Patent ID: 7272146

Claim:
In an MPLS-VPN (MultiProtocol Label Switching-Virtual Private Network) system for providing VPN services by using MPLS, an interface identifying device comprising: a plurality of virtual routers, a first virtual router of the plurality of virtual routers capable of processing IP (Internet Protocol) packets received via a plurality of particular virtual interfaces that belong to a same VPN, the first virtual router capable of transmitting IP packets through the plurality of particular virtual interfaces; and an MPLS label operating device for processing label information for transferring a received IP packet over an MPLS-VPN service network, said MPLS label operating device including: a first-stage MPLS label operating section for stacking on the IP packet a first-stage MPLS label for transferring said IP packet over the MPLS-VPN service network; and a second-stage MPLS label operating section for stacking on the IP packet a second-stage MPLS label for identifying one of a plurality of virtual interfaces; wherein the MPLS label operating device is connected to receive IP packets transmitted by the first virtual router through each of the plurality of particular virtual interfaces; and wherein the second-stage MPLS label operating section is configured such that, when the MPLS label operating device receives a particular IP packet that has been transmitted by the first virtual router, the second-stage MPLS label operating section determines a particular second-stage MPLS label of a plurality of second-stage MPLS labels to stack onto the particular IP packet based on which one of the plurality of particular virtual interfaces the first virtual router used to transmit the particular IP packet.