There exists large Leave latency (often on the order of several seconds)in current Internet group management mechanism. This will cause layered multicast congestion control in slow response to network congestion. We give a new concept of layer transfer,which can implement rapid congestion response in layered multicast. Layer transfer will move congested layer data from one group to another ,and the receivers will determine whether to re-subscribe the moved layer or not according to their current situations. Layer transfer has a key feature that it replaces slow Leave process by fast Join process ,so it doesn't require any change to IGMP protocol ,routers ,or other multicast routing protocol. The simulation results show the new method can improve layered multicast sessions' fairness towards TCP sessions.
