OSI Model

In 1970, the International Organization for Standardization (ISO) has developed a seven-layer model, LAN architectures. In parallel, the ISO has developed a protocol to fit the model. Since then, other models such as the five-layer TCP / IP model was developed, but the OSI model is still used to map and categorize protocols because of the clear and unambiguous manner representative network functions. The OSI model contain 7 layers

7)Application Layer:



• To allow access to network resources.

• Enables the user either human or software to access the network.

• It provides user interface and support for the services such as Electronic mail, Remote File se Management and other services.

6)Presentation Layer



• To translate, encrypt, and compress data.

• This layer is connected with Semantic and syntax of info exchange between two systems.

• Function of presentation Layer are

? Translation

? Encryption

? Compression

5)Session Layer



• To establish, manage, and terminate sessions.

• It is the network dialogue controller.

• Establishes, Maintains, and synchronizes the interaction between communicating systems.

4) Transport Layer



• To provide reliable end-to-end message delivery and error recovery.

• Responsible for source to destination delivery for entire message.

• Network layer oversees source-to-destination delivery of the entire packets but it does not recognize any relationship b/w those packets.

3)Network Layer



• Responsible for source –to-destination.

• Dl Layer oversees the delivery of data between 2 systems on the same network.

• Network Layer ensures that each packet gets from its point of origin to its final destination.

2) Data link layer



• Transforms Physical layer which is transmission facility to a reliable link

• Responsible for Node to Node delivery.

• Make Physical layer look error free to the upper layer.

1)Physical Layer



• Coordinates the functions required to transmit a bit stream over a physical medium.

• Deals with electronic and mechanical specification.

• Also defines and function that physical devices and interfaces need to perform for TX.

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