Methods and apparatus for minimizing duplicate traffic during point to multipoint tree switching in a network

• US 20080031130A1
• Filed: 08/01/2006
• Published: 02/07/2008
• Est. Priority Date: 08/01/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Raj, Alex E., Thomas, Robert H.
• Granted Patent: US 7,899,049 B2
• Time in Patent Office: Days
• US Class Current: 370/225
• 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 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• 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 45/502 Frame based

Abstract

A method, apparatus and computer program product for minimizing or preventing duplicate traffic during point to multipoint tree switching in a network. In its operation, embodiments disclosed herein utilize control plane trigger mechanisms to handle the receipt of duplicate traffic by network entities after the occurrence of a network failure event. Generally, the control plane trigger mechanism prevents a network entity from processing multicast traffic from both old and new upstream data paths resulting from typical network convergence procedures. The methods and apparatus describe herein apply to standard rerouting procedures as well as fast rerouting procedures for multicast traffic in a network.

Claims

1. A method for minimizing duplicate traffic during point to multipoint (P2MP) tree switching in a network including a P2MP tree with a source node, the method comprising:

transmitting multicast data traffic from a first router over a primary network path to a second router, wherein the network path supports multicast label switching of multicast data traffic; and

in response to detecting a failure in the network, initiating a multicast rerouting procedure, the multicast rerouting procedure comprising;

transmitting a new switching label via a secondary network path to an upstream router, the secondary network path including at least one upstream node;

and, upon receiving an acknowledgement notification from the upstream router via the secondary network path, configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path.

2. A method as in claim 1 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

initiating a multicast rerouting procedure by implementing a reverse path forwarding procedure.

3. A method as in claim 1 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

determining whether the upstream router is receiving multicast data traffic, and when the upstream router is receiving multicast data traffic;

adding the new switching label to a routing table at the upstream node, and

transmitting the acknowledgement notification to the second router via the secondary network path.

4. A method as in claim 1 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

determining whether the upstream router is receiving multicast data traffic, and when the upstream router is not receiving multicast data traffic, repeating;

transmitting a respective switching label to a next upstream router via the secondary network path until the upstream router is receiving multicast data traffic; and

propagating the acknowledgement notification from the upstream router receiving multicast data traffic to the second router via the secondary network path.

5. A method as in claim 1 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

determining whether the upstream router is the source node of the P2MP tree, and when the upstream router is not the source node of the P2MP tree, repeating;

transmitting a respective switching label to a next upstream router via the secondary network path until the upstream router is the source node of the P2MP tree; and

propagating the acknowledgement notification from the source node of the P2MP tree to the second router via the secondary network path.

6. A method as in claim 1 wherein the configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path comprises:

removing, from the second router, a primary switching label that the second router normally uses for receiving multicast data traffic via the primary network path;

receiving, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.

7. A method as in claim 1 further comprising:

configuring the network to include at least one backup path between the first router and the second router, the backup path supporting multicast label switching of multicast data traffic;

in response to detecting the failure in the network, initiating transmission of the multicast data traffic over the at least one backup path between the first router and the second router in lieu of transmitting the multicast data traffic over the primary network path; and

upon receiving an acknowledgement notification from the upstream router via the secondary network path, configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path.

8. A method as in claim 7 wherein the configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path comprises:

removing, from the second router, a backup path switching label that the second router normally uses for receiving multicast data traffic via the at least one backup path;

receiving, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.

9. A computer readable medium having computer readable code thereon for providing a method for minimizing duplicate traffic during point to multipoint (P2MP) tree switching in a network including a P2MP tree with a source node, the medium comprising:

instructions operable on a processor to transmit multicast data traffic from a first router over a primary network path to a second router, wherein the network path supports multicast label switching of multicast data traffic;

in response to detecting a failure in the network, instructions operable on a processor to initiate a multicast rerouting procedure, the multicast rerouting procedure comprising;

instructions operable on a processor to transmit a new switching label via a secondary network path to an upstream router, the secondary network path including at least one upstream node; and

upon receiving an acknowledgement notification from the upstream router via the secondary network path, instructions operable on a processor to configure the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path.

10. A computer readable medium as in claim 9 wherein the instructions operable on a processor to initiate a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

instructions operable on a processor to initiate a multicast rerouting procedure by implementing a reverse path forwarding procedure.

11. A computer readable medium as in claim 9 wherein the instructions operable on a processor to initiate a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is receiving multicast data traffic, instructions operable on a processor to add the new switching label to a routing table at the upstream node; and

instructions operable on a processor to transmit the acknowledgement notification to the second router via the secondary network path.

12. A computer readable medium as in claim 9 wherein the instructions operable on a processor to initiate a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is not receiving multicast data traffic, repeating;

instructions operable on a processor to transmit a respective switching label to a next upstream router via the secondary network path;

instructions operable on a processor to propagate the acknowledgement notification from the upstream router receiving multicast data traffic to the second router via the secondary network path.

13. A computer readable medium as in claim 9 wherein the instructions operable on a processor to initiate a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is not the source node of the P2MP tree, repeating;

instructions operable on a processor to transmit a respective switching label to a next upstream router via the secondary network path;

instructions operable on a processor to propagate the acknowledgement notification from the source node of the P2MP tree to the second router via the secondary network path.

14. A computer readable medium as in claim 9 wherein the instructions operable on a processor to configure the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path comprises:

instructions operable on a processor to remove, from the second router, a primary switching label that the second router normally uses for receiving multicast data traffic via the primary network path;

instructions operable on a processor to receive, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.

15. A computer readable medium as in claim 9 further comprising:

instructions operable on a processor to configure the network to include at least one backup path between the first router and the second router, the backup path supporting multicast label switching of multicast data traffic;

in response to detecting the failure in the network, instructions operable on a processor to initiate transmission of the multicast data traffic over the at least one backup path between the first router and the second router in lieu of transmitting the multicast data traffic over the primary network path; and

upon receiving an acknowledgement notification from the upstream router via the secondary network path, instructions operable on a processor to configure the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path.

16. A computer readable medium as in claim 15 wherein the instructions operable on a processor to configure the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path comprises:

instructions operable on a processor to remove, from the second router, a backup path switching label that the second router normally uses for receiving multicast data traffic via the at least one backup path;

instructions operable on a processor to receive, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.

17. A network device comprising:

a memory;

a processor;

a communications interface;

an interconnection mechanism coupling the memory, the processor and the communications interface; and

wherein the memory is encoded with a network manager application that when performed on the processor, provides an network manager process for minimizing duplicate traffic during point to multipoint (P2MP) tree switching in a network including a P2MP tree with a source node, the network manager process causing the network device to be capable of performing the operations of;

transmitting multicast data traffic from a first router over a primary network path to a second router, wherein the network path supports multicast label switching of multicast data traffic;

in response to detecting a failure in the network, initiating a multicast rerouting procedure, the multicast rerouting procedure comprising;

transmitting a new switching label via a secondary network path to an upstream router, the secondary network path including at least one upstream node; and

upon receiving an acknowledgement notification from the upstream router via the secondary network path, configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path.

18. A network device as in claim 17 wherien the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

initiating a multicast rerouting procedure by implementing a reverse path forwarding procedure.

19. A network device as in claim 17 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is receiving multicast data traffic, adding the new switching label to a routing table at the upstream node; and

transmitting the acknowledgement notification to the second router via the secondary network path.

20. A network device as in claim 17 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is not receiving multicast data traffic, repeating;

transmitting a respective switching label to a next upstream router via the secondary network path;

propagating the acknowledgement notification from the upstream router receiving multicast data traffic to the second router via the secondary network path.

21. A network device as in claim 17 wherein the initiating a multicast rerouting procedure by transmitting a new switching label via a secondary network path to an upstream router comprises:

if the upstream router is not the source node of the P2MP tree, repeating;

transmitting a respective switching label to a next upstream router via the secondary network path;

propagating the acknowledgement notification from the source node of the P2MP tree to the second router via the secondary network path.

22. A network device as in claim 17 wherein the configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the primary network path comprises:

removing, from the second router, a primary switching label that the second router normally uses for receiving multicast data traffic via the primary network path;

receiving, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.

23. A network device as in claim 17 further comprising:

configuring the network to include at least one backup path between the first router and the second router, the backup path supporting multicast label switching of multicast data traffic;

in response to detecting the failure in the network, initiating transmission of the multicast data traffic over the at least one backup path between the first router and the second router in lieu of transmitting the multicast data traffic over the primary network path; and

upon receiving an acknowledgement notification from the upstream router via the secondary network path, configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path.

24. A network device as in claim 23 wherein the configuring the second router to receive multicast data traffic from the secondary network path in lieu of receiving multicast data traffic from the at least one backup path comprises:

removing, from the second router, a backup path switching label that the second router normally uses for receiving multicast data traffic via the at least one backup path;

receiving, at the second router, multicast data traffic in accordance with the new switching label used for the secondary network path.