Patent ID: 7411955

Claim:
A 3-layer VPN, comprising a P device (Provider Router) and a PE device (Provider Edge Router) in a backbone network, several sites and CE devices in a subscribers' VPN; the VPN further comprising a hierarchy of PE device (HoPE) as an edge router in the backbone network and connected to the P device in the backbone network and the several sites and CE devices in the VPNs; said HoPE comprising an understratum PE (UPE) and a superior PE (SPE) which are connected with each other; the UPE maintaining the routes to VPN sites connected directly thereto, and allocating internal labels for routes to the VPN sites, and issuing labels to the SPE through the VPN routes; the SPE maintaining all routes in the VPN where the sites are connected via the UPE, and issuing default VRF (VPN routing/forwarding instance) routes or converged VRF routes to UPE, with labels carried; one interface or sub-interface connecting said UPE and said SPE or connecting different UPEs, between which the messages are forwarded by labels; wherein said HoPE further comprises several middle-level PEs (MPEs) between the UPE and the SPE; and said MPEs maintaining all routes in the VPN where the sites are connected via the UPE, issuing default VRF (VPN routing/forwarding instance) routes or converged routes to the UPE, and replacing the labels carried by the default VRF routes issued from SPE, and issuing them to UPE; if an MPE has generated a default route for the VRF, an ILM being generated on the MPE.