SYSTEM AND METHOD FOR CONTROLLING A PHY ATTACHED TO A MAC INTERFACE FOR ENERGY EFFICIENT ETHERNET

• US 20090327506A1
• Filed: 06/30/2008
• Published: 12/31/2009
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Diab, Wael William
• Granted Patent: US 7,930,373 B2
• Time in Patent Office: Days
• US Class Current: 709/230
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/13 in a LAN segment, e.g. ring or bus
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: Y02D 30/00 Reducing energy consumption in communication networks

Abstract

A system and method for controlling a physical layer device attached to a media access control interface for energy efficient Ethernet. Detecting of a condition that is conducive to a change in a link rate can be performed at either link partner. In one embodiment, a control message based on the detection can be sent to a physical layer device via a media access control layer interface to effect a link rate change in the physical layer device.

Claims

1. An energy efficient Ethernet method, comprising:

detecting a condition that is conducive to a change in a link rate of an Ethernet link;

sending a message to a media access control layer that indicates said need to change a link rate of a physical layer device;

signaling, by said media access control layer to said physical layer device, an instruction to change said link rate of said physical layer device; and

changing an operating state of said physical layer device upon receipt of said instruction.

2. The method of claim 1, wherein said detecting comprises monitoring a buffer or queue.

3. The method of claim 1, wherein said detecting comprises monitoring a subsystem state.

4. The method of claim 1, wherein said signaling is done in band.

5. The method of claim 1, wherein said signaling is done out of band.

6. The method of claim 1, further comprising changing a rate of operation of said media access control layer after receipt of said message.

7. The method of claim 1, wherein said changing comprises switching to a subset physical layer device.

8. The method of claim 1, wherein said changing comprises switching to a low power idle mode.

9. The method of claim 1, wherein said changing comprises switching from a subset physical layer device to a parent physical layer device.

10. The method of claim 1, wherein said changing comprises switching from a low power idle mode to an active mode.

11. An energy efficient Ethernet system, comprising:

a physical layer device that has a plurality of modes of operation, wherein each of said plurality of modes of operation represent different levels of power consumption by said physical layer device; and

an interface that couples said physical layer device to a media access control layer, said interface enabling a communication of a link utilization change message from said media access control layer to said physical layer device, wherein said link utilization change message instructs said physical layer device to switch from a first mode of operation to a second mode of operation.

12. The system of claim 11, wherein said physical layer device supports parent and subset modes of operation.

13. The system of claim 11, wherein said physical layer device supports a low power idle mode of operation.

14. The system of claim 11, wherein said link utilization change message is produced in response to a condition detected by a layer above said media access control layer.

15. The system of claim 11, wherein said interface also enables a communication of a link utilization change report message from said physical layer device to said media access control layer, said link utilization change report message identifying a change in mode of operation that is initiated by a peer device.

16. The system of claim 11, wherein said link utilization change message is communicated using in band communication on said interface.

17. The system of claim 11, wherein said link utilization change message is communicated using out of band communication on said interface.

18. An energy efficient Ethernet method in a physical layer device, comprising:

receiving a link utilization change message via an interface that couples the physical layer device to a media access control layer; and

switching from a first link rate to a second link rate in response to a receipt of said link utilization change message, wherein one of said first link rate and said second link rate is lower than the other link rate.

19. The method of claim 18, wherein said receiving comprises receiving via in band signaling on said interface.

20. The method of claim 18, wherein said receiving comprises receiving via out of band signaling on said interface.

21. An energy efficient physical layer device in communication with a media access control device, comprising:

a multi-packet buffer that stores packets received from the media access control device; and

control logic that monitors a fullness of said multi-packet buffer and switching between a first mode of operation and a second mode of operation of the physical layer device based on said monitoring.

22. The physical layer device of claim 21, wherein said control logic monitors a fullness of said multi-packet buffer relative to a threshold.

23. The physical layer device of claim 21, wherein said multi-packet buffer is large enough to delay packet transmission in the physical layer device until the physical layer device has transitioned out of a low power state.

24. The physical layer device of claim 21, wherein said switching is not based on a control signal received from the media access control device.