Implementing Cisco Networking Solutions

Basic OSI reference model

The communication entities perform a variety of different functions during the communication process. These functions range from creating a message, formatting the message, adding information that can help detect errors during transmission, sending the data on the physical medium, and so on.

The OSI reference model defines a layered model for interconnecting systems, with seven layers. The layered approach allows the model to group similar functions within a single layer, and provides standard interfaces allowing the various layers to talk to each other.

Figure 1 shows the seven layers of the OSI model. It is important to note that the reference model defines only the functions of each layer, and the interfaces with ...