Method of transferring multicast data, updating method of multicast tree, system and device thereof

A method for updating a multicast tree, comprising:

• receiving, by a first multicast node, a data packet sent by a first Mobile Access Gateway (MAG);
• constructing a Join message for generating a multicast tree when it is determined that a multicast source handover instruction is carried in the data packet, and forwarding address information of a second MAG carried in the data packet via the Join message;
• updating, by a second multicast node which receives the Join message, a multicast routing according to the address information of the second MAG carried in the Join message;
• and
• continuing forwarding the Join message until the multicast node receives the Join message after the multicast node updates the multicast routing according to the address information of the second MAG.

A device for transmitting multicast data, comprising:

• a handover message receiving unit, adapted to receive a handover message sent by a multicast source before handover of the multicast source from a first Mobile Access Gateway (MAG), to which the multicast source is currently accessed, to a second MAG, wherein the handover message carries identifier information of the second MAG;
• a tunnel establishing unit, adapted to establish a bidirectional tunnel between the first MAG and the second MAG according to the identifier information of the second MAG carried in the handover message received by the handover message receiving unit;
• and
• a multicast data transmitting unit, adapted to multicast data from the multicast source, based on a determined post-handover multicast mode and the bidirectional tunnel established by the tunnel establishing unit, wherein the post-handover multicast mode is a multicast mode adopted by the multicast source after the handover to the second MAG.