In this paper, the manufacturing blocking system (MBS) is studied from the Network Calculus (NetCal) perspective. By dominating an MBS by a window flow controller (WFC), we obtain service curves for systems with instantaneous and noninstantaneous acknowledgements. The explicit expression for the system service curve leads to the optimal allocation of the buffer sizes, which guarantees the ideal system service curve: that is, the service curve for the system with no restrictions on the sizes of in-between buffers. This allocation is more efficient than one based on guarantees of individual service curves. In addition, a method of simulation of NetCal systems is developed exploiting the duality between arrival curves and strict service curves. Simulation experiments are conducted to show the tightness of the theoretical bounds obtained using NetCal. c 2005 Elsevier B.V. All rights reserved.