Chapter 06: Computer Networks PDF

Chapter 06: Computer Networks Stair, Reynolds and Chesney: Principles of Business Information Systems, Fourth edition (9781473774605) © Cengage Learning 2021 For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesn...

Chapter 06: Computer Networks Stair, Reynolds and Chesney: Principles of Business Information Systems, Fourth edition (9781473774605) © Cengage Learning 2021 For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Principles Effective communications are essential to organizational success Communications technology lets more people send and receive all forms of information over great distances Because the Internet and the World Wide Web are becoming more universally used and accepted for business use, management, service and speed, privacy and security issues must continually be addressed and resolved. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Learning Objectives Define the terms ‘communications’ and ‘telecommunications’ and describe the components of a telecommunications system. Identify several communications hardware devices and discuss their function Briefly describe how the Internet works, including Alternatives for connecting to it and the role of Internet service providers. Describe the World Wide Web and the way it works. Explain the use of web browsers, search engines and other web tools. Define the terms ‘intranet’ and ‘extranet’ and discuss how organizations are using them For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Computer Networks Why Learn About Computer Networks? For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunications Telecommunication: The electronic transmission of signals for communications. Telecommunications medium: Any material substance that carries an electronic signal to support communications between a sending and receiving device such as telephone, radio, and television. Telecommunications impacts businesses greatly because it lessens the barriers of time and distance For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  A general model of telecommunications A sending unit such as a person, a computer system, a terminal, or another device, sends the message signal to a telecommunications device. The telecommunications device may process the signal, such as convert it into a different form or from one type to another. The telecommunications device then sends the signal through a medium. Another telecommunications device connected to the receiving computer (6) receives the signal. The process can be reversed, and the receiving unit can send another message to the original sending unit. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning A general model of telecommunications For use with Principles For useof Business with PrinciplesInformation Systems, of Business Information 4e 3e Systems, by Stair, Reynolds by Stair, Reynolds & Chesney & Chesney © 2018 Cengage Learning © 2021 Cengage Learning  A characteristic of telecommunications An important characteristic of telecommunications is the speed at which information is transmitted, which is measured in bits per second (bps). Common speeds are in the range of thousands of bits per second (Kbps) to millions of bits per second (Mbps) and even billions of bits per second (Gbps). Channel bandwidth The rate at which data is exchanged over a communications channel, usually measured in bits per second (bps). Broadband communications A telecommunications system in which a very high rate of data exchange is possible. Narrowband communications A telecommunications system that supports a much lower rate of data exchange than broadband. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Synchronous & Asynchronous communication Communication can occur synchronously or asynchronously: With synchronous communication, the receiver gets the message almost instantaneously, when it is sent. Examples are a phone call, and instant messaging services such as MSN With asynchronous communication there is a measurable delay between the sending and receiving of the message, sometimes hours or even days. Examples are sending a letter through the post office and e-mail Both types of communications are important in business For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunication Channels » Simplex channel : transmits data in only one direction. » Half-duplex channel: transmits data in either direction but not simultaneously. » Full-duplex: channel permits data transmission in both directions at the same time. » Channel bandwidth: refers to the rate at which data is exchanged, usually measured in bits per second (bps). For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunication media types Guided transmission (using a solid medium) – Twisted-pair wire – Coaxial cable – Fiber-optic cable – Broadband over power lines For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunication media types Wireless Transmission Media Types: Microwave Transmission Microwave is a high-frequency (300 MHz–300 GHz) signal sent through the air. Microwave station receives a signal, amplifies it and retransmits it to the next microwave transmission tower. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunication media types Satellite Transmission – Communications satellites are relay stations that receive signals from one Earth station, amplifies the relatively weak signal and then rebroadcast them at a different frequency to another. – The advantage of satellite communications is that it can receive and broadcast over large geographic regions. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Transmission Media Types » 3G Wireless Communication – Wireless communication for mobile devices has evolved through four generations of technology and services. » 4G Wireless Communication – 4G broadband mobile wireless is delivering enhanced versions of multimedia, smooth video streaming, universal access, portability across all types of device and, eventually, worldwide roaming. » 5G Wireless Communication – Brings higher data transmission rates, lower power consumption, higher connection reliability with fewer dropped calls, increased geographic coverage and lower infrastructure costs. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Transmission Media Types » Wifi – Wi-fi is a medium-range wireless option typically operating up to about 30 metres around a single building. – With a wi-fi network, the user’s computer, smartphone or tablet has a – Wireless adapter that translates data into a radio signal and transmits it using an antenna » Near field communication (NFC) – NFC is a very short-range wireless connectivity technology designed for consumer electronics, smartphones and credit cards. Once two NFC-enabled devices are in close proximity (touching or a few centimeters apart), they exchange the necessary communications parameters and passwords to enable Bluetooth, wi-fi or other wireless communications between the devices. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunications Hardware » Modems: A device that converts (modulates and demodulates) communications signals so they can be transmitted over the communication media. Modulation and Demodulation:Translating data from digital to analogue is called ‘modulation’, and translating data from analogue to digital is called ‘demodulation’. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning How a Modem Works For use with Principles For useof Business with PrinciplesInformation Systems, of Business Information 4e 3e Systems, by Stair, Reynolds by Stair, Reynolds & Chesney & Chesney © 2018 Cengage Learning © 2021 Cengage Learning  Telecommunications hardware » Private Branch Exchange (PBX):is a telephone switching exchange that serves a single organization. It enables users to share a certain number of outside lines (trunk lines) to make telephone calls to people outside the organization. A PBX also enables the routing of calls between individuals within the organizations. » Bridge: A bridge connects one local area network (LAN) to another LAN that uses the same telecommunications protocol. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Telecommunications hardware » Switch: A device containing ports to which all the devices on the network can connect, it uses a physical device address in each incoming message on a network to determine to which output port it should forward the message to reach another device on the same network. » Router: A telecommunications device that forwards data packets across two or more distinct computer networks. » Gateway: A telecommunications device that serves as an entrance to another network. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Networks and distributed processing A computer network consists of communications media, devices, and software needed to connect two or more computer systems or devices The computers and devices on the networks are called network nodes Nodes can share data, information, and processing jobs Organizations can use networks to share hardware, programs, and databases Networks enable geographically separated workgroups to share information, which fosters teamwork, innovative ideas, and new business strategies For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Network types Personal Area Network: supports the interconnection of information technology close to one person Local Area Network: connects computer systems and devices within a small area (e.g., an office or a home) Metropolitan Area Network: connects users and their devices in an area that spans a campus or city Wide Area Network: connects large geographic regions International networks: Networks that link systems between countries are called international networks. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning Network types For use with Principles For useof Business with PrinciplesInformation Systems, of Business Information 4e 3e Systems, by Stair, Reynolds by Stair, Reynolds & Chesney & Chesney © 2018 Cengage Learning © 2021 Cengage Learning WAN For use with Principles For useof Business with PrinciplesInformation Systems, of Business Information 4e 3e Systems, by Stair, Reynolds by Stair, Reynolds & Chesney & Chesney © 2018 Cengage Learning © 2021 Cengage Learning  Client/Server systems In client/server architecture computers called servers are dedicated to special functions Each server is accessible by all computers on the network Servers can be computers of all sizes A client is any computer (often a user’s personal computer) that sends messages requesting services from the servers on the network For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Securing Data Transmission Organizations with widespread operations need a way to maintain the security of communications with employees and business partners, wherever their facilities are located. Encryption of data is one approach taken to protect the security of communications over both wired and wireless networks Encryption is the process of converting an original message into a form that can be understood only by the intended receiver. Encryption key is a variable value that is applied (using an algorithm) to a set of unencrypted text to produce encrypted text or to decrypt encrypted text. Cipher: The cryptographic algorithm used to encrypt the plaintext. Ciphertext is the encrypted form of a message For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning Securing Data Transmission For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  The Internet The Internet is the world’s largest computer network Actually, it is a collection of interconnected networks, all freely exchanging information. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  The Web The World Wide Web was developed as an internal document-management system. The World Wide Web (web, WWW, or W3) has grown to a collection of tens of thousands of independently owned computers that work together as one in an Internet service. A Web browser is used to access and read Web pages which are usually written in HyperText Markup Language (HTML) For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Web 2.0 » Web 2.0, also called as Social Web, refers to World Wide Web websites that emphasize user- generated content, usability, participatory culture and interoperability (this means that a website can work well with other products, systems, and devices) Ref: Reference Book No. 1, Chapter 5 – Joseph Valacich , Christoph Schneider, "Information Systems Today: Managing in a Digital World" 7th Edition, 2015 ISBN-13: 978-0133940473 ISBN-10: 01339404705 For use with Principles For useof Business with PrinciplesInformation Systems, of Business Information 4e 3e Systems, by Stair, Reynolds by Stair, Reynolds & Chesney & Chesney © 2018 Cengage Learning © 2021 Cengage Learning  Web 2.0 Technologies » Wikis: a website or database developed collaboratively by a community of users, allowing any user to add and edit content. » Tags: It provide a useful way to group related posts together and to quickly tell readers what a post is about. » Blogs: A blog is a discussion or informational website published on the World Wide Web. » Netcast: A broadcast transmitted over the Internet. » Self Publishing: It is the publication of media by its author without the involvement of an established publisher. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Web 2.0 Technologies » Social Networking: the use of dedicated websites and applications to interact with other users, or to find people with similar interests to one's own. » Viral Marketing: a method of marketing whereby consumers are encouraged to share information about a company's goods or services via the Internet. » Crowdsourcing: obtain (information or input into a particular task or project) by getting the services of a large number of people, either paid or unpaid, typically via the Internet. Ref: Reference Book No. 1, Chapter 5 – Joseph Valacich , Christoph Schneider, "Information Systems Today: Managing in a Digital World" 7th Edition, 2015 ISBN-13: 978-0133940473 ISBN-10: 01339404705 For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Intranet and Extranet Intranet: an intranet is an internal company network built using Internet and World Wide Web standards and products. Extranet: When selected externals (such as supplies, customers, business partners) are given access to the intranet, it becomes an extranet. For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Summary Telecommunications: the electronic transmission of signals for communications, by such means as telephone, radio, and television Guided transmission media types: twisted-pair wire, coaxial cable, fiber-optic cable, and broadband over power lines Wireless transmission types: microwave, radio, and infrared For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Summary (cont.) Network types: personal area network (PAN), local area network (LAN), metropolitan area network (MAN), wide area network (WAN), international networks, and mesh networking Client/server systems: multiple computer platforms dedicated to special functions such as database management, printing, communications, and program execution For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning  Review Questions 1. What is the difference between synchronous and asynchronous communication? 2. Describe a metropolitan area network. How does it compare to a LAN? 3. Describe microwave transmission. 4. What can you do with a PAN? 5. What are some of the uses of NFC? 6. What is an intranet? For use with Principles of Business Information Systems, 4e by Stair, Reynolds & Chesney © 2021 Cengage Learning