It is an efficient way for a mobilehost to obtain multicast service via a local multicast router on thevisited network. However, there is a possibility for a temporarydisruption of multicast service due to the join latency and other issuesin handoff procedure. This paper proposes a scheme to solve such aproblem. A smooth handoff mechanism is introduced to avoid unnecessarydata loss. Besides, any mobility agent capable of multicast can beappointed to provide service to mobile hosts, which makes it possible todeploy the protocol widely. Discrete-event simulations were conducted tosurvey the performance of the proposed scheme. The simulation resultsshow that the scheme has better performance than the comparedapproaches.