The value of this object is an index number of a
snRtIpPortConfigTable row (i.e. snRtIpPortConfigPortIndex),
which is the selected row to copy all of its read-writable
data (i.e. snRtIpPortMtu and snRtIpPortEncap) to the rest
of the rows in snRtIpPortConfigTable.
Note: prior setting this object, all the intended data of
the given row of the table must be set. Otherwise, the
current data of the row will be used to set the entire ip
interface configuration table. The previous setting will
be overwritten by the new one.