Congestion indication for flow control

• US 20030156542A1
• Filed: 02/19/2002
• Published: 08/21/2003
• Est. Priority Date: 02/19/2002
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Connor, Patrick L.
• Granted Patent: US 7,474,616 B2
• Time in Patent Office: Days
• US Class Current: 370/236
• CPC Class Codes: H04L 12/40013 Details regarding a bus controller
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04W 28/12 using signalling between network elements
• CPC Class Codes: H04W 28/14 using intermediate storage
• CPC Class Codes: H04W 28/22 Negotiating communication rate

Abstract

A method, apparatus, and signal-bearing medium for indicating and responding to congestion in a network. When a buffer at a receiver is nearly full, the receiver may send a congestion indication to the sender(s) that is causing the congestion. When the receiver(s) receives the congestion indication, it may implement a flow-control technique to temporarily lower the rate that it is sending the frames to the receiver, and then increase the rate.

Claims

1. A method comprising:

determining that a received frame causes a buffer to exceed a threshold;

determining an end-point to receive a congestion-indication frame in response to the exceeded threshold;

building the congestion-indication frame, wherein the congestion-indication frame indicates that future frames should temporarily be sent at a lower rate; and

sending the congestion-indication frame to a link-partner.

2. The method of claim 1, wherein the determining the end-point further comprises:

determining the end-point based on a source of the received frame.

3. The method of claim 1, wherein the determining the end-point further comprises:

determining the end-point based on amounts of data in the buffer from a plurality of sources.

4. The method of claim 3, wherein the determining the end-point further comprises:

determining the end-point based on times that the data in the buffer was received.

5. The method of claim 4, wherein the determining the end-point further comprises:

selecting the end-point that has sent the most data within a most-recent time period.

6. The method of claim 1, wherein the determining that the received frame causes the buffer to exceed the threshold further comprises:

determining that the received frame causes the buffer to exceed a percentage of a size of the buffer.

7. A signal-bearing medium bearing a data structure, comprising:

an identifier field to identify that a first end-point is congested;

a data-link-layer flow control field to indicate that an electronic device is to pause sending frames to the receiving end-point;

a data-link-layer flow control valid-indicator field to indicate whether the data-link-layer flow control field is valid; and

a throughput-capability field to indicate a link speed of the first end-point.

8. The signal-bearing medium of claim 7, wherein the data structure further comprises:

a network-layer header comprising an address of a second end-point, wherein the second end-point is to receive the data structure.

9. The signal-bearing medium of claim 8, wherein the electronic device is a link partner of the first end-point.

10. The signal-bearing medium of claim 9, wherein the second end-point is to receive the data structure from the link partner.

11. An apparatus, comprising:

a media access controller to receive a frame from a first end-point, determine that the frame contains pause information, invalidate the pause information in the frame, and pause sending future frames to the first end-point.

12. The apparatus of claim 11, wherein the media access controller is further to send the frame to a second end-point.

13. The apparatus of claim 11, further comprising:

a buffer, wherein the media access controller is further to save the future frames in the buffer.

14. The apparatus of claim 13, wherein the media access controller is further to pause sending the future frames to the first end-point for a period of time, after which the media access controller is to send the future frames to the first end-point.

15. A signal-bearing medium bearing instructions, which when read and executed by an electronic device comprise:

sending frames to a receiver;

receiving a congestion indication; and

sending future frames to the receiver at a lower rate for a period of time in response to the congestion indication.

16. The signal-bearing medium of claim 15, wherein the instructions further comprise:

determining that pause information in the congestion indication is invalid.

17. The signal-bearing medium of claim 15, wherein the instructions further comprise:

after the period of time expires, increasing the lower rate.

18. The signal-bearing medium of claim 17, wherein increasing the lower rate further comprises:

increasing a size of a send window until the size of the send window equals a size of a receive window.

19. The signal-bearing medium of claim 17, wherein the receiving the congestion indication further comprises:

receiving the congestion indication from a link partner of the receiver.

20. The signal-bearing medium of claim 19, wherein the instructions further comprise:

determining that a received frame contains the congestion indication.

21. The signal-bearing medium of claim 20, wherein increasing the lower rate further comprises:

increasing the lower rate based on throughput information in the received frame.

22. An apparatus comprising:

a first end-point to determine that an amount of data in a buffer has exceeded a threshold and build a congestion-indication frame comprising pause information; and

a link partner to receive the congestion-indication frame from the first end-point, invalidate the pause information in the congestion-indication frame, and send the congestion-indication frame to a second end-point.

23. The apparatus of claim 22 wherein the first end-point is further to:

store throughout information in the congestion-indication frame.

24. The apparatus of claim 22, wherein the first end-point is further to:

store an address of the second end-point in the congestion-indication frame.

25. The apparatus of claim 24, wherein the first end-point is further to:

build a network-layer header comprising the address of the second end-point.

26. The apparatus of claim 22 wherein the link partner is further to:

pause sending future frames to the first end-point for a period of time in response to the pause information.