This attribute specifies the guaranteed number of multicast branches
that can be activated on this AtmIf, including those activated
beneath a Vpt.
The sum of minMulticastBranches across all AtmIfs of the Lp must
be less than or equal to the multicastBranchesCapacity attribute of
the Arc component of the Lp.
For CQC-based ATM cards, the value of the attribute can not
exceed 10752.
If this value is non zero, the Arc component must exist and have
multicastBranchesCapacity set to a value greater than or equal to
this attribute.