Bus-powered hubs use power from the USB bus to which they are connected, to power devices connected to them. Special care must be taken to not overload these hubs, because the power these hubs offer to their downstream devices is limited.
Starting in the Solaris 10 6/06 release, power budgeting is implemented for USB devices. This feature has the following limitations:
Cascading two bus-powered hubs is prohibited.
Each bus-powered hub is allowed a maximum of 100 mA only for each port.
Only self-powered or low bus-powered devices are allowed to connect to a bus-powered hub. High bus-powered devices are denied the connection. Some hubs or devices can report a false power source, such that the connection might be unpredictable.