OSI (Open Systems Interconnection)
OSI (Open Systems Interconnection) model describes seven layers through which computer systems communicate over a network.
Remember that, the modern Internet is not based on OSI, but on TCP/IP model (Transmission Control Protocol/ Internet Protocol)
Physical Layer: The physical layer is concerned with the physical transmission of data over a network. It defines the electrical, mechanical, and procedural aspects of the network hardware and cabling.
Data Link Layer: The data link layer establishes and maintains reliable links between adjacent nodes on a network. It handles the physical addressing of data packets and error detection and correction.
Network Layer: The network layer is responsible for logical addressing and routing of data between different networks. It determines the best path for data packets to travel from source to destination.
Transport Layer: The transport layer provides end-to-end communication services for applications. It ensures that data is transmitted reliably, efficiently, and securely between communicating devices.
Session Layer: The session layer manages and coordinates communication sessions between applications on different devices. It establishes, maintains, and terminates communication sessions.
Presentation Layer: The presentation layer defines the format and representation of data exchanged between applications. It manages data compression, encryption, and decryption.
Application Layer: The application layer provides services directly to end-users. It specifies how user applications interact with the network and enables users to access network resources and services.
Overall, the OSI model helps to streamline network communication by breaking the process down into smaller and manageable components. By having a clear understanding of the OSI model and how it works, network engineers can work more effectively and efficiently to design, implement, manage, and troubleshoot networks.