Networking is the ability to exchange data between two or more applications across two or more computers. Because each computer on the network may be different (a Macintosh, a PC, a Sun workstation), networks must not only transport data,
they must translate protocols between dissimilar computers to assure compatibility at the hardware and software level.
To conceptualize the many translation steps required by the network server to successfully link computers, we can use the OSI network model. The model's purpose is to outline the logical processes required to exchange data between potentially dissimilar computers on a network.
The OSI (or Open Systems Interconnection) model conceived by the International Standards Organization (ISO), a U.N. agency, is a seven-layer framework for implementing protocols or tasks. The following series of images shows the function of each layer.
In the context of the OSI Network Model, "Layered Protocols" refer to the way in which different network protocols are organized into distinct layers. Each layer of the OSI model has its own set of protocols that operate independently of the protocols in other layers, but also work together to provide end-to-end communication between devices on a network. The OSI model consists of seven layers, each of which is responsible for a specific set of functions related to network communication. Each layer uses a set of protocols that are specific to that layer, and that define how data is transmitted, received, and processed at that layer. These protocols are often referred to as "layered protocols."
For example, the Application layer of the OSI model uses protocols such as HTTP, FTP, and SMTP to provide services such as email, file transfer, and web browsing. The Transport layer uses protocols such as TCP and UDP to provide reliable, end-to-end data transmission between applications. The Network layer uses protocols such as IP and ICMP to provide routing and addressing services between different networks.
Each layer of the OSI model communicates with the layer above and below it, using standardized protocols and interfaces. This allows different devices on a network to communicate with each other using a common set of protocols and interfaces, regardless of the specific hardware or software they are using.
Overall, the concept of layered protocols in the OSI model helps to ensure that network communication is standardized, efficient, and reliable, and that devices on a network can communicate with each other in a consistent and predictable way.
- Protocols connect entities on same level, within the layer
- Higher layers use services provided by lower layers
- Layers are independent and defined by interface provided to the higher layer and required from the lower layer