Protocol and Protocol Hierarchies

A protocol is a set of rules and conventions agreed upon and followed by the communicating entities for data communication. A protocol outlines the what, how, and when of a communication.

Three Aspects of a Protocol

• Syntax − It defines the format of data that is to be sent or received.

• Semantics − It defines the meaning of each section of bits that are transferred.

• Timing − It defines the time at which data is transferred as well as the speed at which it is transferred.

Protocol Hierarchies

Most networks are organized as a stack of layers, one on top of another. The number of layers and their names vary from network to network. Each layer has a specified function and adheres to specified protocols, forming a protocol stack.

How Protocol Hierarchies Work

When Device A wants to send a message to Device B, the data passes through each layer from top to bottom. Each layer performs specific functions on the data and passes it to the layer below. At the physical layer, the bit stream travels through the physical medium to the receiving device.

At Device B, each layer performs its functions according to the protocol shared with its peer layer on Device A, then passes the processed data to the layer above. This continues until the original message reaches the application layer of Device B.

Key Terms in Protocol Hierarchies

Conclusion

Protocols define the rules for communication through syntax, semantics, and timing. Networks use layered protocol hierarchies where each layer has specific functions and communicates with its peer layer on remote devices, enabling reliable data transmission across complex network infrastructures.