CSC 134 CHAPTER7 PART 1

• Communication systems


  Electronic systems that transmit data from one location to another
• Basic elements of communication systems

  • Sending and receiving devices
  • Connection devices
  • Data transmission specifications
  • Communication channel
• Sending and receiving devices


  • Initiate an instruction to transmit/accept data, instruction, or information
  • Originate (send) as well as accept (receive) messages in the form of data, information, and/or instructions
• Examples of sending and receiving devices

  • Mainframe computers
  • Servers
  • Desktop computers
  • Notebook computers
  • Smartphones
  • Portable media players
  • Handheld game consoles
  • GPS receivers
• Physical connection types

  • Twisted pair cable
  • Telephone lines
  • Ethernet cables
  • Coaxial cable
  • Fiber-optic cable
• Wireless connection types

  • Radio waves
• Modem


  Modulator-demodulator<|>Modulation is the process of converting from digital to analog<|>Demodulation is the process of converting from analog to digital
• Transfer rate


  Speed in which modems transfer data, usually measured in megabits per second (Mbps)
• Types of modems

  • Digital subscriber line (DSL)
  • Cable
  • Wireless (WWAN)
• Types of signals

  • Analog
  • Digital
• Transfer rate units

  • Mbps (million bits per second)
  • Gbps (billion bits per second)
  • Tbps (trillion bits per second)
• Connection services for corporations

  • Leased lines (T1, T3, DS3)
  • Optical carrier lines (OC)
• Connection services for individuals

  • Digital subscriber line (DSL)
  • Cable
  • Satellite
  • Cellular (3G, 4G)
  • Fiber Optic Service (FiOS)
• Bandwidth


  How much information can move across the communication channel in a given amount of time
• Categories of bandwidth

  • Voiceband (or low bandwidth) - standard telephone
  • Medium band - leased lines for high-speed
  • Mid-range computer and mainframes
  • Broadband for DSL, cable, satellite connections to the Internet
  • Baseband for individual connections for computers in close range
• Have an "always-on" connection to access e-mail, websites, cloud services, and apps
• Protocols


  Communication rules for exchanging data between computers
• Examples of protocols

  • HTTPS - Hypertext Transfer Protocol Secure
  • TCP/IP - Transmission control protocol/Internet protocol
• DNS

  Domain name service that resolves IP addresses to names
• Packetization


  Information broken down into small parts (packets) and then reassembled
• Network


  A communication system that connects two or more computers so they can exchange information and share resources
• Advantages of networks

  • Specialized Terms in a Network
  • Network Types
  • Network Architecture
• Network topologies


  • Bus
  • Ring
  • Star
  • Tree
  • Mesh
• Network strategies

  • Client/Server
  • Peer-to-Peer (P2P)
• Client/Server network


  Central computers coordinate and supply services to other nodes on the network
• Peer-to-Peer (P2P) network

  All nodes have equal authority and can act as both client and server
• Network devices

  • Modem
  • Router
  • Network Interface Card
  • Hub or Switch
• Intranet


  Private network within an organization that works like the Internet
• Extranet


  Private network that connects more than one organization and works like the Internet, but provides suppliers and other trusted partners with limited access
• Network security technologies


  • Firewall
  • Proxy server
  • Intrusion detection system (IDS)
  • Virtual private network (VPN)
• Telepresence seeks to create the illusion that you are actually at a remote location