The object identities the interface to which the
upstream channel thresholds applies:
1. If '0', then the policy applies to all upstream
channels being monitored.
2. If the corresponding ifType is 'docsCableMacLayer',
then the policy applies to all upstream channels
being carried by the physical interface.
3. If the corresponding ifType is 'docsCableUpstream',
then the policy applies to that upstream channel.