The network topology is as follows:

• The 3 PCs are connected to a switch (or hub) device.
• The first IOU (IOU1) is connected to the switch (or hub).
• The second IOU (IOU2) is connected to the first IOU (IOU1).
• The third IOU (IOU3) is connected to the switch (or hub).
• The server is connected to the second IOU (IOU2).

In this setup, the three PCs represent end-user devices, such as desktops or laptops, and the server represents a central resource, such as a web server or a database server. The IOUs are virtual routers running the IOS operating system.

By connecting the devices in this way, you can simulate a small network environment where the PCs can communicate with each other and access resources on the server. The IOUs can be configured to route traffic between the devices, apply security policies, and perform other network functions.