A packet forwarding apparatus (L2SW) having a frame segmentation function of converting a extended Ethernet frame such as a MAC-in-MAC frame into a plurality of fragment frames when a payload length of the received frame exceeds a standard MTU size communicable in an Ethernet network to be a forwarding destination, by segmenting the received frame into a plurality of data blocks having a size not longer than the MTU size, and a frame assembling function of restoring an original extended frame from a series of fragment frames received from the Ethernet network.