• TCP (Transmission Control Protocol)
  • IP (Internet Protocol)
  • TCP/IP suite is used by OSes for communication on a network
  • TCP rests on top of the IP foundation

Core Protocols

  • Full suite of protocols including:
  • Add header to data inherited from the layer above
    • Layers add own data and addresses
    • Layer 7, 6, 5
      • Data and instructions are generated by apps running on source host
      • Known as payload
    • Layer 4
      • Transport layer protocol adds header to payload
      • Usually TCP or UDP
      • Includes port number to identify receiving app
    • Layer 3
    • Layer 2
      • Packet passed to data link layer on NIC
      • Encapsulates data with its own header and trailer --> frame
    • Layer 1
      • Physical layer on NIC receives frame and places transmission on the network
  • Receiving host de-encapsulates message at each layer and presents payload to receiving apps
    • Reverse order
    • In transit, transmissions might pass through number of connectivity devices
  • Connectivity devices
    • Devices allowing two or more networks/parts of one network to connect and exchange data
    • Known by highest OSI they read and process
    • Connectivity devices

Networking Computer Science