Layer 3 - Transport Layer

The transport layer is  responsible for reliable network communication between systems. The transport layer provides mechanisms for the
establishment, maintenance, and termination of virtual circuits, transport fault detection and recovery, and information flow control.

The transport layer is the part of the railroad system that makes sure that products get to their destinations intact and without damage. If a box arrives at the destination in a damaged form, an order is sent back to send a new one.