Multicast Backbone is one of the key technologies for constructing high-speed broadbandnetworks. Many multimedia applications such as video conference systems or ccoperative office automation systems have been developed based on MBone. However

Multicast Commnunication of multimedia data on MBone brings about overload of the network

so that new algorithms and mechanisms are needed to control and manage the QoS （Quality of Service）of networks. This paper summarises the state of the art on MBone and QoS management.