ACKNOWLEDGEMENT-BASED REROUTING OF MULTICAST TRAFFIC

• US 20120188909A1
• Filed: 03/26/2012
• Published: 07/26/2012
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Arjen Boers, Dino Farinacci, Ijsbrand Wijnands, Stefano Previdi
• Original Assignee: Arjen Boers, Dino Farinacci, Ijsbrand Wijnands, Stefano Previdi
• Inventors: Previdi, Stefano, Farinacci, Dino, Wijnands, Ijsbrand, Boers, Arjen
• Granted Patent: US 8,879,429 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1877 Measures taken prior to transmission
• 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

Abstract

Various techniques for exchanging control messages in order to gracefully reroute multicast traffic are disclosed. For example, one method involves sending a join message for a multicast group towards a root of a new multicast tree and forwarding multicast traffic, addressed to the multicast group, on a current multicast tree until an acknowledgment corresponding to the join message is received. The new multicast tree can be identified in response to detection of a topology change within the network. Until the acknowledgment is received, multicast traffic that is received via the new multicast tree can be dropped.

Claims

1. A method comprising:

receiving a join message specifying a multicast group, wherein the join message is sent by a first network device, and

the join message requests acknowledgment;

in response to the receiving the join message,

determining whether a multicast tree corresponding to the multicast group already exists; and

sending an acknowledgment message to the first network device, in response to a determination that the multicast tree already exists.

2. The method of claim 1, further comprising:

establishing the multicast tree, without sending the acknowledgment message to the first network device, in response to a determination that the multicast tree does not already exist.

3. The method of claim 2, further comprising:

forwarding the join message to another network device toward a root of the multicast tree, in response to the determination that the multicast tree does not already exist.

4. The method of claim 2, wherein the establishing the multicast tree further comprises:

creating multicast state information associated with the multicast group, wherein the multicast state information identifies the multicast tree.

5. The method of claim 4, wherein the creating the multicast state information further comprises:

identifying an outgoing interface leading to the first network device in the multicast state information.

6. The method of claim 1, further comprising:

updating multicast state information associated with the multicast group, in response to the determination that the multicast tree already exists, wherein

the multicast state information is updated with an outgoing interface leading to the first network device.

7. The method of claim 1, wherein the acknowledgement message indicates that the multicast tree is established.

8. The method of claim 1, wherein the join message comprises a loopback address.

9. A network device comprising:

an interface configured to receive an acknowledgment-requesting join message specifying a multicast group; and

a routing module coupled to the interface, wherein the routing module is configured to;

determine whether a multicast tree corresponding to the multicast group already exists, in response to reception of the acknowledgment-requesting join message; and

send an acknowledgement corresponding to the acknowledgment-requesting join message, in response to a determination that the multicast tree already exists.

10. The network device of claim 9, wherein the routing module is configured to:

establish the multicast tree, without sending the acknowledgment message, in response to a determination that the multicast tree does not already exist.

11. The network device of claim 10, wherein the routing module is further configured to:

forward the join message to another network device toward a root of the multicast tree, in response to the determination that the multicast tree does not already exist.

12. The network device of claim 10, wherein the routing module is further configured to:

create multicast state information associated with the multicast group, wherein the multicast state information identifies the multicast tree.

13. The network device of claim 12, wherein the routing module is further configured to:

identify an outgoing interface leading to the first network device in the multicast state information.

14. The network device of claim 9, wherein the routing module is further configured to:

update multicast state information associated with the multicast group, in response to the determination that the multicast tree already exists, wherein

the multicast state information is updated with an outgoing interface leading to the first network device.

15. The network device of claim 9, wherein the acknowledgement message indicates that the multicast tree is established.

16. The network device of claim 9, wherein the join message comprises a loopback address.

17. A system comprising:

means for receiving a join message specifying a multicast group, wherein the join message is sent by a first network device, and

the join message requests acknowledgment;

means for determining whether tree corresponding to the multicast group already exists, in response to receipt of the join message; and

means for sending an acknowledgment message to the first network device, in response to a determination that the multicast tree already exists.

18. The system of claim 17, further comprising:

means for establishing the multicast tree, without sending the acknowledgement message, in response to a determination that the multicast tree does not already exist.

19. The system of claim 18, further comprising:

means for forwarding the join message to another network device toward a root of the multicast tree, in response to the determination that the multicast tree does not already exist.

20. The system of claim 18, further comprising:

means for creating multicast state information associated with the multicast group, wherein

the multicast state information identifies the multicast tree.