OSIviitemalli

The OSI model, or Open Systems Interconnection model, is a conceptual framework used to standardize the functions of a telecommunication or computing system in terms of abstraction layers. It divides communication into seven layers, each performing a specific function. These layers are, from top to bottom: Application, Presentation, Session, Transport, Network, Data Link, and Physical. The model is not a strict specification but rather a guideline for understanding and designing network protocols and architectures.

The Application layer provides network services directly to end-user applications. The Presentation layer handles data formatting, encryption, and compression. The Session layer establishes, manages, and terminates connections between applications. The Transport layer ensures reliable and transparent data transfer between end systems, often using protocols like TCP and UDP. The Network layer handles logical addressing and routing of data packets across different networks. The Data Link layer provides for reliable data transfer across a physical link, managing physical addressing and error detection. Finally, the Physical layer defines the electrical and physical specifications for devices, including the transmission and reception of raw bit streams over a physical medium.

By layering these functions, the OSI model allows for greater modularity and interoperability. Developers can focus on specific layers without needing to understand the complexities of all other layers. This abstraction promotes innovation and simplifies the design and troubleshooting of complex networks. While the TCP/IP model is more widely implemented in practice, the OSI model remains a valuable educational tool for understanding network communication.