What is the OSI model?|| Explained in details||

 

 The OSI model is a layered framework for the design of network systems that design allows for communication across all types of computer systems. It consists of seven separate but related layers, each of which defines a segment of the process of moving information across a network. Understanding the fundamentals of the OSI model provides a solid basis for the exploration of data communication.

Layered Architecture build of seven ordered layers

physical layer

data link layer

network layer 

transport layer

session layer

presentation layer

application layer

As the message transfer from one device to another device, it may pass through many intermediate nodes. These intermediate nodes usually involve only the 1st three layers of OSI models. In developing the model, the designers distilled the process of transmitting data down to its most fundamental elements. They identified which networking function had related users and collected functions into discrete groups that became the layers. Each layer defines a family of functions distinct from those of the other layers. By defining and localizing functionality is that fashion, the designer created an architecture is that fashion, the designers created an architecture that is both comprehensive and flexible, Most important, the OSI model allows complete transparency between otherwise incompatible systems.

 

Physical layer: The physical layer coordinates the function required to transmit a bit of stream over the physical medium.

It deals with mechanical and physical specifications of the interface and transmission medium. It also defines the procedures and functions that physical devices have to perform for transmission to occur. 

Data Link Layer: It transforms the physical layer, a raw transmission facility, into a reliable link. It is also responsible for node-to-node delivery. It makes the physical layer error-free to the network layer. 

Network Layer: The network layer is responsible for source to destination delivery of a packet possibly across multiple networks(link). Where the data link layer oversees the delivery of the packet between two systems on the same network. 

Transport layer: responsible for source to destination delivery of the entire message. 

Session layer: THes session layer is the network dialog controller. It establishes, maintains, and synchronizes the interaction between communicating systems.

Presentation Layer: The presentation layer is concerned with the syntax and semantics of the information exchange between two systems. this layer up translation, encryption, and compression.

Application layer: It enables the user, whether human or software, to access the network. It provides user interfaces and support for services such as electronic mail, remote access, and transfer, shared database management, shared management, and another type of distribution services.