Call setup control apparatus in ATM switch

A call setup control apparatus, equipped In an ATM switch with a plurality of buffers for respective priority classes of calls, for providing priority control of calls of a plurality of types with different quality of service requirements, said apparatus comprising:

• a first calculation means for calculating an objective value of cell loss ratio PB(u) of a buffer Bu in priority class u which is equal to or lower than a priority class k (u=k to K), based upon parameters of an average cell rate R(k,j), an objective value of cell loss ratio Q(k,j), and the number of calls N(k,j) for calls of each type j (j=1 to Jk) in each class k (=1 to K), with considering a cell rate of calls in priority class which is higher than the class k (class 1 to k−1), when a fresh call is arrived;
• means for obtaining a bandwidth α(k,u,j) required for calls of type j in class k in the buffer Bu to make a cell loss ratio in the buffer Bu to be equal to or less than the objective value PB(u);
• a second calculation means for calculating a required bandwidth C(u) for the buffer Bu, based upon the obtained bandwidth α(k,u,j);
• and
• means for judging whether the fresh call is acceptable or not by comparing the calculated bandwidth C(u) with a link capacity CP.