OSI stands for Open Systems Interconnection. OSI model was developed by the International Organization for Standardization(ISO). It is a reference model for how applications communicate over a network. The OSI model characterizes computing functions into a universal set of rules and requirements in order to support interoperability between different products and software.
The OSI model can be considered as a universal language for computer networking. It is based on the concept of divide and conquers, it splits up the communication system into 7 abstract layers, and the layer is stacked upon the previous layer.
Layers of OSI Model
OSI model has seven layers which are as follows:
- The Physical Layer
- The Data Link Layer
- The Network Layer
- The Transport Layer
- The Session Layer
- The Presentation Layer
- The Application Layer
To learn more about layers, visit Layers of OSI Model
Characteristics
- It is the conceptual model which enables the diverse communication systems to communicate using network.
- It was developed by the ISO (International Organization for Standardization) in 1984.
- It act as an architecture for inter-computer communications.
- It is divided into 7 layers and each layer performs a particular task.
- Each layer is independent of each other and can perform its operations independently.
Advantages
- It is a layered model and each layer is independent in nature. Thus, changes in one layer doesn’t affect the other layers.
- It divides the complex function into smaller parts.
- It is a generic model as it has flexibility to adapt to many protocols.
- It supports both connection-oriented as well as connectionless services.
- It is more secure and adaptable than having all services bundled in the single layer.
Disadvantages
- It is purely a theoretical model and ignores the availability of the resources and technologies. Hence, its practical implementation is somewhat restricted.
- It is very complex. The initial implementation was cumbersome, slow and costly.
- The layers are interdependent on each other, they can’t operate parallely as they have to wait for the data/ packets from the predecessor layer.
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