dmtAlDslNetworkProfile-MarginConfig-RaUpshiftMarginDown 1.3.6.1.4.1.529.23.10.1.1.52

Valid ONLY in rate-adapt-mode = DYNAMIC. In dB. If current down stream noise margin is above this parameter for more than ra-downshift-int-down sec, modem shall attemp to rate adapt (bitrate up).