A ratio used in allocating the allocatable bandwidth among the
various Service classes. This value is the amount of the overall
allocatable bw that can be allocated to ABR. The values are 1-255.
For a more detailed description of value useage see
sfcsBwPortPoolLimitsBwConstant. Total of all service classes for a
given direction should not exceed 256. (If it has never been set,
the value will be -1.)