Je potreba USB bridge (relizovany napr. specialnim kabelem, nebo to muze byt implementovano primo v USB root hubu napr. na zakladnich deskach MSI se to jmenuje PC2PC).

Tady je oficialni vyjadreni z usb.org (aneb A-A je nejlepsi cesta jak si zkratovat napajeci zdroje v PC)...

Q5: How can I connect two PCs to each other with USB?
A5: You need a specialized USB peripheral known as a USB bridge (sometimes called a USB to USB adapter) to do this. Anchor Chips and e-Tek labs, among others, make USB bridges.

Q6: You mean I can't make a direct cable connection like a null modem?
A6: Correct. In fact, if you try this with an illegal A to A USB cable, you'll short the two PCs' power supplies together, possibly destroying one or both machines or causing a fire hazard. Even there were no danger to the machines from the problem with two power supplies, there still wouldn't be any way to get the two PCs talking to each other, since USB doesn't support that particular kind of communication. A reasonably priced solution to handle this need is the USB bridge.

Q7: So why do people make A to A cables, anyway? What kinds of cables do I need to connect USB devices together?
A7: A number of cable vendors seem to have reached the conclusion that USB is like a PC's serial port, only faster, so you need all sorts of special hardware to create the USB connection you need to make. This is completely incorrect. The only kind of cables you'll ever need to connect normal USB products are A to B cables, A to mini B cables or mini A to mini B cables of various lengths. Some special kinds of devices use nonstandard connectors and so come with their own special cable.

Q8: What if I want to network a whole bunch of PCs together with USB?
A8: If you need to connect just a few machines, USB bridges and a hub or two will work. USB was not designed to be a LAN, however, and there are certain safety hazards associated with trying to use USB with large numbers of PCs. There's also a large performance penalty compared to a real LAN. If you need a LAN, use a technology intended to be used as a LAN, such as Ethernet.