IP multicasting has naturally been considered the ideal technique to be used with multimedia communications. Unfortunately, current multicast protocols do not consider the dynamic membership. Therefore, we propose a time and distance-based multicast algorithm (TDBMA) for IPv6 mobile networks. The TDBMA is subject to time and distance. A foreign network is qualification to join the existing multicast tree only its value of time and distance is larger than a computed threshold. The experimental analyses are presented to characterize the performance of the proposed algorithm.