Background: this is (I think) effectively a USB hub, with built in ethernet. This is the circuit as it is being used in the Raspberry Pi B rev. 2
The USB+ from the upstream port (0) is connected to the USB+ on only one of the two downstream ports (3) through a 360R resistor [seen in the very middle of the image]. The USB- is similarly connected to the same downstream port (but the - line).
My questions - why is this being done, and why to that particular port? Could it be done to the other port (2), or both of them, or none?
The datasheet for the LAN controller is here: http://ww1.microchip.com/downloads/en/DeviceDoc/9512.pdf
The whole schematic is here: https://www.raspberrypi.org/wp-content/uploads/2012/10/Raspberry-Pi-R2.0-Schematics-Issue2.2_027.pdf
The part I have taken this image from is on page 3 of the schematic.