A technique is provided for processing a data stream between a server and a client entity in a packet communication network. The data stream is composed of packets steered by a processing device. Upon the receipt of a first packet of the data stream, the processing device implements a phase of observing this data stream, in the course of which the packets of the data stream which are exchanged between the server and the client entity and which follow the first packet are transmitted. On detection of congestion associated with the data stream, the data stream is then rejected and the processing device does not transmit packets of the data stream which are exchanged between the server and the client entity and are received after detection of the congestion.