List of attributes for a single upstream channel. For
Docsis 2.0 CMTSs, an entry in this table exists for
each ifEntry with an ifType of docsCableUpstreamChannel (205).
For Docsis 1.x CM/CMTSs and Docsis 2.0 CMs, an entry in this table exists
for each ifEntry with an ifType of docsCableUpstreamInterface (129).