Fundamentals of Information Systems
Fourth Edition
Chapter 4
Telecommunications, the Internet,
Intranets, and Extranets
An Overview of Telecommunications
• Telecommunications: the electronic transmission of signals for communications
• Telecommunications medium: anything that
carries an electronic signal and interfaces between a sending device and a receiving device
An Overview of Telecommunications (continued)
Figure 4.1: Elements of a Telecommunications System
Channel Bandwidth
• Telecommunications professionals consider the capacity of the communications path or channel when they recommend transmission media for a business
• Channel bandwidth: the rate at which data is exchanged over a communication channel
– Usually measured in bits per second (bps)
Communications Media
Table 4.1: Guided Transmission Media Types
Communications Media (continued)
Table 4.2: Wireless Technologies
Communications Media (continued)
Communications Media (continued)
broadband over power lines
Radio
Networks and Distributed Processing
• Computer network: the communications media, devices, and software needed to connect two or more computer systems and/or devices
• Network nodes: the computers and devices on the networks
Network Types
• Personal area network (PAN)
• Local area network (LAN)
• Metropolitan area network (MAN)
• Wide area network (WAN)
• International networks
• Mesh networking
Network Types (continued)
Figure 4.4: A Typical LAN
Network Types (continued)
Figure 4.5: A Wide Area Network
Communications Software and Protocols
• Communications protocol: a set of rules that govern the exchange of information over a
communications channel
• Protocols govern several levels of a telecommunications network, such as:
– Hardware device level – Application program level
Wireless Communications Protocols
• Wireless communications protocols are still evolving as the industry matures
• The Institute for Electrical and Electronic Engineers (IEEE) has been instrumental in defining numerous telecommunications standards
Use and Functioning of the Internet
• Internet: a collection of interconnected networks, all freely exchanging information
• ARPANET
– The ancestor of the Internet
– A project started by the U.S. Department of Defense (DoD) in 1969
• Internet Protocol (IP): communication standard that enables traffic to be routed from one network to another as needed
How the Internet Works
• The Internet transmits data from one computer (called a host) to another
• If the receiving computer is on a network to which the first computer is directly connected, it can send the message directly
• If the receiving computer is not on a network to which the sending computer is connected, the
sending computer relays the message to another computer that can forward it
How the Internet Works (continued)
• Data is passed in chunks called packets
• Transmission Control Protocol (TCP): widely used transport-layer protocol that is used in
combination with IP by most Internet applications
• Uniform Resource Locator (URL): an assigned address on the Internet for each computer
How the Internet Works (continued)
Figure 4.11: Routing Messages over the Internet
How the Internet Works (continued)
Figure 4.12: Several Ways to Access the Internet
Internet Service Providers
• Internet service provider (ISP): any company that provides individuals or organizations with access to the Internet
• Most charge a monthly fee
• Many ISPs and online services offer broadband Internet access through digital subscriber lines (DSLs), cable, or satellite transmission
The World Wide Web
• The Web, WWW, or W3
• A menu-based system that uses the client/server model
• Organizes Internet resources throughout the world into a series of menu pages, or screens, that
appear on your computer
• Hypermedia: tools that connect the data on Web pages, allowing users to access topics in whatever order they want
The World Wide Web (continued)
Figure 4.13: Sample Hypertext Markup Language
Web Browsers
• Web browser: software that creates a unique, hypermedia-based menu on a computer screen, providing a graphical interface to the Web
• The menu consists of graphics, titles, and text with hypertext links
• Popular Web browsers: Microsoft Internet Explorer, Netscape Navigator, Mozilla Firefox, Apple
Computer’s Safari
Search Engines and Web Research
• Search engine: Web search tool
– Examples: Yahoo.com, Google.com
• Most search engines are free
• Searches can use words, such as AND and OR to refine the search
• Meta-search engine: submits keywords to several individual search engines and returns results from all these search engines
Search Engines and Web Research (continued)
Table 4.10 Popular Search Engines
Internet and Web Applications: E-Mail, Instant Messaging, and Push
Technology
• E-mail is no longer limited to simple text messages
– Sound and images can be embedded in messages – Files that contain text documents, spreadsheets,
graphs, or executable programs can be attached
• Instant messaging: allows two or more individuals to communicate online using the Internet
Career Information and Job Searching
• Internet is an excellent source of job-related information
• Most medium and large companies have Internet sites that list open positions, salaries, benefits, and people to contact for further information
• Some sites can help you develop a good résumé and an effective cover letter, apply for jobs online, prepare for a job interview, and negotiate a good employment contract
Web Log (Blog), Video Log (Vlog), and Podcasting
• Web log (blog): Web site that people can create and use to write about their observations,
experiences, and feelings on a wide range of topics
• Video log (vlog): video content placed on the
Internet using the same overall approach as a blog
• Podcast: audio blog, like a personal radio station on the Internet
– Extends blogging by adding audio messages
Chat Rooms
• Chat room: facility that enables two or more people to engage in interactive “conversations”
over the Internet
Internet Phone and Videoconferencing Services
• Internet phone service enables you to
communicate with others around the world
– Relatively inexpensive
– Useful for international calls
– Ability to keep your phone number when you move to another location
• Internet videoconferencing
– Supports both voice and visual communications
Shopping on the Web
• Shopping on the Web for books, clothes, cars, medications, and even medical advice can be convenient, easy, and cost effective
• Bot: software tool that searches the Web for information, products, or prices
Music, Radio, Video, and TV on the Internet
• Music, radio, and video are hot growth areas on the Internet
• Audio and video programs can be played on the Internet, or files can be downloaded for later use
Intranets and Extranets
• Intranet
– Internal corporate network built using Internet and World Wide Web standards and products
– Used by employees to gain access to corporate information
– Reduces need for paper
Intranets and Extranets (continued)
• Extranet
– A network based on Web technologies that links selected resources of a company’s intranet with its customers, suppliers, or other business partners
• Virtual private network (VPN): secure connection between two points across the Internet
• Tunneling: process by which VPNs transfer
information by encapsulating traffic in IP packets over the Internet
Net Issues
• Management issues
– No centralized governing body controls the Internet
• Service and speed issues
– Web server computers can be overwhelmed by the amount of “hits” (requests for pages)
• Privacy, fraud, security, and unauthorized Internet sites
Summary
• Telecommunications: electronic transmission of signals for communications
• Computer network: communications media,
devices, and software needed to connect two or more computer systems or devices
• Network types: personal area network (PAN), local area network (LAN), metropolitan area network
(MAN), wide area network (WAN), and international networks
Summary (continued)
• Internet: collection of interconnected networks, all freely exchanging information
• Internet Protocol (IP): communication standard that enables traffic to be routed from one network to
another as needed
• Uniform Resource Locator (URL): an assigned address on the Internet for each computer
Summary (continued)
• Intranet: internal corporate network built using Internet and World Wide Web standards and protocols
• Extranet: network based on Web technologies that links selected resources of a company’s intranet with its customers, suppliers, or other business partners
