Techniques reliably provide the switchover from a default MDT to the data MDT by using reliable signaling and reliable building of a data MDT. The message notifying of the pending switchover to the data MDT is reliably sent using signaling that is reliable. Also, the switchover from the default MDT to the data MDT does not happen until all egress routers have responded to the message. Egress routers join the data MDT if associated receivers are interested in receiving the multicast stream from a source. The router does not send another response upstream until all egress routers downstream from it respond to the message in the positive or the negative.