In this paper, we focus on approaches in network dimensioning where it allocates bandwidths and attempts to provide a proportionally fair treatment of all the competing classes. We willshow that an achievement function can map different criteria onto a normalized scale subject to varous utilities. The achievement function can be coped with the Ordered Weighted Averaging method.Moreover, it may be interpreted as a measure of QoS on All-IP networks. Using the achievement function, one can find a Pareto optimal allocation of bandwidths on the network under the available budget, which provides the so-called proportional fairness to each class. Consequently, this results in the similar satisfaction level to every connection in all classes.