Bidirectional multicast protocol with upstream and downstream join messages

• US 20070091891A1
• Filed: 10/26/2005
• Published: 04/26/2007
• Est. Priority Date: 10/26/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Farinacci, Dino, Zwiebel, John
• Granted Patent: US 7,808,993 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 45/16 Multipoint routing

Abstract

Systems and methods for implementing a bidirectional multicast protocol with two types of join messages are disclosed. The two types of join messages, upstream joins and downstream joins, are used to control the Reverse Path Forwarding (RPF) interface is added to the outgoing interface list for a particular multicast group, which in turn controls when multicast packets will be forwarded to the rendezvous point. One method involves receiving a multicast packet addressed to multicast group G. The method inhibits the multicast packet from being forwarded via the RPF interface, unless the outgoing interface list corresponding to the multicast group G already identifies the RPF interface. The RPF interface can be added to the outgoing interface list in response to reception of a downstream join message via the RPF interface, as well as in response to monitoring, via the RPF interface, an upstream join message on a shared network segment.

Claims

1. A method comprising:

receiving a multicast packet addressed to multicast group G, wherein

multicast routing for multicast group G is performed using a bidirectional multicast routing protocol; and

inhibiting the multicast packet from being forwarded via the interface leading towards the rendezvous point, unless an outgoing interface list corresponding to the multicast group G identifies the interface.

2. The method of claim 1, further comprising:

generating (*, G) state information for the multicast group G, in response to receiving an indication that a receiver is joining the multicast group, wherein

the indication is received via an interface that does not lead to a rendezvous point,

the (*, G) state information includes the outgoing interface list, and

the outgoing interface list does not identify the interface leading towards the rendezvous point.

3. The method of claim 2, further comprising:

receiving a downstream join message identifying the multicast group G; and

adding, to the outgoing interface list, information identifying the interface leading towards the rendezvous point, in response to receiving the downstream join message.

4. The method of claim 2, further comprising:

detecting an upstream join message specifying the multicast group G, wherein

the upstream join message is detected by monitoring a shared network segment; and

adding, to the outgoing interface list, information identifying the interface leading towards the rendezvous point, in response to detecting the upstream join message.

5. The method of claim 2, further comprising:

sending a downstream join message identifying the multicast group G to one or more downstream network devices.

6. The method of claim 5, wherein

the sending the downstream join message is performed in response to at least one of:

more than one outgoing interface being identified in the outgoing interface list;

the interface leading to the rendezvous point being identified in the outgoing interface list; and

only one of a plurality of downstream interfaces being identified in the outgoing interface list, wherein if the outgoing interface lists only one of the downstream interfaces, the sending the downstream join message comprises sending the downstream join message from each downstream interface other than the one of the downstream interfaces identified in the outgoing interface list.

7. The method of claim 6, wherein

the sending the downstream join message comprises sending the downstream join message from each one of a plurality of interfaces.

9. The node of claim 1, wherein the bidirectional multicast routing module is further configured to:

generate (*, G) state information for a multicast group G, in response to reception of an indication that a receiver is joining the multicast group, wherein

the (*, G) state information includes the outgoing interface list, and

the outgoing interface list does not identify the RPF interface.

10. The node of claim 9, wherein the bidirectional multicast routing module is further configured to:

add, to the outgoing interface list, information identifying the RPF interface, in response to reception of a downstream join message identifying the multicast group G.

11. The node of claim 9, wherein

the RPF interface module is configured to detect an upstream join message specifying the multicast group G,

the upstream join message is detected by monitoring a shared network segment, and

the bidirectional multicast routing module is configured to add, to the outgoing interface list, information identifying the RPF interface, in response to detection of the upstream join message.

12. The node of claim 9, wherein

the bidirectional multicast routing module is configured to send a downstream join message identifying the multicast group G to one or more downstream network devices.

13. The node of claim 12, wherein

the downstream join message is sent in response to at least one of:

more than one outgoing interface being identified in the outgoing interface list;

the RPF interface being identified in the outgoing interface list; and

only one of a plurality of downstream interfaces being identified in the outgoing interface list, wherein if the outgoing interface lists only one of the downstream interfaces, the downstream join message is sent from each downstream interface other than the one of the downstream interfaces identified in the outgoing interface list.

8. A node comprising:

an interface, wherein

the interface is configured to receive a multicast packet addressed to multicast group G;

a Reverse Path Forwarding (RPF) interface coupled to send packets towards a rendezvous point; and

a bidirectional multicast routing module coupled to the interface and the RPF interface, wherein

the bidirectional multicast routing module is configured to inhibit the multicast packet from being forwarded via the RPF interface, unless an outgoing interface list corresponding to multicast group G identifies the RPF interface.

14. A system comprising:

means for receiving a multicast packet addressed to multicast group G, wherein

multicast routing for multicast group G is performed using a bidirectional multicast routing protocol; and

means for inhibiting the multicast packet from being forwarded via the interface leading towards the rendezvous point, unless an outgoing interface list corresponding to the multicast group G identifies the interface.

15. The system of claim 14, further comprising:

means for generating (*, G) state information for the multicast group G, in response to receiving an indication that a receiver is joining the multicast group, wherein

the indication is received via an interface that does not lead to a rendezvous point,

the (*, G) state information includes the outgoing interface list, and

the outgoing interface list does not identify the interface leading towards the rendezvous point.

16. The system of claim 15, further comprising:

means for receiving a downstream join message identifying the multicast group G; and

means for adding, to the outgoing interface list, information identifying the interface leading towards the rendezvous point, in response to receiving the downstream join message.

17. The system of claim 15, further comprising:

means for detecting an upstream join message specifying the multicast group G, wherein

the upstream join message is detected by monitoring a shared network segment; and

means for adding, to the outgoing interface list, information identifying the interface leading towards the rendezvous point, in response to detecting the upstream join message.

18. The system of claim 15, further comprising:

means for sending a downstream join message identifying the multicast group G to one or more downstream network devices.

19. The system of claim 18, wherein

the downstream join message is sent in response to at least one of:

more than one outgoing interface being identified in the outgoing interface list;

the RPF interface being identified in the outgoing interface list; and

only one of a plurality of downstream interfaces being identified in the outgoing interface list, wherein if the outgoing interface lists only one of the downstream interfaces, the downstream join message is sent from each downstream interface other than the one of the downstream interfaces identified in the outgoing interface list.