OSI Reference Model
Open Systems Interconnection model is an important concept in networking. The main function of OSI is to help data to be transferred through different computers in the Network.
OSI divides the task to different layers, each and every layers as its own protocols.
OSI is divided into 7 layers
Application Layer |
Presentation Layer |
Session Layer |
Transport layer |
Network layer |
Data Link layer |
Physical layer |
Application layer:
Application layer identifies or takes the responsibility for identifying the existing system or check whether there is sufficient resources for communication.
Performs tasks like file, print, database services.
Presentation layer:
Responsible for data translation and formatting data.
Performs tasks like data encryption and data decryption, compression, translation into machine readable language.
Session layer:
Responsible for setting and managing time or session for each packets.
Transport layer:
Provides end-to-end data transport services and check whether the connection is reliable or unreliable and perform error correction.
Network layer:
Logical connection or path is identified. Routers are identified and data packets are transferred.
Shortest path or the best path for transmitting data packets are identified.
Data Link layer:
Provides physical transmission of data and performs error detection. Data link provides confidence to ensure that the data are delivered to proper device in the network.
Packets->Bytes->Frames
Physical layer:Identifies the physical media such as Ethernet and physical cable that is used for transmitting data, Network topology are identified and packets are send and received in this layer.
Physical layers is most important layer in OSI model which is responsible for sending bits and receiving bits.