need to communicate rapidly with your customers, business partners, suppliers, employees, and colleagues (see the chapter-opening case). Until about 1990, you would have used the postal service or the telephone system with voice or fax capabilities for business communication. Today, however, the pace of business is much faster—almost real time. To keep up with this incredibly fast pace, you will need to use computers, e-mail (see the chapter-opening case), the Internet, smartphones, and other mo­ bile devices. Furthermore, all of these technologies will be connected through networks to en­ able you to communicate, collaborate, and compete on a global scale.

Networking and the Internet are the foundations for commerce in the twenty-first century. Recall that one important objective of this book is to help you become an informed user of information systems. Knowledge of networking is an essential component of modern business literacy. In fact, as you see in IT’s About Business 6.1, a robust telecommunications infrastruc­ ture is essential for entire nations as well.

You begin this chapter by learning what a computer network is and by identifying the various types of networks. You then study network fundamentals, and you next turn your attention to the basics of the Internet and the World Wide Web. You conclude by examining the many network applications available to individuals and organizations—that is, what networks help you do.

What Is a Computer Network?
6.1

A computer network is a system that connects computers and other devices (e.g., printers) through communications media so that data and information can be transmitted among them. Voice and data communication networks are continually becoming faster—that is, their band­ width is increasing—and cheaper. Bandwidth refers to the transmission capacity of a network; it is stated in bits per second. Bandwidth ranges from narrowband (relatively low transmission capacity) to broadband (relatively high network capacity).

The telecommunications industry itself has difficulty defining the term broadband. The Federal Communications Commission’s (FCC) new rules define broadband as the transmission capacity of a communications medium (discussed later in this chapter) faster than 25 megabits per second (Mbps) for download (transmission speed for material coming to you from an Inter­ net server, such as a movie streamed from Netflix) and 4 Mbps for upload (transmission speed for material that you upload to an Internet server such as a Facebook post or YouTube video).

160 CHAPTER 6 Telecommunications and Networking

What Is a Computer Network? 161

IT’s About Business 6.1
The Least Connected Country on Earth
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Eritrea, a nation of six million people, is located in eastern Africa, surrounded by Sudan, Ethiopia, and Djibouti. The country has been ruled by a dictatorship since it achieved independence in 1993. Since 2009, Reporters Without Borders ( www.rsf.org ) has placed Eritrea at the bottom of its press freedom index.

Eritrea is also the world’s most isolated country when it comes to telecommunications access, according to the United Nations In­ ternational Telecommunication Union (ITU; www.itu.int ). Eritre­ ans are allowed to place international phone calls and to use the Internet. However, according to the ITU, only 1 out of 100 Eritreans have a landline, and only 7 in 100 have a cell phone. Both of these proportions are among the lowest around the globe.

The country’s only telecommunications provider, Eritrea Telecommunication Services (EriTel; www.eritel.com.er ), is controlled by the government. Customers must receive approval from local authorities to own a cell phone, and it costs 200 na­ kfa ($13.29) to request permission. Citizens who are performing mandatory military service aren’t given permission to have a cell phone. To activate their phone, customers pay EriTel the equiva­ lent of $33.60. When they add minutes to their phone, that costs a minimum of $3.65 every time. Because the average Eritrean earns roughly $500 a year, this expense is prohibitive to most.

Robert Van Buskirk, a Fulbright scholar from the United States, launched Eritrea’s first informal e-mail service in the mid-1990s. He used international phone calls to send data messages between a computer at the University of Asmara—Eritrea’s capital city—and a computer in California. For a short time, he singlehandedly oper­ ated the entire country’s e-mail service.

As of September 2016, less than 1 percent of Eritreans are on­ line, according to the ITU. Access is available in just a few places. Internet connections are also almost exclusively through dial-up modem, and they are extremely slow. Eritrea was also the last African nation to establish a satellite connection to the Internet. Furthermore, the country is one of only two African coastal nations with no fiber-optic network. Only about 150 landline broadband connections exist, and only a smattering of homes have Internet access, mostly dial-up connections costing about $200 a month.

Eritreans can get public Internet access in about 100 Internet cafes throughout the country. There is often a wait to use one of

about 10 computers in each cafe. Users pay roughly $1.34 to be online for an hour, which costs about the same as seven loaves of bread. Some Internet cafés show American movies and TV shows in the evenings and charge customers to watch.

In October 2016, the government ordered Internet service providers to maintain detailed information on their customers. Other than that, there seems to be little censorship of the Internet. One likely reason is that high costs and long download times have marginalized the use of the Internet as a protest vehicle. Another possible reason is that the country is experiencing severe economic difficulties, and the government may recognize that strengthening the country’s telecommunications would help improve the econ­ omy. The government also wants to improve tourism. This goal would require a greatly improved telecommunications infrastruc­ ture as well.

Sources: Compiled from A. Harnet, “Eritrea Orders Internet Service Providers to Keep Detailed Records of Their Customers,” Eritrea­

beligerance.com , October 6, 2016; B. Bruton, “It’s Bad in Eritrea, But Not That Bad,” New York Times, June 23, 2016; “Areas the Eritrean

Government Should Improve Upon,” Madote.com , February 2, 2016; “Eritrea—Telecoms, Mobile, and Broadband—Statistics and Analy­ ses,” budde.com.au , June 4, 2015; Y. Abselom, “Eritrea Blossoming

Beautifully at 24,” Geeska Afrika Online, May 10, 2015; “Sadly, Eritrea Remains at Tail of All World Indexes,” harnnet.org , January 12, 2015; “Eritrea Telecommunication Report 2015,” Business Monitor Interna­

tional, December 24, 2014; “Eritrea: Stronger Private Sector, Qualified Workforce, International Integration Needed, Says AFDB,” Caperi.com , October 8, 2014; C. Winter and B. Haile, “The World . . . Eritrea,”

Bloomberg BusinessWeek, June 30–July 6, 2014; C. Winter, “Eritrea’s Communications Disconnect,” Bloomberg Business Week, June 26, 2014; R. Atkinson and L. Stewart, “The Economic Benefits of Infor­

mation and Communications Technology,” Information Technology & Innovation Foundation, May 14, 2013.

Questions

1. Describe the impacts of a lack of telecommunications infra­ structure on Eritrea.

2. Besides improving the economy, what other areas of Eritre­ an life would be impacted by a greatly improved telecom­ munications infrastructure?

3. Can the government of Eritrea allow an improved telecom­ munications infrastructure while maintaining strict control over communications and information? Why or why not? Support your answer.

Interestingly, some FCC commissioners feel that the definition of broadband should be 100 Mbps for download. The definition of broadband remains fluid, however, and it will undoubt­ edly continue to change to reflect greater transmission capacities in the future.

You are likely familiar with certain types of broadband connections such as digital sub­ scriber line (DSL) and cable to your homes and dorms. DSL and cable fall within the range of transmission capacity mentioned here and are thus defined as broadband connections.

The various types of computer networks range from small to worldwide. They include (from smallest to largest) personal area networks (PANs), local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), and the ultimate WAN, the Internet. PANs are short-range networks—typically a few meters—that are used for communication among de­ vices close to one person. They can be wired or wireless. (You will learn about wireless PANs in

Chapter 8.) MANs are relatively large computer networks that cover a metropolitan area. MANs fall between LANs and WANs in size. WANs typically cover large geographical areas; in some cases, they can span the entire planet and reach from Earth to Mars and beyond.

Local Area Networks

Regardless of their size, networks represent a compromise among three objectives: speed, dis­ tance, and cost. Organizations typically must select two of the three. To cover long distances, organizations can have fast communication if they are willing to pay for it, or cheap commu­ nication if they are willing to accept slower speeds. A third possible combination of the three trade-offs is fast, cheap communication with distance limitations. This is the idea behind local area networks.

A local area network (LAN) connects two or more devices in a limited geographical re­ gion, usually within the same building, so that every device on the network can communicate with every other device. Most LANs today use Ethernet (discussed later in this chapter). Fig­ ure 6.1 illustrates an Ethernet LAN that consists of four computers, a server, and a printer, all of which connect through a shared cable. Every device in the LAN has a network interface card (NIC) that allows the device to physically connect to the LAN’s communications medium. This medium is typically unshielded twisted-pair wire (UTP).

Although it is not required, many LANs have a file server or network server. The server typically contains various software and data for the network. It also houses the LAN’s network operating system, which manages the server and routes and manages communications on the network.

Wide Area Networks
When businesses have to transmit and receive data beyond the confines of the LAN, they use wide area networks. The term wide area network did not even exist until local area net­ works appeared. Before that time, what we call a wide area network today was simply called a “network.”

A wide area network (WAN) is a network that covers a large geographical area. WANs typically connect multiple LANs. They are generally provided by common carri­ ers such as telephone companies and the international networks of global communi­ cations services providers. Examples of these providers include AT&T ( www.att.com ) in

FIGURE 6.1 Ethernet local area.

the United States, Deutsche Telekom in Germany ( www

.telekom.com ), and NTT Communications ( www.ntt.com ) in Japan.

WANs have large capacities, and they typically combine multiple channels (e.g., fiber-optic cables, microwave, and satellite). WANs also contain routers—a communications processor that routes messages from a LAN to the Internet, across several connected LANs, or across a WAN such as the Internet. The Internet is an example of a WAN.

Enterprise Networks
Organizations today have multiple LANs and may have multi­ ple WANs. All of these networks are interconnected to form an enterprise network. Figure 6.2 displays a model of enterprise computing. Note that the enterprise network in the figure has a backbone network. Corporate backbone networks are

FIGURE 6.2 Enterprise network.

high-speed central networks to which multiple smaller networks (such as LANs and smaller WANs) connect. The LANs are called embedded LANs because they connect to the backbone WAN.

Unfortunately, traditional networks can be rigid and lack the flexibility to keep pace with increasing business networking requirements. The reason for this problem is that the functions of traditional networks are distributed across physical routers and devices (i.e., hardware). This process means that to implement changes, each network device must be configured individu­ ally. In some cases, devices must be configured manually. Software-defined networks (SDN) are an emerging technology that is becoming increasingly important to help organizations manage their data flows across their enterprise networks.

With SDN, decisions controlling how network traffic flows across network devices are man­ aged centrally by software. The software dynamically adjusts data flows to meet business and application needs.

Think of traditional networks as the road system of a city in 1920. Data packets are the cars that travel through the city. A traffic officer (physical network devices) controls each inter­ section and directs traffic by recognizing the turn signals, and size and shape of the vehicles passing through the intersection. The officers can direct only the traffic at their intersection. They do not know the overall traffic volume in the city nor do they know traffic movement across the city. Therefore, it is difficult to control the city’s traffic patterns as a whole and to manage peak-hour traffic. When problems occur, the city must communicate with each indi­ vidual officer by radio.

Now think of SDN as the road system of a modern city. Each traffic officer is replaced by a traffic light and a set of electronic vehicle counters, which are connected to central monitoring and control software. As such, the city’s traffic can be instantly and centrally controlled. The control software can direct traffic differently at various times of the day (say, rush hours). The software monitors traffic flow and automatically changes the traffic lights to help traffic flow through the city with minimal disruption.

Before you go on. . .
1. What are the primary business reasons for using networks?

2. What are the differences between LANs and WANs?

3. Describe an enterprise network.

Network Fundamentals
6.2

In this section, you will learn the basics of how networks actually operate. You begin by study­ ing wireline communications media, which enable computers in a network to transmit and re­ ceive data. You conclude this section by looking at network protocols and types of network processing.

Today, computer networks communicate through digital signals, which are discrete pulses that are either on or off, representing a series of bits (0s and 1s). This quality allows digital sig­ nals to convey information in a binary form that can be interpreted by computers.

The U.S. public telephone system (called the plain old telephone system or POTS) was orig­ inally designed as an analog network to carry voice signals or sounds in an analog wave format. For this type of circuit to carry digital information, that information must be converted into an analog wave pattern by a dial-up modem. Dial-up modems are almost extinct in most parts of the developed world today.

Cable modems are modems that operate over coaxial cable—for example, cable TV. They offer broadband access to the Internet or corporate intranets. Cable modem speeds vary widely. Most providers offer bandwidth between 1 and 6 million bits per second (Mbps) for downloads (from the Internet to a computer) and between 128 and 768 thousand bits per second (Kbps) for uploads. Cable modem services share bandwidth among subscribers in a locality. That is, the same cable line connects to many households. Therefore, when large numbers of neighbors access the Internet at the same time, cable speeds can decrease significantly.

DSL modems operate on the same lines as voice telephones and dial-up modems. DSL mo­ dems always maintain a connection, so an Internet connection is immediately available.

Communications Media and Channels
Communicating data from one location to another requires some form of pathway or medium. A communications channel is such a pathway. It is comprised of two types of media: cable (twisted-pair wire, coaxial cable, or fiber-optic cable) and broadcast (microwave, satellite, ra­ dio, or infrared).

Wireline media or cable media use physical wires or cables to transmit data and infor­ mation. Twisted-pair wire and coaxial cables are made of copper, and fiber-optic cable is made of glass. The alternative is communication over broadcast media or wireless media. The key to mobile communications in today’s rapidly moving society is data transmissions over elec­ tromagnetic media—the “airwaves.” In this section, you will study the three wireline channels. Table 6.1 summarizes the advantages and disadvantages of each of these channels. You will become familiar with wireless media in Chapter 8.

Advantages and Disadvantages of Wireline Communications Channels

TABLE 6.1

Channel

Advantages

Disadvantages

Twisted-pair wire

Inexpensive Widely available

Easy to work with

Slow (low bandwidth) Subject to interference

Easily tapped (low security)

Coaxial cable

Higher bandwidth than twisted-pair

Less susceptible to electromagnetic interference

Relatively expensive and inflexible Easily tapped (low to medium security)

Somewhat difficult to work with

Fiber-optic cable

Very high bandwidth

Relatively inexpensive Difficult to tap (good security)

Difficult to work with (difficult to splice)

166 CHAPTER 6 Telecommunications and Networking

Network Fundamentals 165

Twisted-Pair Wire. The most prevalent form of communications wiring— twisted-pair wire—is used for almost all business telephone wiring. As the name suggests, it consists of strands of copper wire twisted in pairs (see Figure 6.3). Twisted-pair wire is relatively inexpensive to purchase, widely available, and easy to work with. However, it also has some significant disadvantages. Specifically, it is relatively slow for transmitting data, it is subject to interference from other electrical sources, and it can be easily tapped by unintended recipients to gain unauthorized access to data.

Coaxial Cable. Coaxial cable (Figure 6.4) consists of insulated copper wire. Compared with twisted-pair wire, it is much less susceptible to electri­ cal interference, and it can carry much more data. For these reasons, it is com­ monly used to carry high-speed data traffic as well as television signals (thus the

FIGURE 6.3 Twisted-pair wire.

© deepspacedave/iStockphoto

term cable TV). However, coaxial cable is more expensive and more difficult to work with than twisted-pair wire. It is also somewhat inflexible.

Fiber Optics. Fiber-optic cable (Figure 6.5) consists of thousands of very thin filaments of glass fibers that transmit information through pulses of light generated by lasers. The fiber- optic cable is surrounded by cladding, a coating that prevents the light from leaking out of the fiber.

Fiber-optic cables are significantly smaller and lighter than traditional cable media. They also can transmit far more data, and they provide greater security from interference and

FIGURE 6.4 Two views of coaxial cable.

FIGURE 6.5 Two views of fiber-optic cable.

tapping. Fiber-optic cable is typically used as the backbone for a network, whereas twisted- pair wire and coaxial cable connect the backbone to individual devices on the network. In 2016, FASTER, the aptly named 5,600-mile undersea fiber optic cable connecting Japan and the United States became operational. FASTER transmits data at 60 terabits per second across the Pacific Ocean.

Network Protocols
Computing devices that are connected to the network must access and share the network to transmit and receive data. These devices are often referred to as nodes of the network. They work together by adhering to a common set of rules and procedures—known as a protocol— that enable them to communicate with one another. The two major protocols are the Ethernet and Transmission Control Protocol/Internet Protocol.

Ethernet. A common LAN protocol is Ethernet. Many organizations use 100-gigabit Ether­ net, through which the network provides data transmission speeds of 100 gigabits (100 billion bits) per second. The 400-gigabit Ethernet is projected to be in service in 2017.

Transmission Control Protocol/Internet Protocol. The Transmission Con­ trol Protocol/Internet Protocol (TCP/IP) is the protocol of the Internet. TCP/IP uses a suite of protocols, the main ones being the Transmission Control Protocol (TCP) and the Internet Protocol (IP). The TCP performs three basic functions: (1) It manages the movement of data packets (see further on) between computers by establishing a connection between the com­ puters, (2) it sequences the transfer of packets, and (3) it acknowledges the packets that have been transmitted. The Internet Protocol (IP) is responsible for disassembling, delivering, and reassembling the data during transmission.

Before data are transmitted over the Internet, they are divided into small, fixed bundles called packets. The transmission technology that breaks up blocks of text into packets is called packet switching. Each packet carries the information that will help it reach its destination—the sender’s IP address, the intended recipient’s IP address, the number of packets in the message, and the sequence number of the particular packet within the message. Each packet travels independently across the network and can be routed through different paths in the network. When the packets reach their destination, they are reassembled into the original message.

It is important to note that packet-switching networks are reliable and fault tolerant. For example, if a path in the network is very busy or is broken, packets can be dynamically (“on the fly”) rerouted around that path. Also, if one or more packets do not get to the receiving com­ puter, then only those packets need to be re-sent.

Why do organizations use packet switching? The main reason is to achieve reliable end-to­ end message transmission over sometimes-unreliable networks that may have short-acting or long-acting problems.

The packets use the TCP/IP protocol to carry their data. TCP/IP functions in four layers (see Figure 6.6). The application layer enables client application programs to access the other layers, and it defines the protocols that applications use to exchange data. One of these appli­ cation protocols is the Hypertext Transfer Protocol (HTTP), which defines how messages are formulated and how they are interpreted by their receivers. (We discuss hypertext in Section 6.3.) The transport layer provides the application layer with communication and packet ser­ vices. This layer includes TCP and other protocols. The Internet layer is responsible for address­ ing, routing, and packaging data packets. The IP is one of the protocols in this layer. Finally, the network interface layer places packets on, and receives them from, the network medium, which can be any networking technology.

Two computers using TCP/IP can communicate even if they use different hardware and software. Data sent from one computer to another proceed downward through all four layers, beginning with the sending computer’s application layer and going through its network inter­ face layer. After the data reach the receiving computer, they travel up the layers.

FIGURE 6.6 The four layers of the TCP/IP reference model.

TCP/IP enables users to send data across sometimes-unreliable networks with the assur­ ance that the data will arrive in uncorrupted form. TCP/IP is very popular with business orga­ nizations because of its reliability and the ease with which it can support intranets and related functions.

Let’s look at an example of packet switching across the Internet. Figure 6.7 illustrates a message being sent from New York City to Los Angeles over a packet-switching network. Note that the different colored packets travel by different routes to reach their destination in Los Angeles, where they are reassembled into the complete message.

Types of Network Processing
Organizations typically use multiple computer systems across the firm. Distributed processing divides processing work among two or more computers. This process enables computers in dif­ ferent locations to communicate with one another through telecommunications links. A com­ mon type of distributed processing is client/server processing. A special type of client/server processing is peer-to-peer processing.

Client/Server Computing. Client/server computing links two or more comput­ ers in an arrangement in which some machines, called servers, provide computing services for user PCs, called clients. Usually, an organization performs the bulk of its processing or

FIGURE 6.7 Packet switching.

application/data storage on suitably powerful servers that can be accessed by less powerful client machines. The client requests applications, data, or processing from the server, which acts on these requests by “serving” the desired commodity.

Client/server computing leads to the ideas of “fat” clients and “thin” clients. As discussed in Technology Guide 1, fat clients have large storage and processing power and therefore can run local programs (such as Microsoft Office) if the network goes down. In contrast, thin clients may have no local storage and only limited processing power. Thus, they must depend on the network to run applications. For this reason, they are of little value when the network is not functioning.