Layered Network Model

A layered network model is a conceptual framework for describing how communication should be done between different networked devices. The model divides the process of communication into several layers, each of which has a specific function and interacts with the adjacent layers. The most widely used layered network model is the Open Systems Interconnection (OSI) model, which has seven layers:

Physical layer: This is the lowest layer and deals with the physical transmission of data over the network, such as electrical, optical, or radio signals.

Data link layer: This layer is responsible for error detection and correction, and for organizing data into frames for transmission.

Network layer: This layer is responsible for routing data between different networks, using logical addresses to determine the most efficient path.

Transport layer: This layer provides reliable end-to-end delivery of data and manages flow control and congestion control.

Session layer: This layer establishes, manages, and terminates communication sessions between applications.

Presentation layer: This layer is responsible for formatting data so that it can be interpreted by the application layer.

Application layer: This layer provides services to end-user applications, such as email, web browsing, and file transfer.

The main advantage of a layered network model is that it allows different vendors to create products that are interoperable, as long as they comply with the specifications for each layer. Additionally, it allows for easier troubleshooting and isolation of problems, as each layer has a specific function and can be examined separately.