Efficient rendezvous point tree to shortest path tree switch-over process

• US 20030223372A1
• Filed: 06/04/2003
• Published: 12/04/2003
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Mehta, Apurva, Sanchez, Juan Diego
• Granted Patent: US 7,453,807 B2
• Time in Patent Office: Days
• US Class Current: 370/237
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• 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 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/15 in relation to multipoint traffic arrangements for broadcast or multicast in data networks H04L12/18

Abstract

A method of operating a network node in PIM-SM (Protocol Independent Multicast-Sparse Mode) is disclosed. In one embodiment, a Rendezvous Point Tree (RPT) to Shortest Path Tree (SPT) switch over process is initiated after the packet flow rate of the RPT data stream is compared against a predetermined threshold using a reverse rate limiting technique. If the packet flow rate of the RPT data stream exceeds the threshold, further analysis can be performed to decide whether the RPT to SPT switch over process should be initiated. Otherwise, if the packet flow rate does not exceed a predetermined threshold, the network node continues to receive multicast packets via the RPT until the predetermined threshold is reached.

Claims

1. A method for operating a network node, comprising:

receiving a stream of data packets from a source via an intermediate network node and forwarding the data packets to their respective destinations;

performing a reverse rate limiting process to determine whether a packet flow rate of the stream of data packets exceeds a predetermined threshold; and

depending on at least in part a result of the reverse rate limiting process, initiating a switch over process to cause data packets from the source to be routed along a network path that does not include the intermediate network node.

2. The method of claim 1, wherein the reverse rate limiting process comprises:

duplicating the stream of data packets;

dropping the duplicated stream of data packets if the packet flow rate of the duplicated stream is below or equals to the predetermined threshold; and

forwarding the duplicated stream of data packets to a processing unit of the network node if the packet flow rate exceeds the predetermined threshold.

3. The method of claim 2, wherein the initiating step comprises initiating the switch over process after the processing unit receives the duplicated stream of data packets.

4. The method of claim 1, wherein the stream of data packets comprise multicast data packets.

5. The method of claim 1, wherein the intermediate network node comprises a Rendezvous Point (RP) router.

6. The method of claim 1, wherein the switch over process comprises a Rendezvous Point Tree (RPT) to Shortest Path Tree (SPT) switch over process.

7. A network node, comprising:

one or more input ports configured to receive a stream data packets via an intermediate network node and one or more output ports configured to send the data packets to a plurality of host computers;

reverse rate limiting logic coupled to the input port, wherein the reverse rate limiting logic is configured to duplicate the stream of data packets, and wherein the reverse rate limiting logic is configured to output the duplicated stream if a packet flow rate of the duplicated stream is above a predetermined threshold; and

a processing unit coupled to the reverse rate limiting logic and configured to initiate a switch over process after the processing unit receives the duplicated stream from the reverse rate limiting logic, wherein the switch over process causes packet streams from the source to be sent to the network node without routing through the intermediate network node.

8. The network node of claim 7, wherein the reverse rate limiting logic is configured to drop data packets of the duplicated stream unless the packet flow rate of the duplicated stream is above a predetermined threshold.

9. The network node of claim 7, wherein the reverse rate limiting logic comprises rate limiting logic circuits programmed by micro-code.

10. The network node of claim 7, wherein the stream of data packets comprise multicast data packets.

11. The network node of claim 7, wherein the intermediate network node comprises a Rendezvous Point (RP) router.

12. The network node of claim 7, wherein the switch over process comprises a Rendezvous Point Tree to Shortest Path Tree switch over process.

13. A network node, comprising:

means for receiving a stream of data packets from a source via an intermediate network node and forwarding the data packets to their respective destinations;

means for performing a reverse rate limiting process to determine whether a packet flow rate of the stream exceeds a predetermined threshold; and

means for initiating a switch over process to cause data packets from the source to be routed along a network path that does not include the intermediate network node, wherein the means for initiating does not initiate the switch over process if the packet flow rate does not exceed the predetermined threshold.

14. The network node of claim 13, wherein the means for performing a reverse rate limiting process comprises:

means for duplicating the stream of data packets;

means for dropping the duplicated stream of data packets if the packet flow rate of the duplicated stream is below or equals to the predetermined threshold; and

means for forwarding the duplicated stream of data packets to the means for initiating if the packet flow rate exceeds the predetermined threshold.

15. The network node of claim 14, wherein the means for initiating comprises means for initiating the switch over process after receiving the duplicated stream of data packets.

16. The network node of claim 13, wherein the stream of data packets comprise multicast data packets.

17. The network node of claim 13, wherein the intermediate network node comprises a Rendezvous Point (RP) router.

18. The network node of claim 13, wherein the switch over process comprises a Rendezvous Point Tree to Shortest Path Tree switch over process.