Open System Interconnection Reference Model or OSI Reference Model or OSI model is actually a conceptual description for communications and computer Design Network layer protocol. It was created as part of open systems interconnection, or OSI initiative. In its most basic network architecture into seven segments of different layers:. Application, Presentation, Session, data transport, network, link and physical layers
As a result, it is often referred to as the OSI Seven layer model. A layer is a collection of functions similar theory, which provides services layer immediately above, and receives service from the layer below. In each layer an organization providing services to the events of the upper layer and application layer services from below. An example of this is related to a layer that provides communication errors in a network offering, then the path is needed above claims, that, while the next lower layer is called to send and receive packets that make up about content.
working on a model of network architecture layers began in 1977.
Meanwhile, the International Organization for Standardization, ISO, began to develop OSI framework architecture. OSI has two main parts: an abstract model of the network, called the Basic Reference Model, or seven-layer model and a set of specific protocols. It is important to note that the standard documents that describe OSI model can be downloaded from the ITU-T X.200-series Recommendations. A number of protocol specifications can be achieved, also as part of ITU-T Series X equivalent ISO and ISO / IEC standards for the OSI model is available from ISO, but not all of them are available free of charge.Each area of OSI design evolved from experiences with Cyclades network, which also had a great influence on shaping the Internet. The new design has been carefully documented in ISO 7498 and its several additions. In the latter model, a network segmented into teams. Within each layer, showing one or more units of functionality. Each unit will interact directly only with the layer below it, and allows use of the layer above.
protocol allows a host device to interact with a similar unit in the same layer in another host. Service definitions describes the ideal of a (N)-layer with a layer (N-1), where N is one of the seven layers of protocols operating in the local host.
Neither OSI Reference Model or OSI protocols designate a programming interface, but without intent Abstract Service specifications. Protocol Specification specifies interfaces between multiple computers, but the interface software in computer technology is implementation specific.
For example, Microsoft Windows Winsock “, and Unix’s Berkeley sockets and V transport system Layer Interface, are interfaces between applications (layer 5 and above) and transport (Layer 4). NDIS and ODI are interfaces between media Layer 2 network protocol, the Layer 3 interface standards, except the physical layer media estimated implementations of OSI service specifications.