Protocol Data Units (PDU)

Protocol Data Units (PDUs) are the building blocks of data transmission in networks. They are structured packets of information exchanged between different network layers and devices. Each PDU contains specific data and control information necessary for communication, such as headers and trailers, which help identify, route, and interpret the data correctly. Depending on the layer (like physical, data link, or application), PDUs have different formats and names—such as frames, packets, or segments. In essence, PDUs ensure data is properly organized and understood as it moves across a network.