Todos los Dispositivos USB se adjuntan al Sistema a través de Dispositivos especializados conocidos como Hubs. Hubs have status bits that are used to report the attachment or removal of a USB device on one of its ports. The host queries the hub to retrieve these bits. In the case of an attachment, the host enables the port and addresses the USB device through the device’s control pipe at the default address.

The host assigns a unique USB address to the device and then determines if the newly attached USB device is a hub or a function. The host establishes its end of the control pipe for the USB device using the assigned USB address and endpoint number zero.

If the attached USB device is a hub and USB devices are attached to its ports, then the above procedure is followed for each of the attached USB devices.

If the attached USB device is a function, then attachment notifications will be handled by host software that is appropriate for the function.