For the set operation: UBR_Cfg is set across all boards in the
chassis (that are operational and manageable).
For the get operation: UBR_Cfg setting is retrived from the
current chassis manager only (one slot only).
IF boards are introduced or re-introduced to the chassis their
UBR value will be 0. In order to insure a required UBR_Cfg value
the set operation should be proformed after slot insertions or
re-insertions are completed to the chassis.