OSI reference model

The OSI reference model of the International Standards Organization(ISO) was designed from 1977 as a basis for the formation of communication standards. The aim of the Open Systems Interconnection (OSI) is communication in heterogeneous networks, in particular between different computer worlds on the basis of application-supporting basic services. These basic services are, for example, file transfer, the virtualterminal, remote access tofiles and the exchange of electronic mail. For these and all other communication applications, in addition to the actual application data, additional structural and procedural information is required, which is defined as OSI protocols. In the OSI reference model, communication is realized by service elements or work units that have a fixed location and a defined task. The service elements can be implemented in terms of hardware, firmware and software. Elements with comparable functions can reside on different systems and are arranged in layers. Each layer describes the functions of the elements. An element that implements objects and provides operations is called an entity. Accordingly,in the reference structure the Division of the architecture into layers, Division of layers into work units,Cooperation of working units within a layer, cooperation of the working units in neighboring layers and the Cooperation of working entities in the same layers of different systems. must be defined. From top to bottom, the interface between two layers is a principal/contractor interface. A work unit within a shift performs a certain service. In doing so, it may use tools that are available to it locally or that are provided by a work unit on the next lower layer. In addition to this interface, it is important to maintain a set of rules with like work units on another system. Such a set of rules is called a protocol. The OSI reference model is divided into seven layers and is therefore also referred to as the 7-layer model OSI reference model with the transport and application-oriented layers The layers can be divided into two groups: the transport-oriented and the application-oriented layers. The transport-oriented layers include layers 1 to 4; the application-oriented layers include layers 5 to 7. These layers each represent the framework for standards and describe objects, operations, work units and protocols in a simplified and general manner. The descriptions are then refined in individual communication standards for the individual layers. The seven layers of the OSI reference model. The lowest layer 1 is the physical layer. It defines the communication tools for transmission. The data linklayer

Englisch:	OSI reference model
Updated at:	10.02.2017
#Words:	407
Links:	open systems interconnection (OSI), international organization for standardization (ISO), communication (COM), computer, application (app)
Translations:	DE
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