What is the name given to the Protocol Data Unit (PDU) at Layer 3?

The Protocol Data Unit (PDU) at Layer 3 of the OSI model is called a packet. Layer 3 is responsible for network routing and addressing, and packets contain both the header information (which includes source and destination IP addresses) and the payload (the actual data being transmitted).

Understanding that packets are crucial for delivering data across different networks helps highlight the importance of Layer 3 in the overall communication process. Routing decisions are made based on the information within these packets, which is essential for enabling devices on different networks to communicate effectively.

Other terms such as frames, bits, and segments refer to PDUs at different layers of the OSI model. Frames are associated with Layer 2 (Data Link layer), bits represent the smallest unit of data at Layer 1 (Physical layer), and segments are linked to Layer 4 (Transport layer). Each layer has its specific PDU which corresponds to its functions and responsibilities within the network communication process.