Estimating/calculating traffic values, estimating the effect of/and modifying the network

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 said nodes and/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 said communications network and/or its behaviour by calculating traffic information between a selected first and a selected second node of said network using said input data. Other embodiments include a method of calculating traffic values comprising (a) and calculating a cumulative traffic flow, and a method of modifying a communications network comprising (a), (b) and automatically selecting promising candidates for a network modification.