7.2.12

• Protocol


  An agreed set of rules that allow two devices to communicate
• Protocols


  • Can be for wired or wireless transfer
• Protocols


  • Printer communicating with a computer
  • Phones/Speakers communicating wirelessly by Bluetooth
  • Webpages being transferred
  • Hardware devices communicating with a PC
  • Phone calls
  • Headphones
• Protocols allow easier development one 'layer' at a time
• Protocols allow multiple companies to work together
• TCP/IP (Transmission Control Protocol/ Internet Protocol)


  • Allows devices to communicate AND has error checking facilities to ensure all packets are received
  • Is able to create and direct packets to the around a network and requests replacement copies if lost
• TCP/IP uses


  • FTP
  • SMTP
  • IMAP
  • HTTP
• UDP (User Datagram Protocol)


  • Has no error recovery services
  • When streaming, it is better to accept occasional lost packets and temporary dip in quality than pausing whilst replacement packets are requested
• UDP uses


  • Online gaming
  • Streaming Media
• HTTP (Hypertext Transfer Protocol)


  • Allows the transfer of multimedia webpages over the internet
  • This is important as the HTTP protocol allows multiple different web browsers to display and format web pages as the original author intended
• FTP (File Transfer Protocol)


  • Allows the transfer of large files over a network
  • Uses TCP/IP, so has in-built error checking and re-transmission requests as necessary
• DHCP (Dynamic Host Configuration Protocol)

  • Assigns IP addresses to devices on a network
  • IP address uniquely identifies a device on a network
  • Allocated when a device connects to the network
  • Single sessions only, then reallocated
• SMTP (Simple Mail Transfer Protocol)

  Used to transfer emails between internet servers
• IMAP (Internet Message Access Protocol)

  • Is used to upload/download email between the user's computer and an internet server
  • Emails are accessible anywhere
  • Emails are stored on the server instead of devices, which saves storage space