In this illustration, the four switches look like discs and form a square. The first is connected to the second by four links, shown here as black lines or cables; the second is connected to the third by four links, the third to the fourth, and the fourth to the first. Each switch has four circuits, shown here as simple lines radiating outward. The first, second, and third switches have desktop computers next to them. The first computer, at the top left corner of the square, is connected to one of the circuits, which is shown as a blue highlight. The blue highlight travels rightward through one of the circuits and across one of the links, through the second switch and downward through a link to the third switch in the bottom right corner of the square, and out a circuit to a second desktop computer.