The table is used to get free indices of tables to create
new entries, and next free priorities.
The algorithm for free indexes depends on table types:
Fcl table - first free index.
Fce table - first free index.
Service table - first free index.
Service priority - last used priority + priority-delta.
The priority-delta is used to supply QoS MIB user easy new priority
insert entry capabilities.
Values of these deltas depend on the MIB implementation.
The 'Get and Increment' approach is used in all cases.