What is the OSI (Open Systems Interconnection) model? [2023]

The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into distinct layers. It was developed by the International Organization for Standardization (ISO) to facilitate interoperability and communication between different systems and network devices. The OSI model consists of seven layers, each responsible for specific tasks related to data communication and processing. These layers work together to enable data exchange between devices on a network.

The seven layers of the OSI model, from the top layer to the bottom layer, are:

Application Layer (Layer 7): This is the top layer and represents the interface between the user or application and the underlying network services. It provides network services directly to end-users, such as email, file transfer, and remote access.

Presentation Layer (Layer 6): The presentation layer is responsible for data translation, encryption, and compression, ensuring that data from the application layer is in a suitable format for transmission and vice versa.

Session Layer (Layer 5): The session layer establishes, maintains, and terminates connections between devices. It manages sessions, allowing for synchronized and orderly communication between applications.

Transport Layer (Layer 4): The transport layer handles end-to-end communication and ensures the reliable and orderly delivery of data between source and destination devices. It also manages flow control and error detection and correction.

Network Layer (Layer 3): The network layer deals with routing and forwarding data packets across multiple networks. It determines the best path for data transmission and handles logical addressing.

Data Link Layer (Layer 2): The data link layer provides error-free transmission of data frames between directly connected devices on the same network. It handles physical addressing (MAC addresses) and error detection.

Physical Layer (Layer 1): The bottom layer deals with the physical transmission of data over the network medium, such as cables, switches, and routers. It defines the electrical, mechanical, and functional aspects of the hardware.

The OSI model serves as a reference model for networking protocols and standards, allowing different systems to communicate and interoperate effectively. It simplifies the complexity of networking by dividing the communication process into manageable layers, each responsible for a specific set of functions.