OSI (Open Standard Interconnection) shows how information from one application software in one computer moves to the application software of another computer.
The International Organization for Standardisation (IOS) developed the OSI model in 1984. It is now a standard procedure for inter-computer communication.
OSI is a protocol through which two computers exchange information with each other.
Layer of OSI
The layers of OSI are
- Physical layer
- Data-link layer
- Network layer
- Transport layer
- Session layer
- Presentation layer
- Application layer
Application layer
In this layer, Data is generated to be sent to another computer. Data is created with the help of application software.
Humans interact with computers and make data. And the application can access the network services.
Presentation layer
In this layer, Make sure the data is ready to be sent. Syntax and semantics of information are the main concerns of the presentation layer.
The Presentation layer ensures data is in a usable and readable format. And information is in encrypted format.
Session layer
In this layer, a Connection between two computers is established and synchronized. This layer also ensures security and authentication. The Session layer Maintains connection and is responsible for controlling ports and sessions.
This layer creates some checkpoints. If some error occurs in the middle of the transmitting process, So the process starts from the last checkpoint unless from starting. The communication between two systems is in the form of either half duplex or full duplex.
Transport layer
In this layer, Data travels from one system to another system. After the successful transfer of data, the Transport layer provides acknowledgment. It also adds source and destination port numbers to the data.
The Transport layer transmits data using transmission protocols UDP and TCP. In the Transport layer, Data is known as Segments. The transport layer ensures data is received by the end-user without any error.
Network layer
In this layer, a Suitable route is decided to transfer data from source to destination. In the network layer, data is known as Packets. The network layer puts the sender and receiver IP addresses in the header of the Packets.
This layer used an addressing system for differentiating between different systems. The network layer decides which physical path the data is going to take.
Data-link layer
It is the responsibility of this layer when data is in the network to transfer data to the destination using the MAC address. This layer also tracks the location of the system on the network.
The Data-link layer contains information about the format of data on the network. This layer divides the packets into frames according to frame size.
Physical layer
This layer is responsible for the actual connection between systems. This layer decides the flow of data either in simplex, half, or full duplex.
The Physical layer transmits raw stream over a physical medium. This layer also knows about how systems are connected. This layer helps in maintaining and deactivating the physical connection.