摘要 |
In an open flow network system, a packet to be subjected to multicast transmission is transmitted to a plurality of VLANs which are different. Specifically, a packet transfer processing unit determines, when receiving a packet, whether or not the packet is for the multicast transmission. In case of the multicast transmission, whether or not the packet has been completely transmitted to ports specified for destinations is checked. When not having completely transmitted, a packet header of a packet is rewritten, and the written packet is copied and transmitted to a destination port and a network processor (NP). Through the loop-back processing, whether or not the packet received from NP is for the multicast transmission is determined. In case of the multicast transmission, it is checked whether or not the packet has been completely transmitted to the ports specified for destination. When having not been completely transmitted, the packet is rewritten in the packet header and is copied and transmitted to the destination port and the NP. When having been completely transmitted, the packet is discarded and the processing is ended. |