Frame transfer method and frame transfer device

A frame transfer method in a network system which includes a starting node coupled to a terminal for transmitting a frame to the starting node via a local node, and a terminating node, wherein a transfer path is defined between the starting node and the terminating node through the network, the frame transfer method comprising the steps of:

• by the starting node, receiving the frame transferred from the local node;
• by the starting node, deciding a transfer path in the network to be used for transferring the received frame through the network according to transfer path selection information included in the received frame, the transfer path selection information specifying the transfer path in the network leading to a destination of the frame outside of the network,
• by the starting node, transmitting the received frame to a terminating node on the network of the transfer path in the network decided by the starting node;
• wherein the local node is connected between the terminal and the starting node;
• by the starting node, writing the transfer path selection information in the frame;
• by the starting node, transmitting, to the terminating node on the network, the transfer path selection information corresponding to a plurality of destination terminal addresses which correspond to a plurality of said destination of frames outside the network to which frames are to be transferred via the network, and destination selection information corresponding to the plurality of destination terminal addresses for transmission to the terminating node;
• by the terminating node, receiving the frame transmitted from the local node for receiving the frame through the starting node of the transfer path;
• by the terminating node, deciding an output line outside of the network to be used for transmitting the frame according to the output line information included in the received frame, the output line information specifying the output line outside of the network decided from a destination of the frame;
• by the terminating node, transmitting the received frame to the terminal of destination of the frame through the output line outside of the network decided by the step of deciding by the terminating node;
• and
• by the terminating node, transmitting, to the starting node, transfer path selection information corresponding to a plurality of destination terminal addresses which correspond to a plurality of said output line to which frames are to be transferred via the network, and output line selection information corresponding to the plurality of destination terminal addresses for transmission to the terminal.

A network system including a frame transfer device which is connected to a node for receiving a frame from a terminal and to a starting node of a transfer path in a network, the frame transfer device being further connected through the network to a plurality of terminating nodes of the transfer path in the network, and yet further to a terminal of destination of the frame,

• wherein the frame transfer device comprises:
• a frame transmission/reception unit for receiving the frame transferred by the node;
• and
• a header process unit for deciding a transfer path in the network to be used for transferring the received frame through the network according to transfer path selection information included in the received frame, the transfer path selection information specifying the transfer path in the network leading to a destination of the frame outside of the network;
• and for deciding an output line outside of the network to be used for transmitting the frame according to an output line selection information included in the received frame, the output line selection information specifying the output line outside of the network decided from a destination of the frame,
• wherein the frame transmission/reception unit transmits the received frame to a terminating node on the network of the transfer path in the network decided by the header process unit, and further to the terminal of destination of the frame through the output line outside of the network decided by the header process unit;
• the node is connected between the terminal and the frame transfer device;
• the transfer path selection information and the output line information are written in the frame by the node;
• the frame transmission/reception unit transmits, to the starting node on the network, transfer path selection information corresponding to a plurality of destination terminal addresses which correspond to a plurality of said destination of frames outside the network to which frames are to be transferred via the network, and which further correspond to a plurality of said outside line via which the frames are to be transferred from the network to said destination of frames outside the network;
• destination selection information corresponding to the plurality of destination terminal addresses for transmission to the terminating node;
• and output line selection information corresponding to the plurality of destination terminal addresses for transmission to the terminal;
• the network is a Multi-Protocol Label Switching (MPLS) network;
• and
• the frame transmission/reception unit transmits from outside the MPLS network to the MPLS network when transmitting the frame.