This object applies only to virtual ports and specifies the unique
data link circuit or channel identifier assigned to this virtual port.
For example, if this virtual port is attached to a Frame Relay network,
this object would specify the DLCI associated with this virtual port.
The Parent of this virtual port is identified by a3ComPortPath (which
also identifies the physical path that this virtual port is associated
with).
This object must be specified when adding a new virtual port.