The lower bound for the bandwidth of this upstream channel.
The bandwidth specified by docsIfUpChannelWidth is used as
the upper bound of the upstream channel. The two objects,
docsIfUpChannelWidth and cdxIfUpChannelWidth, in
conjunction, define the upstream channel width range to be
used for the automated spectrum management.
This object returns 0 if the channel width is undefined
or unknown.
For those upstreams in the linecards which do not have the
automated spectrum management feature, this channel width
is undefined and always has value 0.