Methods and systems for providing MPLS-based layer-2 virtual private network services

• US 20040151181A1
• Filed: 02/04/2003
• Published: 08/05/2004
• Est. Priority Date: 02/04/2003
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Chu, Thomas P., Richman, Steven H., Zhao, ZhengXue, Magee, Francis R.
• Granted Patent: US 7,872,991 B2
• Time in Patent Office: Days
• US Class Current: 370/392
• CPC Class Codes: H04L 12/462 LAN interconnection over a bridge based backbone
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 2212/00 Encapsulation of packets
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/742 Route cache; Operation thereof
• CPC Class Codes: H04L 47/10 Flow control; Congestion control

Abstract

Methods and systems for forwarding packets over Label Switched Paths (LSPs) in a Virtual Private Network (VPN) are implemented within a Layer-2 architecture. A system includes a number of multi-purpose nodes connected by a number of multi-protocol label switching (MPLS) LSP links. Each multi-purpose node contains at least one bridging module (BM) that runs an extension of a bridging protocol (BP) contained in the IEEE 802.1d standard. The BP is used to establish MPSL LSPs between the BMs. The BP then generates a spanning tree using a spanning tree program to establish an optimal number of active LSPs. The remaining LSPs are then set to “inactive.” The BM de-allocates the resources assigned to inactive LSPs and makes the resources available to other active LSPs.

Claims

1. A processing unit for forwarding data packets over a Label Switched Path (LSP) comprising:

at least one bridging module (BM) operable to;

generate a spanning tree for at least one Virtual Private Network (VPN) to indicate an optimal set of LSPs;

determine active LSPs and inactive LSPs within the VPN; and

reallocate resources associated with inactive LSPs for forwarding data packets.

2. The processing unit of claim 1 further operable to receive packets from a subscriber, wherein the packets are based on a Layer-2 address.

3. The processing unit of claim 1 further operable to:

generate a spanning tree for the VPN to indicate an optimal set of active LSPs for transferring data packets between a plurality of BMs.

4. The processing unit of claim 3 further operable to generate the spanning tree by:

determining a root BM for the VPN;

determining a designated BM and a non-designated BM for pairs of BMs connected by an active LSP; and

determining a optimal number of active LSPs required to provide full network connectivity.

5. The processing unit of claim 4 further operable to:

determine whether an LSP connection is active between two BMs;

for the active LSPs, performing a first sequence, comprising;

sending a control message from the non-designated BM to the designated BM;

setting a resource flag in the control message to a first value at the non-designated BM; and

setting a flag at the designated BM to a first value indicating that the designated BM can receive information packets from the non-designated BM on the LSP connection; and

for the inactive LSPs, performing a second sequence, comprising;

setting the resource flag in the control message to a second value at the non-designated BM; and

setting the flag at the designated BM to a second value indicating that the designated BM cannot receive information packets from the non-designated BM on the LSP connection.

6. The processing unit of claim 5 further operable to:

reallocate bandwidth associated with the LSP between the non-designated BM and the designated BM; and

maintain a control channel for transmitting the control messages.

7. The processing unit of claim 4 further operable to determine a root BM by:

determining an administrative priority field that specifies the priority for the BM to become the root BM in the VPN; and

selecting the BM that has the highest priority.

8. The processing unit of claim 7, wherein the administrative priority field comprises:

a plurality of administrative preference parameters used to identify the preference of the BM in becoming a root BM in the VPN; and

a lock key parameter associated with at least one administrative preference parameter, wherein the lock key parameter is used to maintain the BM as the root BM.

9. The processing unit of claim 8, wherein the administrative preference parameter is selected from a group consisting of a geographic preference parameter, packet processing load parameter, a bandwidth availability parameter, and a load balancing parameter.

10. The processing unit of claim 4 further operable to:

determine bandwidth associated with the LSPs in the VPN;

sum the inverse of the bandwidth associated with the LSPs from the BM to the root BM.

11. The processing unit of claim 4 further operable to:

determine a total number of hops for the LSP in the VPN; and

calculate a hop count by summing hops from the BM to the root BM.

12. The processing unit of claim 3 further operable to generate the spanning tree by setting the LSPs between a root BM and non-root BMs as active.

13. The processing unit of claim 2 further comprising at least one interface operable to connect a Multi-Protocol Label Switching (MPLS) node to other MPLS nodes.

14. The processing unit of claim 13 wherein the interface is selected from a list consisting substantially of a physical interface, a MPLS-LPS, and an Internet Protocol Security (IPSec) interface.

15. The processing unit of claim 3, wherein the data packet is encapsulated by an outer MPLS label and an inner MPLS label, wherein the outer MPLS label identifies a node and the inner MPLS label identifies a VPN.

16. A method for forwarding data packets over a Label Switched Path (LSP) comprising:

generating a spanning tree for at least one Virtual Private Network (VPN) to indicate an optimal set of LSPs;

determining active LSPs and inactive LSPs within the VPN; and

reallocating resources associated with inactive LSPs for forwarding data packets.

17. The method of claim 16 further comprising receiving packets from a subscriber, wherein the packets are based on a Layer-2 address.

18. The method of claim 16 further comprising generating a spanning tree for the VPN to indicate the optimal set of active LSPs for transferring a data packet between a plurality of BMs.

19. The method of claim 18 further comprising:

determining a root BM for the VPN;

determining a designated BM and a non-designated BM for pairs of BMs connected by an active LSP; and

determining an optimal number of active LSPs required to provide full network connectivity.

20. The method of claim 19 further comprising:

determining whether an LSP connection is active between two BMs;

for the active LSPs, performing a first sequence, comprising;

sending a control message from the non-designated BM to the designated BM;

setting a resource flag in the control message to a first value at the non-designated BM;

setting a glad at the designated BM to a first value indicating that the designated BM can receive information packets from the non-designated BM on the LSP connection; and

for the inactive LSPs, performing a second sequence, comprising;

setting the resource flag in the control message to a second value at the non-designated BM; and

setting the flag at the designated BM to a second value indicating that the designated BM cannot receive information packets from the non-designated BM on the LSP connection.

21. The method of claim 20 further comprising:

reallocating bandwidth associated with the LSP between the non-designated BM and the designated BM; and

maintaining a control channel for transmitting the control messages.

22. The method of claim 19, wherein determining the root BM comprises:

determining an administrative priority field that specifies the priority for the BM to become the root BM in the VPN; and

selecting the BM that has the highest priority.

23. The method of claim 22, wherein the administrative priority field comprises:

a plurality of administrative preference parameters used to identity the preference of the BM in becoming a root BM in the VPN; and

a lock key parameter associated with at least one administrative preference parameter, wherein the lock key parameter is used to maintain the BM as the root BM.

24. The method of claim 23, wherein the administrative preference parameter is selected from a group consisting of a geographic preference parameter, packet processing loan parameter, a bandwidth availability parameter, and a load balancing parameter.

25. The method of claim 19, wherein generating the spanning tree comprises:

determining bandwidth associated with the LSPs in the VPN; and

summing the inverse of the bandwidth associated with the LSPs from the BM to the root BM.

26. The method as in claim 19, wherein generating the spanning tree comprises:

determining a total number of hops for the LSP in the VPN; and

calculating a hop count by summing hops from the BM to the root BM.

27. The method of claim 18, wherein generating the spanning tree comprises setting the LSPs between the root BM and non-root BMs as active.

28. The method of claim 17, further comprising connecting a Multi-Protocol Label Switching (MPLS) node to other MPLS nodes.

29. The method of claim 18, wherein the data packet is encapsulated by an outer MPLS label and an inner MPLS label, and wherein the outer MPLS label identifies a node and the inner MPLS label identifies a VPN.