A method comprising: receiving , by a protocol independent multicast, PIM, backup designated router, BDR, a request from a host device to join a multicast group associated with a source of multicast traffic; in response to the request, sending , by the PIM BDR, a PIM join message to a next hop between the PIM BDR and the source of multicast traffic, the PIM join message comprising attributes identifying a first address of the PIM BDR and indicating that the PIM join message is a backup PIM join from a backup designated router, wherein sending the PIM join message to the next hop comprises sending the PIM join message towards at least one of the source of multicast traffic and a merge point for an active multicast tree associated with the multicast group and a backup multicast tree associated with the multicast group; receiving , by the PIM BDR, from a PIM router located along a path between the PIM BDR and the source of multicast traffic, a first unicast message sent to the first address, the first unicast message identifying a second address associated with the PIM router; storing , by the PIM BDR, the second address associated with the PIM router and a route associated with the first unicast message; in response to a designated router migration triggering event, changing a first instance of a backup multicast tree state at the PIM BDR from blocking to forwarding, the backup multicast tree state being associated with the source of multicast traffic and the multicast group; and sending , by the PIM BDR to the PIM router, a second unicast message comprising an instruction to change a second instance of the backup multicast tree state at the PIM router from blocking to forwarding. receiving , by a protocol independent multicast, PIM, backup designated router, BDR, a request from a host device to join a multicast group associated with a source of multicast traffic; in response to the request, sending , by the PIM BDR, a PIM join message to a next hop between the PIM BDR and the source of multicast traffic, the PIM join message comprising attributes identifying a first address of the PIM BDR and indicating that the PIM join message is a backup PIM join from a backup designated router, wherein sending the PIM join message to the next hop comprises sending the PIM join message towards at least one of the source of multicast traffic and a merge point for an active multicast tree associated with the multicast group and a backup multicast tree associated with the multicast group; receiving , by the PIM BDR, from a PIM router located along a path between the PIM BDR and the source of multicast traffic, a first unicast message sent to the first address, the first unicast message identifying a second address associated with the PIM router; storing , by the PIM BDR, the second address associated with the PIM router and a route associated with the first unicast message; in response to a designated router migration triggering event, changing a first instance of a backup multicast tree state at the PIM BDR from blocking to forwarding, the backup multicast tree state being associated with the source of multicast traffic and the multicast group; and sending , by the PIM BDR to the PIM router, a second unicast message comprising an instruction to change a second instance of the backup multicast tree state at the PIM router from blocking to forwarding. <EOS>