Chapter 4 Telecommunications, the Internet, Intranets, and Extranets

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Chapter 4Telecommunications, the Internet,
Intranets, and Extranets
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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

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Telecommunications System Components
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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)

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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 computers digital signals into analog
  and vice versa

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Communications Media
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Telecommunications Hardware
Table 4.3 Common Telecommunications Devices
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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

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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

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Network Types

• Personal area network (PAN)
• Local area network (LAN)
• Metropolitan area network (MAN)
• Wide area network (WAN)
• International networks
• Mesh networking

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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

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Client/Server Systems

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

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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
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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

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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

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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

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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

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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

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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

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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 Computers Safari

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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

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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

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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

• Extranet
• A network based on Web technologies that links
  selected resources of a companys 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

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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