Transport layer protocols

The transport layer (Layer 4) is responsible for transporting data between network devices. It is interesting since this layer operates the two most well-known protocols, TCP and UDP. While TCP is characterized by reliability, UDP is characterized by the best effort. That said, altogether, the transport layer adds reliability, flow control, transmission error control, and best effort to data transmission. The term segment is used to represent the PDU at this layer, as shown in Figure 2.11. In this layer, the following communication protocols operate:

• TCP
• UDP