QoS alternate path for multicast

Current algorithms adopted by most multicast routing protocols only consider one or two QoS metrics, without regard to the capabilities of the path nor its current load. With the changes of the network topology and resources available, the receivers have no alternative if the default multicast tree can not meet application requirements. It is so important to reroute a constraint multicast tree from receivers in advance. CAPM algorithm that aims to resolve this problem can find feasible alternate path according to the receiver's needs, its validity and performance are illustrated in large and heavy load network.