Transfer device and communication network

Abstract

Provided is a transfer device () that includes a plurality of ports to and from each of which a layer-2 frame is input and output; a frame identification unit () that identifies whether or not the frame has been encrypted; an address filter unit () that decides one of the plurality of ports from which the frame is to be output; an encryption necessity determination unit () that has an encryption necessity determination table depending on destination information and priority information which are included in each frame, and a decryption necessity determination table depending on the destination information included in each frame, and when the frame has not been encrypted, determines whether or not encryption is necessary for the frame based on the encryption necessity determination table, and when the frame has been encrypted, determines whether or not decryption is necessary for the frame based on the decryption necessity determination table; an encryption decryption processing unit () that encrypts the frame for which it has been determined that encryption is necessary and decrypts the frame for which it has been determined that decryption is necessary; and a switching processing unit () that outputs the frame to one of the ports. Thus, the transfer device can realize both encrypted communication and plaintext communication.