In one embodiment, a device in a network sends a first multicast message to a plurality of destinations in the network. The first multicast message includes a first bitmap that identifies the destinations. The device receives one or more acknowledgements from a subset of the destinations. The device determines a retransmission bitmap that identifies those of the plurality of destinations that did not acknowledge the first multicast message, based on the received one or more acknowledgements. The device sends a retransmission multicast message to those of the plurality of destinations that did not acknowledge the first multicast message. The retransmission multicast message includes the retransmission bitmap.