A method for cross-stratum path computation in a network, comprising: a) receiving, at an application layer traffic optimization (ALTO) server at a network layer of a network, a request from an ALTO client at an application layer of said network to obtain a network cost map for assisting a connection of an end-user; b) computing, by a routing and/or a path computation engine of said network layer, network cost information concerning a plurality of Provider-defined Identifiers (PIDs) stored in said ALTO server; and c) transmitting, from the ALTO server, upon receiving said computed network cost information from said routing and/or path computation engine, the obtained network cost map to said ALTO client, the latter deciding through which of said plurality of PIDs to perform said connection with said end-user, d) receiving, by a provisioning server at said network layer, a request from a provisioning client of said application layer to compute a path for setting up a connection between said decided plurality of PIDs, wherein said method is characterized in that in said step b) comprises using a request controller at said network layer and queried by said ALTO server adapting the computed network cost information to an ALTO cost information, said request controller further sending said adapted ALTO cost information to the ALTO server and also storing it in a request database, and in said step d) comprises said provisioning server further transmitting said request to a provisioning controller, and the method further comprises: e) mapping, by said provisioning controller, said received request from the provisioning server into network addresses using ALTO identifiers; f) querying, by said provisioning controller, said routing and/or path computation engine for computing said path according to said network addresses; and g) comparing, by the provisioning controller, upon receiving said computed path from the routing and/or path computation engine, a network cost of the computed path with said cost information stored in said request database, wherein if said stored cost information being equal or higher than said network cost of the computed path said connection setting up being allowed or alternatively if said stored cost information being lower than said network cost of the computed path the connection setting up being rejected. a) receiving, at an application layer traffic optimization (ALTO) server at a network layer of a network, a request from an ALTO client at an application layer of said network to obtain a network cost map for assisting a connection of an end-user; b) computing, by a routing and/or a path computation engine of said network layer, network cost information concerning a plurality of Provider-defined Identifiers (PIDs) stored in said ALTO server; and c) transmitting, from the ALTO server, upon receiving said computed network cost information from said routing and/or path computation engine, the obtained network cost map to said ALTO client, the latter deciding through which of said plurality of PIDs to perform said connection with said end-user, d) receiving, by a provisioning server at said network layer, a request from a provisioning client of said application layer to compute a path for setting up a connection between said decided plurality of PIDs, e) mapping, by said provisioning controller, said received request from the provisioning server into network addresses using ALTO identifiers; f) querying, by said provisioning controller, said routing and/or path computation engine for computing said path according to said network addresses; and g) comparing, by the provisioning controller, upon receiving said computed path from the routing and/or path computation engine, a network cost of the computed path with said cost information stored in said request database, wherein if said stored cost information being equal or higher than said network cost of the computed path said connection setting up being allowed or alternatively if said stored cost information being lower than said network cost of the computed path the connection setting up being rejected.