Rate increase factor (RIF) controls the amount by which the cell Tx rate
may increase upon receipt of an RM (Resource Management) cell.
The value is a power of 2 from 1/32768 to 1.
Legal values are 0-15 (0==1, 15==1/32768).
The default is 4 (2**-4==1/16) as specified by af-tm-0056.000.
Note:
May not be supported on all ATM-based platforms and/or service categories.