Daisy chaining in USB

Never really paid that much thought to it... until today, at least.

What is daisy chaining w.r.t the USB bus standard?

Daisy chaining can be depicted as -

USB port on computer --- USB device --- USB device --- .... ---- Terminator

It has also been very aptly defined in the 'daisy chaining' wiki @
http://en.wikipedia.org/wiki/Daisy_chain

USB standard says that you can have upto 127 devices attached per USB port in a daisychain. But then, it also puts a limit on the maximum number of hops permitted. This limit is FAR lesser than the 127 devices that can be connected per USB port. So, the question is how do we explain this contradiction? Simple, we daisy chain POWERED USB hubs and each of these powered hubs is allowed to carry multiple USB devices. This has been better depicted in the image on the left.

NOTE - If tomorrow, you choose to attach two USB hubs to a single USB hub, in turn connected to a single USB port on the computer, the resultant network will be said to have a 'Star topology'. It WON'T be a daisychain.

This concept will be equally valid for the Firewire standard. The only difference is that it allows upto 16 hops and 63 devices per Firewire port.