International Standard Organization
The ISO develop a model what they called Open System Interconnection (OSI).This model proposed that all network protocol should consist of seven distinct layers. SO is multinational body dedicated to worldwide agreement on international standards. The OSI model is not a protocol, it is a model for understanding and designing a network architecture that is flexible, robust, and interoperable.
Open System Interconnection (OSI)-
The OSI model is a concept that describes how data communication should take place in network. It divides the process into the seven groups called layers. Numerous protocols may exist in each layer. In a given message between user there will be a flow of data through each layer at one end down through the layer in that computer and , at the other end, when the message arrive another flow of data up to through the layer in the receiving computer and ultimately to the end users.
Each layer of OSI model provides its own set of functions; it is possible to group the layer into two distinct categories. The first four layer-Physical layer, Data link layer, Nerwork layer, Transport layer provide end to end service necessary for the transfer of data between the systems. These layers provide the protocol associated with the communication network used to link two computers together. The top three layer-Application layer, Presentation layer and Session layer provide the application services required for the exchange of the information. It also known as Layered Architecture.
Advantage of OSI-
1. It divides the network communication process into the smaller and simpler components.
2. It encourages industry standardization by defining what functions occur at each layer of the model.
3. It allows various types of network hardware and software to communicate.
4. It present changes in one layer from affecting other layers.
5. OSI also provides a framework for creating and implementing networking standard devices and inteworking schemes.
OSI Network Architecture-
Application Layer
Presentation layer
Session layer
Transport layer
Network layer
Data link layer
Physical layer
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