The OSI seven-layer model is an important structural framework for modern network communications, with each layer interacting with the others during data transmission to ensure the integrity and reliability of information. The model serves to manage complex communication processes and facilitate compatibility between different systems, making networks more reliable and efficient.
A protocol is an internationally standardized commitment to accurately and reliably transmit information from a sender to a receiver in a communication situation. In order for these protocols to be applied in real-world communication situations, a standardized logical structure is required, the most representative of which is the OSI seven-layer model, which divides communication functions into seven levels. In this case, the information that the sender wants to send is sent through steps 1 through 7 of the transmission process and delivered to the receiver through steps 1 through 7 of the reception process.
The OSI seven-layer model plays an important role in organizing the complex communication process and helping various network equipment and software to be compatible with each other. The main purpose of the model is to ensure seamless communication between different systems by dividing the communication process into different layers, each of which has a specific role to play. This makes it easier for network architects and developers to diagnose and resolve issues that arise at each layer. This layered approach reduces the complexity of the network and makes the development and maintenance of communication systems more efficient.
Steps 5 through 7 of the model have in common that the information is addressed from a software perspective, which is referred to as the upper layer. The top level, stage 7, is called the application layer and is where the sender or software accesses the network. For example, a sender might access a site and log in. The applications that the user accesses, such as a web browser or email client, are often involved at this stage, and these programs mediate the interaction between the user and the network. The sixth layer, the representation layer, converts the information you want to send into computer-standard formats such as strings and numbers so that it is compatible with other computers. It also compresses the information during transmission and decompresses it during reception. For example, when sending a graphic or video file, compression is used to reduce the file size, and decompression is required at the receiving end to restore the original data. This process allows for efficient use of network bandwidth and reduces data transfer times. Step 5, the session layer, adds checkpoints to the information being sent to provide a sort of reference point for retransmission in the event of an error. This layer is also responsible for establishing, maintaining, and terminating the communication connection between the sender and receiver, which is essential to ensure reliable data transfer between the two systems.
In contrast, layers 1 through 4 are referred to as lower layers, but they all have in common that they function on the physical side to allow information to pass through. The fourth of these, the transport layer, is responsible for dividing the information into units called “frames” and then inserting the recipient’s internet address into each frame to ensure that the information is delivered correctly. This is where data flow control and error control take place, which is important for the reliability of the network. The third layer, the network layer, is responsible for establishing the optimal path for the fastest and most secure delivery of the information to the recipient. At this stage, network devices such as routers determine the path of data packets and use packet switching to forward the information to its destination. Once the path is established, the second stage, the data link layer, converts the frame-by-frame information into bits, represented by binary 0s and 1s that can be physically transmitted, and sends them to the physical layer. At the data link layer, error detection and correction mechanisms are applied to minimize the damage that can occur during data transmission and ensure reliability. Finally, the physical layer checks the mechanical conditions, such as the type of cable and electrical signals used to send the information, and if everything is in order, the information is sent over the cable. The physical layer is where data is actually transmitted over the transmission medium, which can include electrical signals, light signals, radio frequencies, and more.
Except for the physical layer, which is connected by cables in the process of sending and receiving such information, the n-layer of transmission and the n-layer of reception are not directly connected. However, in order to accurately convey the information, the n layers must functionally interact around the protocols of each layer, so each n layer in the transmission must add its protocols to the information. The protocols added by each layer are interpreted by the corresponding layer of the receiver, and then immediately discarded, leaving only the information that the receiver wants to receive in step 7. This approach is essential to maintaining the integrity and authenticity of information in network communications, allowing for seamless communication between sender and receiver.
The OSI seven-layer model can be used in a variety of network environments, and the same principles can be applied to small, internal networks as well as large networks like the Internet. It is an important tool for network design and implementation, and is an essential model for network engineers and IT professionals to understand and troubleshoot systems.
