OSI stands for Open Systems Interconnection. It refers to a conceptual framework that standardizes the functions and interactions of different computer systems and networks to allow them to communicate with each other. OSI is a reference model that divides the communication process into seven layers, each with specific functions and protocols.
The seven layers of the OSI model are:
1. Physical Layer: This is the lowest layer, responsible for the transmission and reception of raw bitstream over a physical medium, such as cables.
2. Data Link Layer: This layer ensures reliable data transfer between nodes on the same network segment. It detects and corrects errors that may occur during transmission.
3. Network Layer: The network layer handles the addressing and routing of data packets across multiple networks. It establishes logical connections, determines the best path for data transfer, and handles network congestion.
4. Transport Layer: This layer ensures reliable end-to-end transmission of data. It segments larger data chunks into smaller packets and ensures they are delivered error-free and in the correct order.
5. Session Layer: The session layer establishes, manages, and terminates connections between applications on different devices. It provides mechanisms for synchronization and allows for session recovery in case of interruptions.
6. Presentation Layer: This layer translates, encrypts, or compresses data into a format acceptable by the application layer. It handles data conversion and supports common data representation formats.
7. Application Layer: The application layer interacts directly with end-user applications. It defines protocols for specific applications, such as email protocols (SMTP), file transfer protocols (FTP), and Hypertext Transfer Protocol (HTTP) for web browsing.
The OSI model serves as a reference for network architecture design, ensuring compatibility and interoperability between different systems and networks.
