What is OSI Model

The OSI (Open Systems Interconnection) model is a framework that describes how communications systems operate. It is a seven-layer model that represents how data is transmitted and processed across different networks. Each layer has a specific function and is designed to interact with the layers above and below it.

The seven layers of the OSI model are:

1. Physical Layer: This layer deals with the physical transmission of data across a network. It includes the cables, connectors, and other hardware components that are used to transmit data.
2. Data Link Layer: This layer is responsible for creating a reliable link between two devices on a network. It provides error detection and correction, and is responsible for creating a logical link between two devices.
3. Network Layer: This layer is responsible for routing data across a network. It determines the best path for data to travel and ensures that data is delivered to its intended destination.
4. Transport Layer: This layer is responsible for ensuring that data is delivered reliably and in the correct order. It provides flow control and error recovery mechanisms.
5. Session Layer: This layer is responsible for establishing, maintaining, and terminating connections between devices on a network. It also manages communication sessions between devices.
6. Presentation Layer: This layer is responsible for converting data from one format to another. It ensures that data is in a format that can be understood by the recipient device.
7. Application Layer: This layer is responsible for providing services to applications that use the network. It includes protocols that are used for specific applications, such as email and file transfer.

The OSI model is a useful tool for understanding how communications systems operate. It helps to identify the different components of a network and the roles that they play. It also helps to identify where problems may occur and to troubleshoot those problems.

The OSI model is not a real protocol, but a reference model, this means it’s a logical framework that helps to understand the different layers of a communication process, each layer has it’s own protocols and standards that must be followed for the communication to be successful and effective.

This model is used in many areas of communication like: LAN, WAN, Internet, but also in other areas like transportation, energy, and many more. Every layer of the OSI model has its own protocols, which are defined by different standardization organizations.

In summary, the OSI model is a framework that describes how communications systems operate. It is a seven-layer model that represents how data is transmitted and processed across different networks. Each layer has a specific function and is designed to interact with the layers above and below it. The OSI model is useful for understanding how networks operate and for troubleshooting problems that may occur.