PL-2301 USB-USB Bridge Controller
is a low-cost high-performance single chip solution that provides bi-directional connectivity between any standard USB compliant host systems...
PL-2302 USB-USB Network Bridge Controller
provides a quick and easy solution to construct a network via USB port instead of any Network Interface Card...
PL-2311 USB-Ethernet Bridge Controller
integrates a 802.3u fast Ethernet controller with a USB interface for the host link...
PL-2501 Hi-Speed Host to Host Bridge Controller
is a single chip Hi-Speed USB Host-to-Host Bridge Controller. With PL-2501 embedded cable, users can quickly transfer large amount and large size of files directly from one PC to another.
basically, this problem is still solved by the software. this asic should provide a nic driver, and it works similar to that from Ethernet type network. thus it is taken as one nic device from os's point of view. why this asic exists? i only can say where can we find a device w/ 2 usb ports?