Resiliency in minimum cost tree-based VPLS architecture

• US 20070047556A1
• Filed: 08/29/2005
• Published: 03/01/2007
• Est. Priority Date: 08/29/2005
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Cuervo, Fernando, Raahemi, Bijan, Bou-Diab, Bashar
• Granted Patent: US 7,719,957 B2
• Time in Patent Office: Days
• US Class Current: 370/395.530
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• 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 45/16 Multipoint routing
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04L 45/484 using multiple routing trees
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

A system for providing resilient multimedia broadcasting services over a VPLS network is described. A network Management System (NMS) calculates disjoint minimum cost trees using the Steiner algorithm executed with extra steps to result in the disjoint trees. Destination PE routers in the VPLS network are connected to the disjoint trees so that they can be serviced by either tree in the case of a fault. Each of the disjoint trees is provisioned with enough bandwidth to carry all of the services provided by the VPLS network. Under normal operation, however, the services are distributed evenly over the trees. In the event of a fault, the services on the faulty tree are switched to the other tree using split horizon bridging. Each Steiner tree can also be realized using poin-to-multipoint LSPs which is fully protected by a precomputed point-to-mulltipoint LSP.

Claims

1. A method of providing broadcast services over a VPLS network having at least two source PE routers, each of which is connected to a respective head-end system for broadcasting services, and having a plurality of destination PE routers, each of which is connected to at least two core provider (P) routers in the VPLS network, the method comprising the steps:

a) calculating a plurality of Steiner trees, each such tree being sourced by a respective source PE router and including each destination PE router, the plurality of Steiner trees being disjoint from one another with respect to at least the core P routers in the VPLS network;

b) provisioning each of the Steiner trees with enough bandwidth to carry all of the broadcast services; and

c) broadcasting a portion of the broadcast services over each of the Steiner trees, whereby all of the broadcast services are broadcasted over the plurality of Steiner trees.

2. The method as defined in claim 1 wherein the broadcast services are distributed evenly over the trees.

3. The method as defined in claim 1 wherein the minimum-cost (Steiner) tree is realized using point-to-multipoint LSP.

4. The method as defined in claim 1 wherein, responsive to a fault in one of the trees, IGMP membership of services of the faulty tree is inserted in the head-end system of non-faulty tree(s) and CE routers of the faulty tree is attached to the non-faulty tree(s) using split horizon bridging.

5. The method as defined in claim 4 wherein bandwidth is freed-up on the faulty tree.

6. The method as defined in claim 1 wherein the broadcast services are digital multimedia services.

7. The method as defined in claim 6 wherein the multimedia services are digital TV services.

8. The method as defined in claim 6 wherein the multimedia services are video on demand services.

9. The method as defined in claim 1 wherein a Network Management system (NMS) is sued to provide the broadcast services.

10. The method as defined in claim 9 wherein the NMS pre-computes two Steiner trees such that bandwidth is reserved for each tree.

11. The method as defined in claim 10 wherein a load balancing mechanism is employed to distribute channels on both trees evenly.

12. A Network Management System (NMS) for providing broadcast services over a VPLS network having at least two source PE routers, each of which is connected to a respective head-end system for broadcasting services, and having a plurality of destination PE routers, each of which is connected to at least two core provider (P) routers in the VPLS network, the NMS comprising:

means for calculating a plurality of Steiner trees, each such tree being sourced by a respective source PE router and including each destination PE router, the plurality of Steiner trees being disjoint from one another with respect to at least the core P routers in the VPLS network;

means for provisioning each of the Steiner trees with enough bandwidth to carry all of the broadcast services; and

means for broadcasting a portion of the broadcast services over each of the Steiner trees, whereby all of the broadcast services are broadcasted over the plurality of Steiner trees.

13. The NMS as defined in claim 12 having means for provisioning each of the Steiner trees using point-to-multipont LSPs.

14. The NMS as defined in claim 12 wherein the bandwidth is distributed evenly between the Steiner trees.

15. The NMS as defined in claim 14 wherein in the event of a failure in one Steiner tree the services are provided over one or more of the other trees.

16. The NMS as defined in claim 15 wherein load balancing means are used to distribute services.

17. The NMS as defined in claim 15 wherein split horizon bridging is used to distribute services.

18. The NMS as defined in claim 12 wherein two Steiner trees are calculated, one a normal operating tree and the second a backup tree.