The OSI (Open Systems Interconnection) model shows how applications communicate over a network. It consists of seven layers. They are:
- Application layer: Applications can access the network services in this layer.
- Presentation layer : Data encryption occurs in this layer, and it ensures that the data is in a usable format.
- Session layer: It is responsible for controlling ports and sessions.
- Transport layer : Responsible for end-to-end communication over the network. It uses TCP and UDP transmission protocols, among others.
- Network layer : It is responsible for providing routing paths for communication.
- Data Link Layer : Defines the format of data and is responsible for encoding and decoding it.
- Physical layer : It is responsible for transferring the raw data through the communication medium.
The OSI model is important in understanding and isolating the source of the problem and is generally used for troubleshooting purposes.