OSI Model Computer Network What Is in 2 minutes

What is the conceptual network OSI MODEL, presented in 2 minutes of concepts. #MAZERtheDEV #NETWORKPROTOCOLS

The Open Systems Interconnection model (#OSI model) is a conceptual model that characterises and standardises the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technology. Its goal is the interoperability of diverse communication systems with standard communication protocols.

The model partitions the flow of data in a communication system into seven abstraction layers, from the physical implementation of transmitting bits across a communications medium to the highest-level representation of data of a distributed application. 

Each intermediate layer serves a class of functionality to the layer above it and is served by the layer below it. Classes of functionality are realized in software by standardized communication protocols.

The seven layers of OSI Model are: Application, Presentation, Session, Transport, Network, Data link and Physical.

Communication protocols enable an entity in one host to interact with a corresponding entity at the same layer in another host. 

At each level N, two entities at the communicating devices exchange protocol data units (PDUs). 

Each PDU contains a payload, called the service data unit (SDU), along with protocol-related headers or footers.

Data processing proceeds as follows:

The data is composed at the topmost layer of the transmitting device into a protocol data unit (PDU).

The PDU is passed to layer N-1, where it is known as the service data unit (SDU).

The SDU is concatenated with a header, a footer, or both, producing a layer N-1 PDU. It is then passed to layer N-2.

The process continues until the lowermost level, from which the data is transmitted to the receiving device.

At the receiving device the data is passed from the lowest to the highest layer as a series of SDUs, being successively stripped from each layer's header or footer until reaching the topmost layer, where the last of the data is consumed.