Protokollebenen

Protokollebenen, often translated as protocol layers, refer to the conceptual organization of communication protocols within a network. This model divides the complex process of network communication into distinct, manageable layers, each responsible for a specific set of functions. This layered approach simplifies design, implementation, and troubleshooting by allowing each layer to operate independently while interacting with the layers directly above and below it.

The most widely adopted models for protocol layering are the OSI (Open Systems Interconnection) model and the TCP/IP (Transmission Control Protocol/Internet Protocol) model. The OSI model is a theoretical framework comprising seven layers, starting from the physical transmission of bits at the lowest layer (Physical Layer) up to the application-specific services provided to end-users at the highest layer (Application Layer). The TCP/IP model is a more practical, four-layer model that forms the foundation of the internet. It combines some functions of the OSI model into fewer layers.

Each layer in these models defines a set of protocols, which are rules and conventions governing communication. When data is sent, it typically passes down through the layers, with each layer adding its own header or trailer information (encapsulation). When data is received, it travels up through the layers, with each layer removing its corresponding header or trailer (de-encapsulation) until the original data is presented to the application. This modularity allows for flexibility, as protocols at one layer can be changed without affecting other layers, as long as the interface between the layers remains the same.