Router device and frame transfer method using datalink layer frame switching

A method of frame transfer at a router device, comprising the steps of:

• (a) storing a correspondence of a datalink flow identifier for identifying each flow on a datalink layer and an address information of a next hop node to which frames of packets belonging to each flow are to be transferred next in a memory of the router device;
• (b) receiving a frame to be transferred by a datalink layer level switching, said frame having the datalink flow identifier for identifying a flow of a packet corresponding to said frame on the datalink layer, the datalink flow identifier being contained in a prescribed region of said frame corresponding to an upper layer protocol identification information region of a frame format for frames to be transferred via a network layer processing;
• and
• (c) transferring said frame received from a previous hop node belonging to one logical network by the step (a) to the next hop node belonging to another logical network, by obtaining the address information of the next hop node by referring to the correspondence stored by the memory using at least the datalink flow identifier contained in said prescribed region of said frame as a key, and by attaching the address information of the next hop node to said frame, without carrying out the network layer processing.