A method for requesting subscription to a data stream distributed in a multicast group. The group includes sources including a server, a first client and a second client, the sources being interconnected via an electronic communications network. The multicast group is identified by an address. A stream transmitted to the multicast group address by a first source is received by a second source if the second source is already subscribed to the first source. The first client is subscribed to the server. The method includes the first client performing acts of: receiving from the server at least one management message including at least one quality parameter relating to the stream transmitted to the address of the multicast group by the second client; making a decision to subscribe to the second client, according to a criterion dependent on the at least one quality parameter received; and, in the case of a positive decision, transmitting a subscription request message to the second client.