Hi,
x440 doesn't support this feature.
If the doc doesn't clearly say it, this is something we'll have to correct.
From the EXOS 15.4.1 RN:
Supported Platforms
ā¢ BlackDiamond 8800 xl-series only switches
ā¢ BlackDiamond X8 series switches
ā¢ Summit X480, X460, X670, and X770 series switches
ā¢ E4G-400 and E4G-200 cell site routers