-> show /SYS/MB fru_part_number /SYS/MB Properties: fru_part_number = 7014379 ->
For example, 7014379.
If the part number is greater than 7057249, the management controller is the newer type, and you cannot downgrade to 2.1.6 or lower.
If the part number is less than or equal to 7057249, the management controller is the older type, and you can downgrade to 2.1.6 or lower.
For this example, the part number is less than 7057249, and it is possible to downgrade to firmware 2.1.6 or lower.