An I/O board of a VXLAN switch receives a multicast data packet from a VLAN, and sends the multicast data packet to the fabric board of the VXLAN switch when at least one multicast group member port corresponding to the multicast data packet is a first virtual port. The fabric board determines that layer 3 multicast forwarding is to be performed by the fabric board. When a multicast group member port corresponding to the multicast data packet is a VXLAN tunnel port, the fabric board modifies a source MAC address of the multicast data packet, and sends the modified multicast data packet to an I/O board corresponding to the multicast group member port on the VXLAN switch. The I/O board corresponding to the multicast group member port adds a VXLAN encapsulation to the multicast data packet and forwards the multicast data packet having the VXLAN encapsulation to a VXLAN.