USRP2 maxium bandwidth - 100MHz?

Im looking at the USRP2 brochure:

http://www.ettus.com/downloads/ettus_ds_usrp2_v2.pdf

It says:
“A Gigabit Ethernet interface allows applications to
simultaneously send 50 MHz of RF bandwidth in and
out of the USRP2.”
and
“Capable of processing signals up to 100 MHz wide”

OK, so we are capturing 100MHz of bandwidth, using the 2 ADCs at 100MS/s
each (I and Q). If each complex sample is 32 bits, that is 4 bytes per
complex sample. which means we are capturing data at a data rate of
400MB/s.

How does the USRP2 manage to send 400MB/s across gigabit ethernet link
(gigabit = 1000bps = 125MB/s)?