It is comprised of seven layers and each layer carries out a peculiar network function. The OSI model was developed by the International Organisation for standardization (ISO) in 1984, and it is now contemplated as an architectural model for inter-computer communications. OSI model furcates the whole task into seven smaller and attainable tasks. Each layer is allocated a particular task. Each layer is free-standing so that tasks conveyed to each layer can be achieved severally.
Characteristics Of OSI Model :
-The OSI Model is ramified into two layers, upper layers, and lower layers
- The upper layer of the OSI model predominantly deals with the application-related issues, and they are administered only on software. The application layer is abutted to the end-user. Both the end-user and the application layer interact with the software applications. An upper layer refers to the layer just above another layer.
-The lower layer of the OSI model deals with the data transport issues. The data link layer and the physical layer are effectuated in hardware and software. The physical layer is the lowest layer of the OSI model and is contiguous to the physical medium. The physical layer is principally accountable for placing the information on the physical medium.
Functions of the OSI Layers
There are seven OSI layers. Each layer has different functions. A list of seven layers is as follows :
1. Physical layer
2. Data-Link Layer
3. Network Layer
4. Transport Layer
5. Session Layer
6. Presentation Layer
7. Application Layer
The function of Physical Layer: Line Configuration, Data Transmission, Topology, and Signals
The Function of Data-Link Layer: This layer is authoritative for the error-free transfer of data frames.
The Function of Network Layer: Internetworking, Addressing, Routing, and Packetizing
The Function of Transport Layer: Service point addressing, Segmentation and reassembly, Connection control, Flow control, and Error Control.
The Function of Session Layer: Dialogue and Synchronization
The Function of Presentation Layer: Translation, Encryption, and Compression
The Function of Application Layer: File transfer, access, and management (FTAM), Mail Services, and Directory services.
