/* set src mac address */
si = vnet_get_sw_interface(vnm, tx_sw_if_index0);
hi = vnet_get_hw_interface (vnm, si->hw_if_index);
/* set src mac address */
si = vnet_get_sw_interface(vnm, tx_sw_if_index0);
hi = vnet_get_hw_interface (vnm, si->hw_if_index);