A method of estimating traffic values or intervals in a communications network, the network comprising a plurality of nodes being interconnected by links, the method comprising the steps of (a) obtaining traffic data through the nodes or links as input data; (b) obtaining network data relating to the network topology and network behaviour; and (c) estimating the effect of a modification of the communications network and/or its behaviour be calculating traffic information between a selected first and a selected second node of the network using the input data.