the packet switching system for transmitting and receiving a packet via a packet switching network 100 , which comprises a plurality of routing tables , each of which has been generated by a unique routing policy , stored in the routing apparatuses deployed at the border , at the origin or at the end of the respective routing domains , an identifier inserted in the packet to specify the routing tables , and an identifier changer to change a value of the identifier on the packet switching network 100 . the routing apparatus selects one of the routing tables according to the rti in the received packet and transfers the packet to a destination that is specified by the selected routing table .