Techniques for Reliable Switchover to a Date Multicast Distribution Tree (MDT)

• US 20120057594A1
• Filed: 11/15/2011
• Published: 03/08/2012
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Boers, Arjen, Wijnands, Ijsbrand, Bhaskar, Nidhi
• Granted Patent: US 8,761,161 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways

Abstract

Techniques reliably provide the switchover from a default MDT to the data MDT by using reliable signaling and reliable building of a data MDT. The message notifying of the pending switchover to the data MDT is reliably sent using signaling that is reliable. Also, the switchover from the default MDT to the data MDT does not happen until all egress routers have responded to the message. Egress routers join the data MDT if associated receivers are interested in receiving the multicast stream from a source. The router does not send another response upstream until all egress routers downstream from it respond to the message in the positive or the negative.

Claims

1. A method comprising:

accessing a first router configured to broadcast data from a source to a plurality of routers, the first router broadcasting the data as a default multicast distribution tree (MDT), the default MDT broadcasting the data to all of the plurality of routers;

determining, at the first router, whether to switch from the default MDT to a data MDT, the data MDT broadcasting the data to a portion of the plurality of routers;

determining, at the first router, which of the plurality of routers comprises the portion of routers that receives the content from the data MDT; and

upon determining which of the routers comprise the portion of the plurality of routers, switching the first router to broadcast the data from the default MDT to the data MDT.

2. The method of claim 1 further comprising determining, in the first router, a list of routers in the plurality of routers using the default MDT, the list of routers comprising all of the routers in the default MDT.

3. The method of claim 2, wherein the list of routers in the plurality comprises one of a plurality of default MDT lists.

4. The method of claim 1, wherein the determining of the portion of the plurality comprises:

sending a request message from the first router to all of the plurality of routers to join the data MDT, and receiving a response to the request from all of the plurality of routers.

5. The method of claim 4, wherein the determining of the portion of plurality further comprises determining whether all of the plurality of routers have responded to the request message.

6. The method of claim 4, wherein the response to the request comprises an indication whether a second router wants to join the data MDT, the second router being part of the plurality of routers.

7. The method of claim 6, wherein the indication includes routing information that is used to route data to the second router in the MDT.

8. The method of claim 4, wherein the request message is sent through one of transfer control protocol (TCP) or border gateway protocol (BGP).

9. The method of claim 4, further comprising building the data MDT using information in the response.

10. A network device comprising:

one or more processors; and

a computer readable memory containing instructions that, when executed by the one or more computer processors, cause the one or more computer processors to perform a set of steps comprising;

accessing a first router configured to broadcast data from a source to a plurality of routers, the first router broadcasting the data as a default multicast distribution tree (MDT), the default MDT broadcasting the data to all of the plurality of routers;

determining, at the first router, whether to switch from the default MDT to a data MDT, the data MDT broadcasting the data to a portion of the plurality of routers;

determining, at the first router, which of the plurality of routers comprises the portion of routers that receives the content from the data MDT; and

upon determining which of the routers comprise the portion of the plurality of routers, switching the first router to broadcast the data from the default MDT to the data MDT.

11. The network device of claim 10, wherein the set of steps further comprises determining, in the first router, a list of routers in the plurality of routers using the default MDT, the list of routers comprising all of the routers in the default MDT.

12. The network device of claim 11, wherein the list of routers in the plurality comprises one of a plurality of default MDT lists.

13. The network device of claim 10, wherein the determining of the portion of the plurality comprises:

sending a request message from the first router to all of the plurality of routers to join the data MDT, and

receiving a response to the request from all of the plurality of routers.

14. The network device of claim 13, wherein the determining of the portion of plurality further comprises determining whether all of the plurality of routers have responded to the request message.

15. The network device of claim 13, wherein the response to the request comprises an indication whether a second router wants to join the data MDT, the second router being part of the plurality of routers.

16. The network device of claim 13, wherein the indication includes routing information that is used to route data to the second router in the MDT.

17. The network device of claim 13, wherein the request message is sent through one of transfer control protocol (TCP) or border gateway protocol (BGP).

18. The network device of claim 13, further comprising building the data MDT using information in the response.

19. A non-transitory computer readable medium including instructions executable by one or more processors for:

accessing a first router configured to broadcast data from a source to a plurality of routers, the first router broadcasting the data as a default multicast distribution tree (MDT), the default MDT broadcasting the data to all of the plurality of routers;

determining, at the first router, whether to switch from the default MDT to a data MDT, the data MDT broadcasting the data to a portion of the plurality of routers;

determining, at the first router, which of the plurality of routers comprises the portion of routers that receives the content from the data MDT; and

upon determining which of the routers comprise the portion of the plurality of routers, switching the first router to broadcast the data from the default MDT to the data MDT.

20. The non-transitory computer readable medium of claim 19 further comprising instructions executable by one or more processors for:

sending a request message from the first router to all of the plurality of routers to join the data MDT, and

receiving a response to the request from all of the plurality of routers.