The value of this object is 1 which means invoking
Port STP Set-all command. The snPortStpPriority,
snPortStpPathCost, the read-write STP related
attributes of the first row of table will be used
to set the same attributes for all the ports in the
system.
Note: prior setting this object, all the intended
attributes of the given row of the table must be set.
Otherwise, the current data of the row will be used to
set the entire port-table. The previous setting will
be overwritten by the new one.