Device and method for setting internet protocol (IP) multicast retransmission port in three-layer switchboard

The invention discloses a device and a method for setting an internet protocol (IP) multicast retransmission port in a three-layer switchboard. The method comprises that a multicast retransmission layer module receives multicast protocol message to then determine a virtual local area network (VLAN), a port number and a source IP address of the message, the VLAN, the port number and the source IP address of the message are saved in a next multicast skip list, and the message is retransmitted to a multicast protocol layer; corresponding VLAN identifications are determined after multicast retransmission table item setting instruments are received, and the corresponding port number is found out according to the VLAN identifications and the next skip IP address in the instruments; the VLAN identifications and the port number serve as interface message to be set in the corresponding multicast routing table item of a hardware retransmission layer; and a multicast protocol layer module judges that the multicast retransmission table item setting instruments need issuing and then increases the source IP address in the issued instruments to serve as the next skip IP address. By means of the device and the method, retransmission correcting to the port from IP multicast can be achieved, simultaneously complexity of the multicast protocol is reduced, and generality of multicast protocols in routes and switching equipment is improved.