Standards, Protocols & Layers

• Protocol


  A set of rules that allows two devices to communicate
• Common protocols


  • TCP/IP
  • HTTP
  • HTTPS
  • FTP
  • POP
  • SMTP
  • IMAP
• TCP (Transmission Control Protocol)


  Provides an error free transmission between two routers
• IP (Internet Protocol)


  Routes packets across a wide area network
• TCP/IP protocol stack


  TCP and IP together make up the foundation of communication over the Internet
• HTTP (Hypertext Transfer Protocol)


  A client-server method of requesting and delivering HTML web pages
• HTTPS (Hypertext Transfer Protocol Secure)


  Encryption and authentication for requesting and delivering HTML web pages, used when sensitive information needs to be transferred
• FTP (File Transfer Protocol)


  Used for sending files between computers, usually on a wide area network
• POP (Post Office Protocol)


  Retrieves emails from a mail server, removes it from the server and transfers to your device
• SMTP (Simple Mail Transfer Protocol)


  Sends email to an email server
• IMAP (Internet Message Access Protocol)

  Used by mail clients to manage remote mail boxes and retrieve email from a mail server
• Layers


  Dividing the complex task of networking into smaller, simpler tasks that work with each other
• Different applications for different tasks

  • web pages
  • email
  • file transfer
• Concepts related to networking

  • Encryption
  • Security
  • Authentication of users and data
  • Connection to remote servers
  • Maintaining open connections
  • Peer to peer
  • Client server models
  • Splitting data transfer into smaller packets and frames
  • Sequencing packets on arrival
  • Sending packets between routers on a WAN
  • Sending frames between devices on a LAN
  • Error checking packets and frames on arrival
  • Requesting data to be resent if necessary
  • Using different cables: fibre optic, twister pair, coaxial
  • Using wireless with frequencies and channels
  • Simplex and duplex transmissions
  • The complexity of networking
• Layering


  Dividing the complex task of networking into smaller, simpler tasks that work with each other
• Layers


  • Hardware and/or software for each layer has a defined responsibility
  • Each layer provides a service to the layer above it
• Advantages of layering


  • Reduces the complexity of the problem into manageable sub-problems
  • Devices can be manufactured to operate at a particular layer
  • Products from different vendors will work together
• Layers of the TCP/IP protocol stack

  • Application
  • Transport
  • Network
  • Link
• All incoming and outgoing data packets pass up and down through the various layers when you communicate on a network
• TCP/IP protocol and use of layers

  1. Application layer uses appropriate protocol

  2. Transport layer uses TCP to establish end-to-end connection and split data into packets

  3. Network layer uses IP to add source and destination IP addresses

  4. Link layer adds source and destination MAC addresses
• Application layer protocols


  • HTTP
  • HTTPS
  • FTP
• The MAC address is changed at each hop on the route