SYSTEM AND METHOD FOR RE-ROUTING A MULTICAST STREAM

• US 20080095161A1
• Filed: 12/14/2007
• Published: 04/24/2008
• Est. Priority Date: 03/07/2006
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: XU, Xiaohu
• Granted Patent: US 8,050,264 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• 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
• CPC Class Codes: H04L 45/22 Alternate routing

Abstract

A method and system for re-routing a multicast stream is provided. The method for re-routing a multicast stream includes: providing a prior multicast forwarding path corresponding to a first route; establishing a new multicast forwarding path between a downstream router and a second upstream router corresponding to a second route; re-routing a multicast stream from said prior multicast forwarding path to said new multicast forwarding path, wherein said multicast stream utilizes said prior multicast forwarding path until said new multicast forwarding path is operational; and pruning said prior multicast forwarding path when said new multicast forwarding path is operational. Therefore, the multicast stream transmitting will not be interrupted during the switchover process of the multicast forwarding path caused by that a unicast route to a multicast source or a rendezvous point has changed.

Claims

1. A method for re-routing a multicast stream, comprising:

providing a prior multicast forwarding path corresponding to a first route;

establishing a new multicast forwarding path between a downstream router and a second upstream router corresponding to a second route;

re-routing a multicast stream from said prior multicast forwarding path to said new multicast forwarding path, wherein said multicast stream utilizes said prior multicast forwarding path until said new multicast forwarding path is operational; and

pruning said prior multicast forwarding path when said new multicast forwarding path is operational.

2. The method of claim 1, further comprising:

terminating said multicast stream received via said prior multicast forwarding path once said multicast stream is received via said new multicast forwarding path by said downstream router.

3. The method of claim 1, further comprising:

ignoring said multicast stream received via said prior multicast forwarding path once said multicast stream is received via said new multicast forwarding path by said downstream router.

4. The method of claim 1, wherein said establishing a new multicast forwarding path between a downstream router and a second upstream router comprises:

sending a Join message via a second incoming interface connected to said second upstream router; and

establishing said new multicast forwarding path from said second upstream router to said second incoming interface.

5. The method of claim 1, wherein said re-routing a multicast stream from said prior multicast forwarding path to said new multicast forwarding path comprises:

receiving said multicast stream via said second incoming interface by said downstream router; and

forwarding said multicast stream to a downstream device of said downstream router via an outgoing interface designated by said downstream router.

6. The claim of claim 1, wherein said pruning said prior multicast forwarding path comprises:

sending a Prune message to a first upstream router corresponding to said prior multicast forwarding path via a first incoming interface corresponding to said prior multicast forwarding path; and

pruning said prior multicast forwarding path from said first upstream router to said first incoming interface.

7. The method of claim 1, wherein said establishing a new multicast forwarding path between a downstream router and a second upstream router corresponding to a second route comprises:

when said prior multicast forwarding path is a source path tree, establishing a new source path tree if a unicast route from said downstream router to a multicast source of said multicast stream is changed from said first route to said second route.

8. The method of claim 7, wherein a unicast route from said downstream router to a multicast source of said multicast stream is changed from said first route to said second route comprises:

said unicast route from said downstream router to said multicast source of said multicast stream is changed from a second-best route to a best route.

9. The method of claim 1, wherein said establishing a new multicast forwarding path between a downstream router and a second upstream router comprises:

when said prior multicast forwarding path is a rendezvous point tree, establishing a new rendezvous point tree if a unicast route from said downstream router to a rendezvous point of said multicast stream is changed from said first route to said second route.

10. The method of claim 9, wherein a unicast route from said downstream router to a rendezvous point of said multicast stream is changed from said first route to said second route comprises:

said unicast route from said downstream router to said rendezvous point of said multicast stream is changed from a second-best route to a best route.

11. A system for re-routing a multicast stream, comprising:

a routing module, a forwarding module, a detecting module, an outgoing interface, a first incoming interface, and a second incoming interface, wherein

said first and second incoming interfaces are configured to receive a multicast stream from upstream routers, said first incoming interface is in communication with a first upstream router corresponding to a first route, and said second incoming interface is in communication with a second upstream router corresponding to a second route;

said outgoing interface is configured to forward said multicast stream to a downstream device;

said forwarding module is configured to forward said multicast stream to said outgoing interface pursuant to an instruction of said routing module wherein said multicast stream is received via an incoming interface designated by said routing module;

said detecting module is configured to detect a condition of receiving said multicast stream via said second incoming interface;

said routing module is configured to

send a first instruction to establish a new multicast forwarding path via said second incoming interface when a unicast route from a downstream router to a multicast source changes from said first route to said second route,

send a second instruction for pruning a prior multicast forwarding path corresponding to said first route via said first incoming interface upon said condition of receiving said multicast stream via said second incoming interface, and

instruct said forwarding module to forward said multicast stream to said outgoing interface, wherein said multicast stream is received via said second incoming interface.

12. The system of claim 11, wherein said routing module is configured to inform said first incoming interface to terminate said multicast stream received via said first incoming interface when said routing module is informed that said detecting module detects that said multicast stream is received via said second incoming interface.

13. The system of claim 11, wherein said routing module is configured to send a Join message to said second upstream router via said second incoming interface to establish said new multicast forwarding path.

14. The system of claim 11, wherein said routing module is configured to send a Prune message to said first upstream router via said first incoming interface to prune said prior multicast forwarding path.

15. A system for re-routing a multicast stream, comprising:

a multicast source, connected to a first router; and

a multicast receiver, connected to a third router;

wherein

said first and third routers are connected to each other and a second router;

a multicast stream is re-routed from a prior multicast forwarding path to a new multicast path, wherein said multicast stream utilizes said prior multicast forwarding path until said new multicast forwarding path is operational; and

said first router and said third router define said new multicast forwarding path and said first, second and third router define said prior multicast forwarding path.

16. A system of claim 15, wherein said third router comprises:

a routing module, a forwarding module, a detecting module, an outgoing interface, a first incoming interface, and a second incoming interface, wherein

said first and second incoming interfaces are configured to receive a multicast stream from upstream routers, said first incoming interface is in communication with a first upstream router corresponding to a first route, and said second incoming interface is in communication with a second upstream router corresponding to a second route;

said outgoing interface is configured to forward said multicast stream to a downstream device;

said forwarding module is configured to forward said multicast stream to said outgoing interface pursuant to an instruction of said routing module wherein said multicast stream is received via an incoming interface designated by said routing module;

said detecting module is configured to detect a condition of receiving said multicast stream via said second incoming interface;

said routing module is configured to

send a first instruction to establish a new multicast forwarding path via said second incoming interface when a unicast route from a downstream router to a multicast source changes from said first route to said second route,

send a second instruction for pruning a prior multicast forwarding path corresponding to said first route via said first incoming interface upon said condition of receiving said multicast stream via said second incoming interface, and

instruct said forwarding module to forward said multicast stream to said outgoing interface, wherein said multicast stream is received via said second incoming interface.