A method for transmitting at least one data stream of a multimedia session through a distributed telecommunications network comprising at least one network core comprising a plurality of nodes (10, 12) interconnected by a plurality of links, each node (10, 12, 14) of said network having a routing module, said session being established between a first terminal and at least one second terminal outside the network core, and said network core also comprising at least two border modules (20, 20', 20"), making up points of access to said network core for the first and second terminals (1, 2), the method including the following steps: - determination, by said border modules (20, 20', 20"), of information relative to the routing topology and the status of the links (7, 16) of said network, necessary for the transmission of data streams of the session, - determination, by a border module addressed by the first terminal, of parameters of said session comprising a length of the session and flow constraints for the streams of said session in the network core, - selection, by said addressed border module, when said data streams must pass through the network core, of an input border module and an output border module (20") of said network core for said streams, as a function of said stream flow constraints and said predetermined session parameters, and said information relative to the routing topology and the status of the links (7, 16), - predetermination of a path, from said input border module to said output border module (20"), for all of said streams of the session, through said network core, as a function of said flow constraints of the streams and said information relative to the routing topology and the status of the links (7, 16), and as a function of optimization objectives for the network core, - establishment of the resources necessary to satisfy said flow constraints along said path and the optimization objectives, and definition of routing rules with routing modules situated along said path, and - transmission of said streams of the session only using said predetermined path, the method also comprising a step for compressing headers of the packets of the streams of the session, before they are transmitted in the network core, and a step for decompressing those headers, after they are transmitted in the network core. - determination, by said border modules (20, 20', 20"), of information relative to the routing topology and the status of the links (7, 16) of said network, necessary for the transmission of data streams of the session, - determination, by a border module addressed by the first terminal, of parameters of said session comprising a length of the session and flow constraints for the streams of said session in the network core, - selection, by said addressed border module, when said data streams must pass through the network core, of an input border module and an output border module (20") of said network core for said streams, as a function of said stream flow constraints and said predetermined session parameters, and said information relative to the routing topology and the status of the links (7, 16), - predetermination of a path, from said input border module to said output border module (20"), for all of said streams of the session, through said network core, as a function of said flow constraints of the streams and said information relative to the routing topology and the status of the links (7, 16), and as a function of optimization objectives for the network core, - establishment of the resources necessary to satisfy said flow constraints along said path and the optimization objectives, and definition of routing rules with routing modules situated along said path, and - transmission of said streams of the session only using said predetermined path, the method also comprising a step for compressing headers of the packets of the streams of the session, before they are transmitted in the network core, and a step for decompressing those headers, after they are transmitted in the network core.