Acknowledgement-based rerouting of multicast traffic

• US 20070133530A1
• Filed: 01/18/2006
• Published: 06/14/2007
• Est. Priority Date: 12/13/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Farinacci, Dino, Boers, Arjen, Wijnands, Ijsbrand, Previdi, Stefano
• Granted Patent: US 8,144,628 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• 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:

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.

2. The method of claim 1, further comprising:

detecting a topology change within a network;

identifying the new multicast tree, in response to detection of the topology change.

3. The method of claim 2, further comprising:

updating multicast routing information corresponding to the multicast group to identify a new reverse path forwarding neighbor, in response to identifying the new multicast tree.

4. The method of claim 3, further comprising:

updating multicast forwarding information corresponding to the multicast group to identify a new reverse path forwarding interface, in response to receiving the acknowledgment corresponding to the join message.

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

6. The method of claim 1, further comprising:

dropping multicast packets received via the new multicast tree, until the acknowledgment corresponding to the join message is received.

7. 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;

identifying whether state information corresponding to the multicast group already exists; and

sending an acknowledgment message to the first network device, if the multicast state information already exists.

8. The method of claim 7, further comprising:

inhibiting sending the acknowledgment to the first network device, if the multicast state information does not already exist; and

forwarding the join message to another network device.

9. A network device comprising:

multicast forwarding information, wherein the multicast forwarding information is associated with a multicast group and identifies a multicast tree;

a routing module coupled to access the multicast forwarding information, wherein the routing module is configured to;

send a join message specifying the multicast group towards a root of a new multicast tree; and

inhibit updating the maintain the multicast forwarding information to identify the new multicast tree until receipt of an indication that the new multicast tree has been established.

10. The network device of claim 9, further comprising:

multicast routing information associated with the multicast group, wherein

prior to the join message being sent, the multicast routing information identifies the multicast tree, and

the routing module is configured to update the multicast routing information to identify the new multicast tree prior to receipt of the indication that the new multicast tree has been established.

11. The network device of claim 9, wherein

the join message is an acknowledgment-requesting join message, and

the indication that the new multicast tree has been established comprises an acknowledgment corresponding to the acknowledgment-requesting join message.

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

detect a topology change within a network;

identify the new multicast tree, in response to detection of the topology change.

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

14. 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;

identify whether a multicast state information 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, if the multicast state information already exists.

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

inhibit sending the acknowledgment to the first network device, if the multicast state information does not already exist; and

forward the join message to another network device.

16. A system comprising:

a first network device;

a second network device coupled to the first network device, wherein

the first network device is configured to;

send a join message for a multicast group towards a root of a new multicast tree; and

forward multicast traffic, addressed to the multicast group, on a current multicast tree until an acknowledgment corresponding to the join message is received.

17. The system of claim 16, wherein

the second network device is configured to:

receive the join message,

identify whether a multicast state corresponding to the multicast group already exists, and

send the acknowledgment message to the first network device, if the multicast state already exists.

18. The system of claim 16, wherein the first network device is configured to:

detect a topology change within a network; and

identify the new multicast tree, in response to detection of the topology change.

19. A system comprising:

means for sending a join message for a multicast group towards a root of a new multicast tree; and

means for forwarding multicast traffic, addressed to the multicast group, on a current multicast tree, until an acknowledgment corresponding to the join message is received.

20. 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 identifying whether state information corresponding to the multicast group already exists; and

means for sending an acknowledgment message to the first network device, if the multicast state information already exists.