eth0: Setting full-duplex based on MII #1 link partner capability of 43e1

i use thiese commands

#ifconfig eth0 down
#ifconfig eth0 hw ether (mac)
#ifconfig eth0 up

and after up eht0
it says eth0: Setting full-duplex based on MII #1 link partner capability of 43e1
#ifconfig eth0 |grep HWadrr

what mean that setting full-duplex,and what is the problem guys