Acknowledgement-based rerouting of multicast traffic

• US 8,144,628 B2
• Filed: 01/18/2006
• Issued: 03/27/2012
• 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: Previdi, Stefano, Farinacci, Dino, Wijnands, Ijsbrand, Boers, Arjen
• Primary Examiner(s): Ton, Dang
• Assistant Examiner(s): KAVLESKI, RYAN C
• Application Number:
  US11/333,843
• Publication Number:
  US 20070133530A1
• Time in Patent Office: 2,260 Days
• Field of Search: 370/256, 370/408, 370/432, 709/227, 709/229
• US Class Current: 370/256
• 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, wherein

multicast forwarding information and multicast routing information are associated with the multicast group, and

prior to the join message being sent, the multicast routing information and the multicast forwarding information identify a current multicast tree;

in response to sending the join message,

inhibiting updating of the multicast forwarding information to identify the multicast tree, until receipt of an acknowledgement message corresponding to the join message; and

updating the multicast routing information to identify the new multicast tree, prior to the receipt of the acknowledgement message, wherein

the sending, the inhibiting updating, and the updating are performed by a network device.

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, wherein the multicast routing information is updated to identify a new reverse path forwarding neighbor, in response to identifying the new multicast tree.

4. The method of claim 3, wherein the multicast forwarding information is updated to identify a new reverse path forwarding interface, in response to the receipt of the acknowledgement message 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 acknowledgement message corresponding to the join message is received.

7. A network device comprising:

a storage module comprising multicast forwarding information and multicast routing information, wherein

the multicast forwarding information and the multicast routing information are associated with a multicast group; and

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

send a join message specifying the multicast group towards a root of a new multicast tree, wherein

prior to the join message being sent, the multicast forwarding information and the multicast routing information identify a current multicast tree;

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

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

8. The network device of claim 7, wherein

the routing module is further configured to, in response to the receipt of the indication that the new multicast tree has been established:

update the multicast forwarding information to identify the new multicast tree, and

send a prune message on the current multicast tree.

9. The network device of claim 7, wherein

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

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

10. The network device of claim 7, 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.

11. The network device of claim 7, wherein the join message comprises a loopback address.

12. A system comprising:

a first network device configured to;

send a join message for a multicast group towards a root of a new multicast tree, wherein

multicast forwarding information and multicast routing information are associated with the multicast group, and

prior to the join message being sent, the multicast forwarding information and the multicast routing information identify a current multicast tree;

in response to the join message being sent,

inhibit updating the multicast forwarding information to identify the new multicast tree until receipt of an acknowledgement message corresponding to the join message; and

update the multicast routing information to identify the new multicast tree, until prior to the receipt of the acknowledgement message.

13. The system of claim 12, further comprising:

a second network device coupled to the first network device, 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 acknowledgement message to the first network device, if the multicast state already exists.

14. The system of claim 12, 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.

15. A system comprising:

means for sending, from a network device, a join message for a multicast group towards a root of a new multicast tree, wherein

multicast forwarding information and multicast routing information are associated with the multicast group, and

prior to the join message being sent, the multicast forwarding information and the multicast routing information identify a current multicast tree;

in response to sending the join message,

means for inhibiting, on the network device, updating of the multicast forwarding information to identify the new multicast tree, until receipt of an acknowledgement message corresponding to the join message; and

means for updating, on the network device, multicast routing information to identify the new multicast tree, prior to the receipt of the acknowledgement.