What is OSI reference model

The international standards organization (ISO) in 1983, developed OSI model as a first step toward international standardization of the protocols used in the various layers. As it deals with connecting open systems ,that are open for communication with other systems, the model is also called ISO OSI Reference model.

• Physical layer
• Data Link layer
• Network layer
• Transport layer
• Session layer
• Presentation layer
• Application layer

The principal behind arriving these layers are as follows-

• A layer should be created where a different level of abstraction is needed.
• Each layer should perform a well-defined function.
• The function of each layer should be chosen with defining internationally standardized protocols.
• They layer boundaries should be chosen such that the information flow across interfaces in minimum
• The Number of layer should be such that, it is large enough that distinct need not be thrown together in the same layer out of necessity ,and small enough that the architecture does not become unwieldy.