OSI Model

  1. Handy Memorization Tip
    • Please
    • Do
    • Not
    • Throw
    • Sausage
    • Pizza
    • Away
  2. Application Layer (7)
    This layer interfaces directly with the network-aware application, giving it access to network resources.

    Without this layer, no user application would be able to get access to the network.
  3. Presentation Layer (6)
    Encodes the data being sent or recieved into a generic format that will be understood by both devices. For example, a web browser might recieve data in HTML format or a picture in JPG format, which are generic and well understood standards.
  4. Session Layer (5)
    Begins, ends, and manages the sessions between devices.
  5. Transport Layer (4)
    Handles the reliablity of the connection and logical separation of applications. For example, if a computer is surfing the internet with a web browser and at the same time listening to internet-radio, this layer ensures the correct data arrives to the correct application.

    In addition, this layer handles flow-control (ensuring one side does not send information faster than the other can receive) and data integrity (ensuring the data is not corrupt).

    The most common Transport layer protocol is TCP.
  6. Network Layer (3)
    Provides logical addressing services allowing a device to dictate the source and destination address used for end-to-end communication.

    This layer is also responsible for routing the packet from its source to its destination.

    The most common Network layer protocol is IP.
  7. Data Link Layer (2)
    Provides physical addressing services allowing a device to dictate the source and destination address used for local network communication.

    This layer permits communication between devices connected to the same network.

    This layer is also responsible for error detection.
  8. Physical Layer (1)
    Defines the physical standards used for network communication.
  9. Application Layer (7)
    • User Interface
    • Communication partner identification
  10. Presentation Layer (6)
    • Data format (file format)
    • Encrytion, translation, and compression
    • Data format and exchange
  11. Session Layer (5)
    • Keeps data streams separate (session identification)
    • Set up, maintain and tear down communication sessions
  12. Transport Layer (4)
    • Reliable (connection-oriented) and unreliable (connectionless) communications
    • End-to-End flow control
    • Port and socket numbers
    • Segmantation, sequecing, and combination
  13. Network Layer (3)
    • Logical addresses
    • Path determination (identification and selection)
    • Routing packets
  14. Data Link Layer (2)
    Logical Link Control (LLC)
    Media Access Control (MAC)
    • Convert bitsinto bytes and bytes into frames
    • MAC address, aka burned in address (BIA), hardware address
    • Logical network topology
    • Media access
    • Flow control-Acknowledgement, buffering, windowing
    • Parity and CRC
  15. Physical Layer (1)
    • Move bits across media
    • Cables, connectors, pin positions
    • Electrical signals (voltage, bit synchronization)
    • Physical topology (network layout)
Card Set
OSI Model
Using the OSI Model