Ciao Luciano
I don't understand your question.
Did you enable NPIV and fport-channel trunk feature on N5k ?
http://www.ccierants.com/2012/09/san-port-channel-with-ucs.html
http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/san_switching/513_n2_1/b_Cisco_n5k_SAN_Switching_Config_513_N2_1/b_Cisco_n5k_nxos_sanswitching_config_guide_rel513_n1_1_chapter_01000.html
Walter.