This illustration depicts a data transfer over a reliable channel. At the top of the image are two computers positioned side-by-side, representing the sender on the left and the receiver on the right. Below the two computers are three layers: the first layer is labeled "Application layer;" the second is labeled "Transport layer;" the third is labeled "Network layer."

Beneath the sender's computer is an oval labeled "Sending process," from which the data is sent. The data here is represented by a small blue rectangle, labeled "Data." A blue arrow extends vertically downward from the sender and passes through the application layer. In the transport layer, the blue arrow makes a 90-degree turn to the right and passes horizontally through the transport layer. In the transport layer is a tube labeled "Reliable channel" through which the blue arrow passes. Then it makes a 90-degree turn to the left and extends vertically upwards through the transport layer and through the application layer and into an oval labeled "Receiver process."