I understand the fault-tolerance with Bonding but if i need more bandwith for iSCSI ?

My OpenE has 6 NIC Gigabit (2 x Intel Dual Port and 2 from MotherBoard) if i want best performance what is the best ?

For Performance what is the best ?

A switch with 802.3 ad or using 1 NIC for each iSCSI volume ?