SOURCE ROOTED MULTICAST (SRM)

• US 20130343384A1
• Filed: 06/26/2012
• Published: 12/26/2013
• Est. Priority Date: 06/26/2012
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: FARINACCI, Dino, SHEPHERD, Gregory J., BYZEK, Jeff
• Granted Patent: US 8,848,709 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/72 Routing based on the source address

Abstract

Methods and apparatus for source rooted multicast (SRM) are provided. As defined herein, SRM generally refers to associating outgoing interface lists (OILs) in the forwarding entry with the source address instead of the group address and aggregating the resulting multicast forwarding states. In this manner, the amount of forwarding state may be reduced, especially in deployments where many hosts are all running the same application and using the same group. One example method generally includes—for each of a plurality of multicast forwarding states associated with a multicast group, wherein each multicast forwarding state is referenced by a source address representing a multicast source and is associated with an outgoing interface list—associating the outgoing interface list with the source address; and aggregating the two or more of the multicast forwarding states having the outgoing interface lists associated with the source addresses to form one or more aggregated forwarding states.

Claims

1. A method, comprising:

for each of a plurality of multicast forwarding states associated with a multicast group, wherein each multicast forwarding state is referenced by a multicast source address and is associated with an outgoing interface list, associating the outgoing interface list with the source address; and

aggregating two or more of the multicast forwarding states having the outgoing interface lists associated with the source addresses to form one or more aggregated forwarding states.

2. The method of claim 1, wherein the number of aggregated forwarding states is less than or equal to the number of multicast forwarding states.

3. The method of claim 1, further comprising, routing packets based on the aggregated forwarding states.

4. The method of claim 1, wherein the aggregating comprises aggregating the multicast forwarding states based on matching outgoing interfaces (OIFs) and incoming interfaces (IIFs).

5. The method of claim 4, wherein the aggregating comprises further aggregating at least one of the aggregated forwarding states based on a source address prefix on a power-of-2 boundary.

6. The method of claim 1, wherein the aggregated forwarding states are compatible with Protocol Independent Multicast Source Specific Multicast (PIM-SSM).

7. The method of claim 1, further comprising, sending a join message for the multicast group to an upstream neighbor based on the aggregated forwarding states.

8. The method of claim 7, further comprising receiving a message indicating that the upstream neighbor supports aggregated forwarding states.

9. An apparatus comprising:

at least one processing unit configured to;

associate—

for each of a plurality of multicast forwarding states associated with a multicast group, wherein each multicast forwarding state is referenced by a multicast source address and is associated with an outgoing interface list—

the outgoing interface list with the source address; and

aggregate two or more of the multicast forwarding states having the outgoing interface lists associated with the source addresses to form one or more aggregated forwarding states.

10. The apparatus of claim 9, wherein the at least one processing unit is further configured to route packets based on the aggregated forwarding states.

11. The apparatus of claim 9, wherein the at least one processing unit is configured to aggregate the multicast forwarding states based on matching outgoing interfaces (OIFs) and incoming interfaces (IIFs).

12. The apparatus of claim 11, wherein the at least one processing unit is configured to further aggregate at least one of the aggregated forwarding states based on a source address prefix on a power-of-2 boundary.

13. The apparatus of claim 9, wherein the aggregated forwarding states are compatible with Protocol Independent Multicast Source Specific Multicast (PIM-SSM).

14. The apparatus of claim 9, wherein the at least one processing unit is configured to send a join message for the multicast group to an upstream neighbor based on the aggregated forwarding states.

15. The apparatus of claim 14, wherein the at least one processing unit is configured to receive a message indicating that the upstream neighbor supports aggregated forwarding states.

16. An apparatus comprising:

means for associating—

for each of a plurality of multicast forwarding states associated with a multicast group, wherein each multicast forwarding state is referenced by a source address representing a multicast source and is associated with an outgoing interface list—

the outgoing interface list with the source address; and

means for aggregating two or more of the multicast forwarding states having the outgoing interface lists associated with the source addresses to form one or more aggregated forwarding states.

17. The apparatus of claim 16, further comprising means for routing packets based on the aggregated forwarding states.

18. The apparatus of claim 16, wherein the means for aggregating is configured to aggregate the multicast forwarding states based on matching outgoing interfaces (OIFs) and incoming interfaces (IIFs).

19. The apparatus of claim 18, wherein the means for aggregating is configured to further aggregate at least one of the aggregated forwarding states based on a source address prefix on a power-of-2 boundary.

20. The apparatus of claim 16, wherein the aggregated forwarding states are compatible with Protocol Independent Multicast Source Specific Multicast (PIM-SSM).