Copyright John Wiley & Sons Canada

Copyright John Wiley & Sons Canada
CHAPTER 4 Networks Copyright John Wiley & Sons Canada

Chapter 4: Networks 4.1 What Is a Computer Network? 4.2 Network Fundamentals 4.3 The Internet and the World Wide Web 4.4 Internet Network Applications Copyright John Wiley & Sons Canada

LEARNING OBJECTIVES Define the term “computer network”, and compare and contrast the two major types of networks. Describe the differences among the three types of wireline communications media, and discuss the main advantages and disadvantages of each type. Copyright John Wiley & Sons Canada

LEARNING OBJECTIVES (CONTINUED)
Differentiate between the Internet and the World Wide Web, and identify the most common methods for accessing the Internet. Identify six major categories of network applications, provide an example of each, and explain how that application supports business functions. Copyright John Wiley & Sons Canada

OPENING CASE 4.1 THE NETWORK NEUTRALITY WARS
The Problem The CEO of Netflix was asked whether the Internet’s infrastructure can withstand the strain of his expanding business, which had more than 36 million subscribers worldwide as of mid He replied: “If there’s anything you’d want to bet on, it’s that technology will make bandwidth faster and cheaper.” That bet may not be as safe as it seems and the explosion of streaming video and mobile technologies in recent years is beginning to cause problems. The Internet was built to transmit content such as s and web pages. In contrast, media items such as high-definition movies are magnitudes greater in size Copyright John Wiley & Sons Canada

THE NETWORK NEUTRALITY WARS
Solution One possible solution is net neutrality. Network neutrality is the concept that ISPs must allow customers equal access to content and applications, regardless of the source or nature of the content. Copyright John Wiley & Sons Canada

The Results Most analysts expect that the heaviest data consumers eventually will have to pay more, most likely in the form of tiered pricing plans. North Americans, however, have never experienced limits on the amount of data they upload and download. Nevertheless, wireless networks have already moved in the direction of these plans. Copyright John Wiley & Sons Canada

Discussion Why are telecommunications and cable companies are not in favour of net neutrality? Why are ISP’s in favour of net neutrality? Copyright John Wiley & Sons Canada

4.1 WHAT IS A COMPUTER NETWORK?
Fundamental points about network computing: They constantly exchange data with one another. The exchange of data provide companies with a number of very significant advantages. This exchange can take place over any distance & over networks of any size. A computer network is a system that connects computers and other devices via communications media so that data and information can be transmitted among them. Copyright John Wiley & Sons Canada

WHAT IS A COMPUTER NETWORK (CONTINUED)
Bandwidth is the transmission capacity of a network; it is stated in bits per second. Broadband refers to network transmission capacities ranging from approximately 1 million bits per second (megabits/s) to as much as 20 megabits/s with fibre-to-the-home. Copyright John Wiley & Sons Canada

SIZE OF COMPUTER NETWORKS
There are various types of computer networks, ranging 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 Internet PANs are short-range networks—typically a few metres—used for communication among devices close to one person. PANs can be wired or wireless. MANs are relatively large computer networks that cover a metropolitan area. MANs fall between LANs and WANs in size. WANs typically cover large geographic areas and can span the entire planet. Copyright John Wiley & Sons Canada

LOCAL AREA NETWORKS A local area network (LAN) connects two or more devices in a limited geographical region, usually within the same building, so that every device on the network can communicate with every other device. Most LANs today use Ethernet. This slide illustrates an Ethernet LAN that consists of four computers, a server, and a printer, all of which connect via a shared cable. Copyright John Wiley & Sons Canada

WIDE AREA NETWORKS Wide area networks (WANs) are networks that cover large geographic areas. WANs typically connect multiple LANs. WANs have large capacity, and they typically combine multiple channels (for example, fibre-optic cables, microwave, and satellite). WANs also contain routers. A router is a communications processor that routes messages from a LAN to the Internet, across several connected LANs, or across a wide area network such as the Internet. Copyright John Wiley & Sons Canada

ENTERPRISE NETWORK Organizations today have multiple LANs and may have multiple WANs, which are interconnected to form an enterprise network. This slide displays a model of enterprise computing. Note that the enterprise network in the figure has a backbone network. Copyright John Wiley & Sons Canada

4.2 NETWORK FUNDAMENTALS Analog and Digital Signals Communications Media and Channels Twisted-Pair Wire Coaxial Cable Fibre-Optic Cables Copyright John Wiley & Sons Canada

ANALOG AND DIGITAL SIGNALS
Networks transmit information with two basic types of signals, analog and digital. Analog signals are continuous waves that transmit information by altering the characteristics of the waves. Example: human voice Analog signals have two parameters, amplitude and frequency. Digital signals are discrete pulses that are either on or off, representing a series of bits (0s and 1s). This quality allows digital signals to convey information in a binary form that can be interpreted by computers. Copyright John Wiley & Sons Canada

MODEMS There are three types of modems: dial-up modems cable modems DSL modems The function of modems is to convert digital signals to analog signals—a process called modulation—and analog signals to digital signals—a process called demodulation. Modems are used in pairs. The modem at the sending end converts a computer’s digital information to analog signals for transmission over analog lines, such as telephone lines. At the receiving end, another modem converts the analog signal back to digital signals for the receiving computer. Copyright John Wiley & Sons Canada

COMMUNICATIONS MEDIA AND CHANNELS
Twisted-pair wire Coaxial cable Fibre optics Communicating data from one location to another requires some form of pathway or medium. These pathways, called communications channels, are composed of two types of media: cable (twisted-pair wire, cable, and fibre-optic cable) and broadcast (microwave, satellite, radio, and infrared). Cable modems are modems that operate over coaxial cable; for example, those used for cable TV. Twisted-pair wire is the prevalent form of communications wiring; it is used for almost all business telephone wiring. Fibre-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. Copyright John Wiley & Sons Canada

TRANSMISSION TECHNOLOGIES
Digital subscriber line (DSL) Asynchronous transfer mode (ATM) Synchronous optical network (SONET) T-carrier system Network Protocols Ethernet Transmission Control Protocol/Internet Protocol (TCP/IP) Digital Subscriber Line: provide high-speed transmission of digital data from homes and businesses over existing telephone lines. Asynchronous Transfer Mode: networks allow users to access almost unlimited bandwidth on demand. In addition, ATM provides support for data, video, and voice transmissions on a single communications line. Synchronous Optical Network: is an interface standard designed to carry large volumes of traffic over relatively long distances using fibre-optic lines. SONET defines optical line rates, known as optical carrier (OC) signals. T-Carrier System: is a digital transmission system that defines circuits that operate at different rates, all of which are multiples of the basic 64 Kbps used to transport a single voice call. A protocol is the set of rules and procedures governing transmission across a network. Ethernet is a common LAN protocol. Transmission Control 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). Copyright John Wiley & Sons Canada

THE FOUR LAYERS OF THE TCP/IP PROTOCOL
The Internet protocol (IP) is responsible for disassembling, delivering, and reassembling the data during transmission, a process you will see next. Before data are transmitted over the Internet, they are broken down into small, fixed bundles of data called packets. The transmission technology that breaks up blocks of data 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 receiver’s IP address, the number of packets in this message, and the number of this 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. Copyright John Wiley & Sons Canada

PACKET SWITCHING This slide illustrates a message being sent from Toronto to Calgary over a packet-switching network. Note that the different coloured packets travel by different routes to reach their destination in Calgary, where they are reassembled into the complete message. Copyright John Wiley & Sons Canada

TYPES OF NETWORK PROCESSING
Client/server computing Peer-to-peer processing Distributed processing divides processing work among two or more computers. Client/server computing links two or more computers in an arrangement in which some machines, called servers, provide computing services for user PCs, called clients. Peer-to-peer (P2P) processing is a type of client/server distributed processing where each computer acts as both a client and a server. Each computer can access (as assigned for security or integrity purposes) all files on all other computers. There are three basic types of peer-to-peer processing. 1. The first accesses unused CPU power among networked computers. 2. The second form of peer-to-peer is real-time, person-to-person collaboration. 3. The third peer-to-peer category is advanced search and file sharing. Copyright John Wiley & Sons Canada

4.3 THE INTERNET AND THE WORLD WIDE WEB
Accessing the Internet Connecting via an On-line Service (ISP) Connecting via Other Means (smart phones, ipads) The Internet (“the Net”) is a global WAN that connects approximately 1 million organizational computer networks in more than 200 countries on all continents, including Antarctica, and plays a role in the daily routine of almost 2 billion people. An intranet is a network that uses Internet protocols so that users can take advantage of familiar applications and work habits. Intranets support discovery (easy and inexpensive browsing and search), communication, and collaboration inside an organization. An extranet connects parts of the intranets of different organizations Internet service provider (ISP) is a company that offers Internet connections for a fee. Copyright John Wiley & Sons Canada

ACCESSING THE INTERNET
Each computer on the Internet has an assigned address, called the Internet protocol (IP) address. IP addresses must be unique Because the numeric IP addresses are difficult to remember, most computers have names as well. ICANN, the Internet Corporation for Assigned Names and Numbers accredits certain companies called registrars to register these names, which are derived from a system called the domain name system (DNS). Copyright John Wiley & Sons Canada

ADDRESSES ON THE INTERNET
Domain names Top-level domain Name of the organization Name of the specific computer Domain names consist of multiple parts, separated by dots, which are red from right to left. Top-level domain: the rightmost part of an Internet name; common top-level domains are .com, .edu, .gov, .mil, .org Name of the company: the next section of the Internet name Name of the specific computer: the next section of the Internet name Copyright John Wiley & Sons Canada

ADDRESSES ON THE INTERNET
IPv6 IPv4 32 bits 128 bits Currently, there are two IP addressing schemes. The first scheme, IPv4, is the most widely used. IP addresses using IPv4 consist of 32 bits, meaning that there are 232 possibilities for IP addresses, or 4,294,967,295 distinct addresses. IP addresses using IPv6 consist of 128 bits, meaning that there are 2128 possibilities for distinct IP addresses, which is an unimaginably large number. IPv6, which is replacing IPv4, will accommodate the rapidly increasing number of devices that need IP addresses, such as smart phones. Copyright John Wiley & Sons Canada

THE FUTURE OF THE INTERNET
Many experts are now concerned that Internet users will experience brownouts (temporary unavailability or slower speeds) due to three factors: the increasing number of people who work on-line, the soaring popularity of websites such as YouTube that require large amounts of bandwidth, and the tremendous demand for high-definition television delivered over the Internet. In Canada, ( is a not-for-proﬁt organization supported by the government and the private sector with the goal of doing research and implementing advanced communication networks. Copyright John Wiley & Sons Canada

THE WORLD WIDE WEB The World Wide Web Not the same thing as the Internet Home page Website Uniform resource locator Browser World wide web: A system of universally accepted standards for storing, retrieving, formatting, and displaying information via a client/server architecture. Home page: a text and graphical screen display that usually welcomes the user and explains the organization that has established the page. Website: All of the pages of a particular company or individual. Uniform resource locator: the set of letters that points to the address of a specific resource on the Web. Browser: software applications allowing Users to access the Web Copyright John Wiley & Sons Canada

BROWSER COMPETITION Companies are investing increasing amounts of resources in their browsers (Safari, Google Chrome, Mozilla Firefox, Opera , Microsoft Internet Explorer). A couple of developments are behind this trend. The first is Google, whose big plans for its Chrome browser forced Microsoft to pay more attention to its own browser, Internet Explorer (IE). The second factor was a decision by the European Union (EU). Starting in March 2010, the EU required computer manufacturers to offer European customers more freedom to choose their software. Regardless of which browser users select they should take into consideration issues of security and privacy. Copyright John Wiley & Sons Canada

4.4 INTERNET NETWORK APPLICATIONS
Discovery Communication Collaboration E-Learning and Distance Learning Virtual Universities Telecommuting Copyright John Wiley & Sons Canada

DISCOVERY Search engines Metasearch engines Publication of material in foreign languages Discovery allows users to browse and search data sources, in all topic areas, on the Web. Search engines are computer programs that search for specific information by key words and report the results. Metasearch engines search several engines at once and integrate the findings of the various search engines to answer queries posted by users. Click on the kartoo.com link to navigate the metasearch engine. Publication of material in foreign languages use an automatic translation of web pages. Some major web translation tools are Bing ( and Google ( Copyright John Wiley & Sons Canada

PORTALS Commercial (public) portals Affinity portals Mobile portals Corporate portals Industry wide portals Portal is a Web-based, personalized gateway to information and knowledge that provides relevant information from different IT systems and the Internet using advanced search and indexing techniques. Commercial (public) portals offer content for diverse communities and are most popular portals on the Internet. Affinity portals offer a single point of entry to an entire community of affiliated interests, such as a hobby group or a political party Mobile portals are accessible from mobile devices. Corporate portals offer a personalized single point of access through a Web browser Industrywide portals for entire industries. Copyright John Wiley & Sons Canada

AFFINITY PORTAL (EXAMPLE)
Example of an Affinity Portal Copyright John Wiley & Sons Canada

COMMUNICATION Electronic mail ( ) Web-based call centers (customer call center) Electronic chat room Voice Unified Electronic mail ( ) is the largest-volume application running on the Internet. Web-based call centers (customer call center) are services that provide effective personalize customer contact as an important part of Web-based customer support. Electronic chat room is a virtual meeting place where groups of regulars come to “gab”. Voice Communication With [KT]Internet telephony, also known as [KT]voice over Internet protocol or [KT]VoIP, phone calls are treated as just another kind of data. Unified Communication simplifies and integrates all forms of communications—voice, voice mail, fax, chat, , instant messaging, short message service, presence (location) services, and video conferencing—on a common hardware and software platform. Copyright John Wiley & Sons Canada

VOICE COMMUNICATION Two examples of Internet telephony (VoIP) Skype Vongae Internet telephony (VoIP) (voice-over IP) digitizes your analog voice signals, sections them into packets, and sends them over the Internet. This slide shows two examples of Voice over IP companies. Copyright John Wiley & Sons Canada

COLLABORATION Work group Work Flow Virtual group (team) Collaboration refers to efforts of two or more entities (individuals, teams, groups, or organizations) who work together to accomplish certain tasks. Work group refers specifically to two or more individuals who act together to perform some task. Workflow is the movement of information as it flows through the sequence of steps that make up an organization’s work procedures. Virtual group (team) is when group members are in different locations. Copyright John Wiley & Sons Canada

COLLABORATION (CONTINUED)
Virtual collaboration Collaboration software Electronic Teleconferencing E-Learning and Distance Learning Virtual collaboration is the use of digital technologies that enable organizations or individuals to collaboratively plan, design, develop, manage and research products, services and innovative applications. Workflow technologies facilitate the movement of information as it flows through the sequence of steps that make up an organization’s work procedures. Includes workflow management and workflow systems. Groupware refers to software products that support groups of people who share a common task or goal and who collaborate to accomplish it. Teleconferencing is the use of electronic communication that allows two or more people at different locations to hold a simultaneous conference. Videoconference is when participants in one location can see participants at other locations and share data, voice, pictures, graphics and animation by electronic means. Web conferencing is videoconferencing conducted over the Internet. Real-time collaboration tools support synchronous communication of graphical and text-based information i.e. computer-based whiteboards. Copyright John Wiley & Sons Canada

CROWDSOURCING Crowdsourcing refers to outsourcing a task to an undefined, generally large group of people in the form of an open call. Crowdsourcing refers to outsourcing a task to an undefined, generally large group of people in the form of an open call. Copyright John Wiley & Sons Canada

SOFTWARE PRODUCTS SUPPORTING COLLABORATION
Google Docs ( is a free, web-based word processor, spreadsheet, and presentation application. Microsoft’s SharePoint product ( provides shared content with version control. IBM’s Lotus Quickr ( product provides shared content with version control in the form of document directories with check-in and check-out features based on user privileges. Jive’s ( uses web collaboration and communication tools such as forums, wikis, and blogs to allow people to share content with version management, via discussion rooms, calendars, and to-do lists. Click on the links to each website. Copyright John Wiley & Sons Canada

ELECTRONIC TELECONFERENCING
The latest version of teleconferencing, telepresence systems, enable participants to seamlessly share data, voice, images, graphics, video, and animation electronically. See video on Cisco Magic The latest version of teleconferencing, telepresence systems, enable participants to seamlessly share data, voice, images, graphics, video, and animation electronically. Copyright John Wiley & Sons Canada

E-LEARNING AND DISTANCE LEARNING
E-Learning refers to learning supported by the Web. Distance learning (DL) refers to any learning situation in which teachers and students do not meet face-to-face. E-Learning refers to learning supported by the Web. Distance learning (DL) refers to any learning situation in which teachers and students do not meet face-to-face. Copyright John Wiley & Sons Canada

BENEFITS OF E-LEARNING
Online materials deliver high-quality, current content. Students have the flexibility of learning from any place at any time at their own pace. Learning time generally is shorter, and more people can be trained due to faster training time. Training costs can be reduced. Copyright John Wiley & Sons Canada

DRAWBACKS OF E-LEARNING
The purchase of additional multimedia equipment may be necessary. Students must be computer literate and may miss the face-to-face interaction with instructors. There are issues with assessing students’ work, as instructors really do not know who completed assignments. Copyright John Wiley & Sons Canada

VIRTUAL UNIVERSITIES Virtual universities are on-line universities in which students take classes from home or at an off-site location, via the Internet. A large number of existing universities offer on-line education of some form. Other universities offer limited on-line courses and degrees but use innovative teaching methods and multimedia support in the traditional classroom. Copyright John Wiley & Sons Canada

TELECOMMUTING Knowledge workers are being called the distributed workforce, or digital nomads. This group of highly prized workers is now able to work anywhere and anytime, a process called telecommuting. Knowledge workers are being called the distributed workforce, or digital nomads. This group of highly prized workers is now able to work anywhere and anytime, a process called telecommuting. Copyright John Wiley & Sons Canada

TELECOMMUTING BENEFITS
For Employees Reduced stress, improved family life Employment opportunities for single parents and persons with disabilities For Employers Increased productivity Ability to retain skilled employees Copyright John Wiley & Sons Canada

TELECOMMUTING DISADVANTAGES
For Employees Feelings of isolation Possible loss of fringe benefits Lack of socialization Lower pay (in some cases) Potential for slower promotions For Employers Difficulties in supervising work Potential information security problems Additional training costs Copyright John Wiley & Sons Canada

CHAPTER CLOSING A computer network is a system that connects computers via communications media so that data and information can be transmitted among them. There are three types of wireline communications media: twisted-pair, coaxial and fibre-optic cables The Internet is a global network of computer networks, using a common communications protocol, TCP/IP. The World Wide Web is a system that stores, retrieves, formats, and displays information accessible through a browser. There are six major categories of network applications: Discovery, Networks, E-learning, Collaboration, Virtual universities and Telecommuting Copyright John Wiley & Sons Canada

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