RCM3000: U10 utility !

Hi,

Currently, I am designing a board with a Rabbit 3000.
I need the Ethernet link (RTL8019AS).
My starting point is the RCM3000 schematic but I cannot find the utility of U10 (transceiver: 74LCX245).

In which situation is this device required ? Where is this information available ?

Thank you in advance

Nicolas