Patent ID: 7079544

Claim:
A packet transfer device that interworks an MPLS network which uses multiprotocol label switching (MPLS) network which uses a MPLS protocol, and a network that does not use said MPLS protocol, wherein: in said MPLS network, packet switching is performed by the MPLS header which is added before a header of the layer corresponding to layer 3 of the Open System Interconnection (OSI) model, and in a network which does not use said MPLS protocol, packet switching is performed by a header of the layer corresponding to layer 2 of the OSI model, which is different from said MPLS header and is added before said layer 3 header, wherein said packet transfer device comprises: a first physical port which receives a packet that is transmitted from the network which does not use said MPLS protocol, a second physical port for connecting with said MPLS network, a memory that stores header transformation information that shows correspondence between a pair of information in said layer 2 header and information in said layer 3 header in correspondance with information in said MPLS header, and a processor that searches said header transformation information and transforms said layer 2 header contained in a packet received from said first physical port to said MPLS header corresponding to said layer 2 header.