3-Layer VPN and constructing method thereof

• US 20040037275A1
• Filed: 01/03/2003
• Published: 02/26/2004
• Est. Priority Date: 08/23/2002
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Dong, Weisi, Li, Bing
• Granted Patent: US 7,411,955 B2
• Time in Patent Office: Days
• US Class Current: 370/370
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

The present invention discloses a 3-layer Virtual Private Network (VPN) which comprises P devices and PE devices in the backbone network, a plurality of sites and CE devices in subscribers'"'"' VPNs, and Hierarchy of PE (HoPE) devices, said HoPE devices serve as edge routers in the backbone network and are connected to P devices in the backbone network as well as sites and CE devices in subscribers'"'"' VPNs; said HoPE devices comprise understratum PEs (UPEs), zero or more middle-level PEs (MPES) and superior PEs (SPEs) connected with each other, and all of said PEs (UPEs, MPEs, and SPEs) take different roles and deliver the function of a central PE. For the SPEs, the routing and forwarding performance should be relatively higher; while for UPEs, the performance may be lower. The architecture according to the present invention can enhance the expandability in hierarchical BGP/MPLS VPNs.

Claims

1. 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 a 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 thereof, 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, and carrying labels;

an interface or a sub a sub-interface connected said UPE and said SPE or different UPEs, among which the messages are forwarded by labels;

2. A 3-layer VPN of claim 1, wherein said HoPE further comprising serveral middle-level PEs (MPEs) between the UPE and the SPE;

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 a MPE has generated a default route for the VRF, an ILM being generated on MPE.

3. A method for constructing a 3-layer VPN, comprising:

deploying a HoPE device in a backbone network, and said HoPE device, as an edge router in the backbone network, connected to a P device in the backbone network and several sites and CE devices in a subscribers'"'"' VPN;

said HoPE comprising an understratum PE (UPE) and a superior PE (SPE) connected each other;

wherein the UPE maintaining the routes to the VPN sites connected directly to the UPE, allocating internal labels for routes to the VPN sites, and issuing labels to SPEs through VPN routes;

the SPE maintaining all routes in the VPN where the sites are connected via the UPE, and issuing a default VRF (VPN routing/forwarding instance) route or converged VRF route to the UPE, and carrying labels;

connecting said UPE and SPE via an interface or sub-interface, and forwarding the messages with labels among them.

4. A method for constructing the 3-layer VPN of claim 3, said HoPE further comprising several middle-level PEs (MPEs) between the UPE and SPE, said MPEs maintaining all routes in the VPN where the sites are connected via the UPE, issuing a default VRF (VPN routing/forwarding instance) route or converged route to the UPE, and replacing the labels carried by the default VRF route issued from SPE, and issuing them to the UPE;

if a MPE has generated the default route for the VRF, an ILM being generated on the MPEs.

5. A method for constructing the 3-layer VPN of claim 4, characterized in that a MP-BGP (Multi Protocol-Border Gateway Protocol) being used to exchange messages among said SPE, MPEs, and the UPE connected each other.

6. A method for constructing the 3-layer VPN of claim 4, wherein:

if a same operator manages said SPE, MPEs and UPE, said MP-BGP being a MP-IBGP (Multi Protocol-Internal Border Gateway Protocol);

if different operators manage said SPE, MPEs and UPE, said MP-BGP being a MP-EBGP (Multi Protocol-External Border Gateway Protocol).

7. A method for constructing the 3-layer VPN of claim 3, 4, 5 or 6, wherein:

in the HoPE, the SPE generating a global import route-target list to filter routes from other PEs connected to the SPE according to the collection of import route-target list of all VRF of the UPE.

8. A method for constructing the 3-layer VPN of claim 7, comprising steps:

dynamically generating said global import route-target list according to the information exchanged between the SPE and UPE, and the generating step further comprising;

the UPE issuing a ORF (Outbound Route Filter) information to the SPE connected to them through a route refresh information for the BGP, the ORF containing an expanded group list, which is the collection of the import route-target list of all VRFs of the UPE;

said SPE converging the extended group list of the UPE connected to the SPE to generate z global list.

9. A method for constructing the 3-layer VPN of claim 8, wherein:

in the HoPE, if the UPE is connected with several SPEs, all the SPEs issuing the default VRF route to said UPE, and the UPE selecting one from them as a preferred route or select several routes to implement load sharing;

when issuing VPN routes to the several SPEs, the UPE issuing all VPN routes to all SPE or partial of VPN routes to each SPE for sharing load.

10. A method for constructing the 3-layer VPN of claim 9, wherein:

in the HoPE, when two UPEs are connected directly, any one of said two UPEs issuing all its VPN routes to the another to enable Sites connected by said two UPES communicate directly.