OSI Model

The Open Systems Interconnection (OSI) model is a conceptual framework used to understand and standardize the functions of a telecommunication or computing system.

The 7 Layers

1. Physical Layer: Raw bit stream over a physical medium (e.g., cables, switches).
2. Data Link Layer: Node-to-node data transfer (e.g., MAC addresses, switches).
3. Network Layer: Routing of data paths (e.g., IP addresses, routers).
4. Transport Layer: Reliable transmission of data segments (e.g., TCP, UDP).
5. Session Layer: Managing communication sessions.
6. Presentation Layer: Data formatting and encryption.
7. Application Layer: Network applications (e.g., HTTP, FTP, SMTP).

Understanding the OSI model is essential for troubleshooting networks and understanding where specific security controls apply. It closely relates to the TCP IP Model.