7 Application layer 6 Presentation layer 5 Session layer 4 Transport layer 3 Network layer 2 Data link layer 1 Physical layer
Application layer: equivalent to the interface provided to the application, it is the communication service for the application.
Presentation layer: The main function of this layer is to define data format and encryption.
Session layer: It defines how to start, control and end a session.
Transport layer: The function of this layer is to select which transport protocol to use and add protocol headers. TCP, UDP, SPX
Network layer: establishes logical links for data transmission between point-to-point. And forward packets in groups.
Data Link Layer: Frames data and handles flow control. This layer specifies the topology and provides hardware addressing.