NetzwerkSchichten

NetzwerkSchichten (German: network layers) refers to the conceptual division of communication functions in a computer network into separate, stacked layers. Each layer provides services to the layer above and uses services from the layer below, which simplifies design, interoperability and troubleshooting by isolating responsibilities such as physical signaling, error detection, routing and application protocols.

Two widely used models illustrate layer concepts: the seven-layer OSI model (Physical, Data Link, Network, Transport, Session, Presentation, Application) and the simpler Internet or TCP/IP suite (link, internet, transport, application). In practice, implementations combine or omit some OSI layers: for example, HTTP operates at the application layer, TCP at the transport layer, IP at the network layer, and Ethernet at the link and physical layers.

Key mechanisms associated with network layers include encapsulation (wrapping data with protocol-specific headers), abstraction (hiding lower-layer details), and modularity (allowing independent development of protocols and hardware). Layered architecture supports interoperability across vendors, scalability of networks, and clearer fault isolation during troubleshooting.

Criticisms of strict layering note inefficiencies, redundant functionality across layers, and mismatches between theoretical models and real-world protocols. Despite that, the layered approach remains a central organizing principle in networking education, protocol design and network engineering practice.