1. Chapter 4 Telecommunications, the Internet, Intranets, and Extranets

2. 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

3. Telecommunications System Components

4. 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)

5. Types of Signals Analog signal Continuous waveform
Passes through communications medium
Used for voice communications
Digital signal
Discrete waveform -- Transmits data coded into two discrete states as 1-bits and 0-bits
Used for data communications
Modem
Translates computer’s digital signals into analog and vice versa

6. Communications Media

7. Telecommunications Hardware
Table 4.3: Common Telecommunications Devices

8. Services
Digital subscriber line (DSL): telecommunications service that delivers high-speed Internet access to homes and small businesses over the existing phone lines of the local telephone network
All major long distance carriers offer wireless telecommunications services that enable you to place phone calls or access the Internet

9. 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

10. Network Types Personal area network (PAN) Local area network (LAN)
Metropolitan area network (MAN)
Wide area network (WAN)
International networks
Mesh networking

11. Distributed Processing
Centralized processing: all processing occurs in a single location or facility
Decentralized processing: processing devices are placed at various remote locations
Distributed processing: computers are placed at remote locations but connected to each other via a network

12. Client/Server Systems
Client/Server system: multiple computer platforms are dedicated to special functions, such as database management, printing, communications, and program execution

13. 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 are still
evolving as the industry matures

14. Communications Software
Network operating system (NOS): systems software that controls the computer systems and devices on a network and allows them to communicate with each other
Network-management software: software that a manager uses on a networked desktop
Monitors the use of individual computers and shared hardware (such as printers)
Scans for viruses
Ensures compliance with software licenses

15. 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

16. 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
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

17. How the Internet Works Accessing the Internet Connect via LAN server
Connect via Serial Line Internet Protocol (SLIP)/Point-to-Point Protocol (PPP)
Connect via an online service
Several other ways to connect
Example: WAP

18. 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

19. 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
Hypertext Markup Language (HTML): the standard page description language for Web pages
HTML tags: codes that let the Web browser know how to format text - as a heading, as a list, or as body text - and whether images, sound, and other elements should be inserted

20. 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

21. 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

22. Internet Cell Phones and Handheld Computers
Some cell phones can be connected to the Internet to:
Search for information
Buy products
Chat with business associates and friends
Handheld computers and other devices can be connected to the Internet using phone lines or wireless connections, such as Wi-Fi

23. Intranets and Extranets
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
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

24. Net Issues Management issues Service and speed 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