What Is An OSI MODEL?

The OSI model is a standard reference model for networking that divides the process of communication between two devices into seven layers, each of which provides a specific set of functions. The purpose of the OSI model is to provide a modular and standardized way of describing how communication works in a computer network.

The seven layers of the OSI model are:

1. Physical Layer: This layer deals with the physical transmission of data over a network, including the electrical and mechanical interfaces, and the transmission of signals.

2. Data Link Layer: This layer provides reliable transmission of data frames over the physical layer. It is responsible for error detection and correction, flow control, and media access control.

3. Network Layer: This layer is responsible for routing packets from source to destination. It provides IP addressing and routing protocols such as OSPF and BGP.

4. Transport Layer: This layer provides end-to-end reliable communication between applications. It is responsible for flow control, segmentation and reassembly, and congestion control.

5. Session Layer: This layer is responsible for managing sessions between applications. It provides functions such as establishing, maintaining, and terminating connections.

6. Presentation Layer: This layer deals with the format of the data, including encryption, compression, and conversion of data to a common format.

7. Application Layer: This layer provides the interface between the application software and the underlying communication services. It provides services such as HTTP, FTP, and Telnet.

Each layer of the OSI model communicates with the adjacent layers to provide reliable, efficient communication between networked devices. Understanding the different layers of the OSI model and the functions they provide is crucial for anyone working in computer networking.