Question about updating MAC address for ethernet adaptor

Hi all,

I have a question about updating MAC address for ethernet adaptor.

I am developing a driver for ethernet adaptor.
My driver is getting matched and loaded for the ethernet adaptor, I could
transfer data through my driver.

I am using the following command to update the ethernet (MAC) address:
      sudo ifconfig en0 ether aa:bb:cc:dd:ee:ff

But, when I try to change the ethernet address, it's not getting updated.
ifconfig does not even report any error.

I overridden IONetworkController::
setHardwareAddress in my driver and added code to update the ethernet
address to driver variable. I return IOReturnSuccess from this.

I observed that the overridden setHardwareAddress is not getting called at
all.

Could you please suggest what I am missing in this.

Thanks in advance!!