Salvatore,
Bandwidth is a little bit in the eye of the beholder. The difference between IP bandwidth (byte of IP protocol per second) and Ethernet bandwidth (Ethernet bytes per second) would depend on whether you are just talking about the bytes sent up from the NIC to the driver or also including the time taken up by the full preamble and trailing CRC and interframe gap. You might want to refer to
http://en.wikipedia.org/wiki/Ethernet#Physical_layer to realise how difficult this is to define precisely without some other statement.
