A router for controlling multicast transmission in a low-power wireless network, the router comprising: - a trickle-based multicast protocol layer, MPL, interface adapted to create a multicast packet; and, - a Medium Access Control, MAC, layer interface comprising a MAC layer queue adapted to receive a plurality of multicast packets, the MAC layer interface being adapted to transmit, over the network, the multicast packets stored in the MAC layer queue in their order of arrival, the MAC layer interface further comprising a MAC retry mechanism associated with a backoff mechanism and adapted to retransmit unsuccessfully transmitted multicast packets; characterised in that the router further comprises: - a real-time layer, RTL, interface coupled to the MPL layer interface and the MAC layer interface, and adapted to: - disable the MAC layer queue, the MAC retry mechanism and the MAC backoff mechanism; - receive the multicast packet from the MPL layer interface; and, - either, - alter the multicast packet by adding a deadline by which said altered multicast packet is to be discarded by a router of the network where said deadline has already passed; or, - discard said multicast packet where said deadline has already passed; where said multicast packet has been altered, the RTL interface is further adapted to: - forward said altered multicast packet to the MAC layer interface when the latter is ready to transmit; and, - put said altered multicast packet on hold when the MAC layer is not ready to transmit; wherein the RTL interface is adapted to forward or put on hold said altered multicast packet based on said deadline. - a trickle-based multicast protocol layer, MPL, interface adapted to create a multicast packet; and, - a Medium Access Control, MAC, layer interface comprising a MAC layer queue adapted to receive a plurality of multicast packets, the MAC layer interface being adapted to transmit, over the network, the multicast packets stored in the MAC layer queue in their order of arrival, the MAC layer interface further comprising a MAC retry mechanism associated with a backoff mechanism and adapted to retransmit unsuccessfully transmitted multicast packets; - a real-time layer, RTL, interface coupled to the MPL layer interface and the MAC layer interface, and adapted to: - disable the MAC layer queue, the MAC retry mechanism and the MAC backoff mechanism; - receive the multicast packet from the MPL layer interface; and, - either, - alter the multicast packet by adding a deadline by which said altered multicast packet is to be discarded by a router of the network where said deadline has already passed; or, - discard said multicast packet where said deadline has already passed; - disable the MAC layer queue, the MAC retry mechanism and the MAC backoff mechanism; - receive the multicast packet from the MPL layer interface; and, - either, - alter the multicast packet by adding a deadline by which said altered multicast packet is to be discarded by a router of the network where said deadline has already passed; or, - discard said multicast packet where said deadline has already passed; - alter the multicast packet by adding a deadline by which said altered multicast packet is to be discarded by a router of the network where said deadline has already passed; or, - discard said multicast packet where said deadline has already passed; - forward said altered multicast packet to the MAC layer interface when the latter is ready to transmit; and, - put said altered multicast packet on hold when the MAC layer is not ready to transmit;