The method involves generating a matrix (M) based on the physical network, in which the columns and rows indicate the different nodes and the components (M[a,b]) the one or more transmission parameters between the nodes. The matrix (M) is coupled to provide a replica (M1) of the network. The matrix and its replica are converted to form a further matrix (M2) in accordance with a conversion function (F), which is indicative of random matrices (X,Y,Z). The network is an ATM or one which corresponds to it. The transmission parameters refer to one or more of the parameters defined for such a network, which may include the sustainable cell rate, the peak cell rate, the minimum cell rate or the maximum burst size.