layers

• HTTP


  • hyper text transfer protocol
  • defines rules followed by web browser + server when requesting + supplying info
• HTTPS


  • hyper text transport protocol secure
  • uses SSL to encrypt communications between a web browser + sever to ensure they are secure
• FTP


  • file transfer protocol
  • defines rules for transferring files between computers
• POP


  • post office protocol
  • used by client to retrieve emails from mail server
  • emails downloaded then deleted from server
• IMAP


  • internet message access protocol
  • allows multiple devices access to mail on a server
  • messages can be read, organised and flagged
• SMTP


  • simple mail transfer protocol
  • defines rules for sending emails from client to server and between servers
• TCP


  • transmission control protocol
  • splits data from applications into smaller packets that can be sent across a network
• IP


  • internet protocol
  • adds a header to each packet
  • includes source + destination IP address
• what is a layer?

  • protocols assigned to them
  • each has a specific function to enable communication to take place
• application layer

  • allows communication between clients + server
  • HTTP(S); FTP; POP; IMAP; STP
• transport layer


  • splits data into packets
  • TCP
• internet layer


  • adds IP address of sender and recipient
  • IP
• links layer


  • adds MAC address
  • converts data to electrical signals
  • ethernet; Wi-Fi
• advantages of layers


  • one layer can be developed without affecting others
  • enables software + hardware manufacturers to develop compatible products
  • easier to identify and correct networking errors
• how is data sent across a network?

  • passes through each layer in turn; encapsulated with more information
  • when packet is received, each layer is read + decoded in reverse layer