Intelligent congestion feedback apparatus and method

• US 20060092836A1
• Filed: 10/27/2005
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Agarwal, Puneet, Kwan, Bruce H.
• Granted Patent: US 7,859,996 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/2466 using signalling traffic
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/265 sent by intermediate network nodes
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/31 by tagging of packets, e.g. using discard eligibility [DE] bits
• CPC Class Codes: H04L 47/33 using forward notification

Abstract

An intelligent congestion feedback apparatus and method thereof includes a source endpoint transmitting data packets, and a destination endpoint receiving the data packets, and a timer in the destination endpoint set to zero. An intermediate node detects congestion between the source endpoint and the destination endpoint. Upon congestion detection, the intermediate node marks the data packets transmitted to the destination endpoint indicative of congestion. Upon receipt of the marked data packets, the timer begins reverse counting from a preset time value to zero and a feedback loop is turned-on between the destination endpoint and the source endpoint to transmit congestion notification (CN) messages to the source endpoint contributing to the congestion.

Claims

1. An intelligent congestion feedback apparatus, comprising:

a source endpoint transmitting data packets;

a destination endpoint receiving the data packets;

a timer in the destination endpoint set to zero; and

an intermediate node detecting congestion between the source endpoint and the destination endpoint, wherein

upon congestion detection, the intermediate node marks the data packets transmitted to the destination endpoint indicative of congestion, and

upon receipt of the marked data packets, the timer begins reverse counting from a preset time value to zero and a feedback loop is turned-on between the destination endpoint and the source endpoint to transmit congestion notification (CN) messages to the source endpoint contributing to the congestion.

2. The intelligent congestion feedback apparatus as recited in claim 1, wherein headers of the data packets are marked with a congestion notification bit tag.

3. The intelligent congestion feedback apparatus as recited in claim 1, wherein when the timer reaches zero, the destination endpoint stops sending the CN messages and terminates the feedback loop.

4. The intelligent congestion feedback apparatus as recited in claim 1, wherein when the timer is counting down from the preset time value to zero and the destination endpoint receives another marked data packet from the source endpoint indicative of congestion, the timer is reset back to the preset time value and resumes count down.

5. The intelligent congestion feedback apparatus as recited in claim 1, wherein when the destination endpoint receives a user configurable number of unmarked data packets and the timer has not reached zero, the destination endpoint terminates the feedback loop and the timer is set to zero.

6. The intelligent congestion feedback apparatus as recited in claim 1, wherein, for each CN message, the destination node sets an explicit congestion notification-echo flag in an acknowledgment (ACK) packet associated with each marked data packet.

7. The intelligent congestion feedback apparatus as recited in claim 1, wherein each CN message comprises an SrcEndpointAddress field, a DestEndpointAddress field, and a CongestionState field.

8. The intelligent congestion feedback apparatus as recited in claim 1, wherein the timer is provided for each source endpoint per class of service.

9. The intelligent congestion feedback apparatus as recited in claim 1, wherein the preset time value of the timer is set depending upon a responsiveness of the source endpoint in correcting the congestion at the intermediate node, a number of source endpoints contributing to the congestion, and/or a degree of congestion.

10. The intelligent congestion feedback apparatus as recited in claim 1, wherein the preset time value defines a period of time that the destination endpoint is to maintain the feedback loop turned-on for transmitting the CN messages back to the source endpoint.

11. The intelligent congestion feedback apparatus as recited in claim 1, wherein, upon receipt of the CN message, the source endpoint contributing to the congestion interrupts or reduce a rate of transmission of the data packets to the intermediate node per class of service without affecting the transmission of the data packets corresponding to other classes of service.

12. An intelligent congestion feedback method, comprising:

transmitting data packets from a source endpoint;

receiving the data packets at a destination endpoint;

detecting congestion between the source endpoint and the destination endpoint;

marking the data packets transmitted to the destination endpoint indicative of congestion;

reverse counting from a preset time value to zero; and

turning-on a feedback loop between the destination endpoint to the source endpoint to transmit congestion notification (CN) messages to the source endpoint contributing to the congestion.

13. The intelligent congestion feedback method as recited in claim 12, further comprising:

marking the data packets with a congestion notification bit tag.

14. The intelligent congestion feedback method as recited in claim 12, further comprising:

stopping sending the CN messages and terminating the feedback loop when the reverse counting reaches zero.

15. The intelligent congestion feedback method as recited in claim 12, further comprising:

using a timer to perform the reverse counting from the preset time value to zero;

resetting the timer back to the preset time value and resuming the reverse counting when the destination endpoint receives another marked data packet from the source endpoint.

16. The intelligent congestion feedback method as recited in claim 12, further comprising:

using a timer to perform the reverse counting from the preset time value to zero;

terminating the feedback loop and setting the timer to zero when the destination endpoint receives a user configurable number of unmarked data packet and the timer has not reached zero.

17. The intelligent congestion feedback method as recited in claim 12, further comprising:

providing a timer to perform the reverse counting from the preset time value to zero for each source endpoint per class of service.

18. The intelligent congestion feedback method as recited in claim 12, further comprising:

adjusting the preset time value depending upon a responsiveness of the source endpoint in correcting the congestion at the intermediate node, a number of source endpoints contributing to the congestion, and/or a degree of congestion.

19. The intelligent congestion feedback method as recited in claim 12, further comprising:

setting, for each CN message, an explicit congestion notification flag in a packet associated with each marked data packet.

20. The intelligent congestion feedback method as recited in claim 12, further comprising:

setting, for each CN message, an SrcEndpointAddress field, a DestEndpointAddress field, and a CongestionState field.

21. The intelligent congestion feedback method as recited in claim 12, further comprising:

defining the preset time value to zero as a period of time to maintain the feedback loop turned-on for transmitting the CN messages back to the source endpoint.

22. The intelligent congestion feedback method as recited in claim 12, further comprising:

mapping the CN message to a highest priority class of service queue when transmitting the CN message to the source endpoint.

23. The intelligent congestion feedback method as recited in claim 12, wherein, upon receipt of the CN message, the method further comprises:

interrupting or reducing a rate of transmission of the data packets from the source contributing to the congestion to the intermediate node on a per class of service without affecting the transmission of the data packets corresponding to other classes of service.

24. An intelligent congestion feedback apparatus, comprising:

source endpoint means for transmitting data packets;

destination endpoint means for receiving the data packets;

timing means in the destination endpoint means set to zero; and

intermediate means for detecting congestion between the source endpoint and the destination endpoint, wherein

upon congestion detection, the intermediate means marks the data packets transmitted to the destination endpoint indicative of congestion, and

upon receipt of the marked data packets, the timing means begins reverse counting from a preset time value to zero and a feedback loop is turned-on between the destination endpoint means and the source endpoint means for transmitting congestion notification (CN) messages to the source endpoint contributing to the congestion.