Priority aware MAC flow control

• US 7,990,857 B2
• Filed: 11/09/2009
• Issued: 08/02/2011
• Est. Priority Date: 10/23/2003
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Foundry Networks LLC (Broadcom, Inc.)
• Inventors: Jain, Nitin, Jalan, Rajkumar
• Primary Examiner(s): Sheikh; Ayaz
• Assistant Examiner(s): HALIYUR, VENKATESH N
• Application Number:
  US12/615,142
• Publication Number:
  US 20100046556A1
• Time in Patent Office: 631 Days
• Field of Search: 370216-503, 709230-236
• US Class Current: 370/229
• CPC Class Codes: G06F 15/17368 non hierarchical topologies
• CPC Class Codes: H04L 12/2852 Metropolitan area networks
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types

Abstract

Solutions are provided that allow a network device to apply flow control on the MAC layer while taking into account the priority of the frame of traffic. This may be accomplished by generating a frame indicating that traffic flow should be paused, while utilizing a new opcode value, or alternatively by utilizing a new type/length value (possibly combined with a new opcode value). A receiving device may then examine the fields of the frame to determine whether it should use priority-based pausing, and then examine other fields to determine which priority-levels to pause and for how long. This allows for improved efficiency in flow control on the MAC layer.

Claims

1. A method comprising:

determining, in a network device, a present need to pause traffic flow to the network device, and if a present need to pause traffic flow to the network device is determined, placing in a first field in a frame, a value signifying that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device;

placing in a priority mask field of the frame, a value signifying which priority levels should be paused; and

placing in a second field in the frame, a value signifying that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a third field.

2. The method of claim 1, further comprising:

placing in the third field, a separate value for each possible priority level, the separate value indicating an independent pause time for each corresponding priority level.

3. The method of claim 2, wherein the third field is equal in size to the third field in a standard PAUSE frame multiplied by the number of possible priorities.

4. The method of claim 1, wherein the frame is a PAUSE frame.

5. The method of claim 1, wherein the value signifying that traffic flow to the network device should be paused or not paused according to its priority level is a value not used by standard PAUSE frames in the first field.

6. The method of claim 2 wherein

the first field comprises a type/length field;

the second field comprises an opcode field; and

the third field comprises a pause time field.

18. The method of claim 1, further comprising creating the priority mask field before the placing.

20. The method of claim 1 wherein the first field comprises a type/length field.

7. A method comprising:

examining, in a network device, a value in a first field in a frame to determine if it signifies that the frame indicates that traffic flow to the network device should be paused and if it signifies that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device;

pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame if the value in the first field signified that traffic flow to a network device should be paused and that traffic flow to the network device should be paused or not paused according to its priority level;

examining a value in the first field to determine if it also signifies that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a pause time;

wherein the pausing traffic flow further comprises pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame for time periods indicated by time periods corresponding to each priority level in a third field in the frame if the first field signifies that the pausing will be for times corresponding to each priority level indicated by a pause time.

8. The method of claim 7, wherein the times are a separate value for each possible priority level indicating an independent pause time for each corresponding priority level.

9. The method of claim 7 wherein

the first field comprises a type/length field;

the second field comprises an opcode field; and

the third field comprises a pause time field.

21. The method of claim 7 wherein the first field comprises a type/length field.

10. An apparatus comprising:

a priority level based pause traffic flow value-to-first field placer configured to, if a present need to pause traffic flow to a network device is determined, place in a first field in a frame, a value signifying that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device; and

a paused priority level value-to-priority mask field placer configured to place in a priority mask field in the frame, a value signifying which priority levels should be paused;

wherein the apparatus is further configured to place in a second field in the frame, a value signifying that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a third field.

11. The apparatus of claim 10, further comprising:

a priority level separate value-to-third field placer coupled to the pause times corresponding to priority level value-to-second field placer and configured to place in the third field, a separate value for each possible priority level, the separate value indicating an independent pause time for each corresponding priority level.

12. The apparatus of claim 10 wherein

the first field comprises a type/length field;

the second field comprises an opcode field; and

the third field comprises a pause time field.

19. The apparatus of claim 10, further comprising a priority mask field creator coupled to the priority level based pause traffic flow value-to-first field placer and configured to create a priority mask field in the frame.

22. The apparatus of claim 10 wherein the first field comprises a type/length field.

13. An apparatus comprising:

a first field value examiner configured to examine a value in a first field in a frame to determine if it signifies that the frame indicates that traffic flow to a network device should be paused and if it signifies that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device; and

a priority level traffic flow pauser coupled to the first field value examiner and configured to pause traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame if the value in the first field signified that traffic flow to a network device should be paused and that traffic flow to the network device should be paused or not paused according to its priority level;

wherein the apparatus is further configured to place in a second field in the frame, a value signifying that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a third field.

14. An apparatus comprising:

means for determining a present need to pause traffic flow to a network device, and if a present need to pause traffic flow to a network device is determined, placing in a first field in a frame, a value signifying that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device;

means for placing in a priority mask field of the frame, a value signifying which priority levels should be paused; and

means for placing in a second field in the frame, a value signifying that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a third field.

15. An apparatus comprising:

means for examining a value in a first field in a frame to determine if it signifies that the frame indicates that traffic flow to a network device should be paused and if it signifies that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device; and

means for pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame if the value in the first field signified that traffic flow to the network device should be paused and that traffic flow to the network device should be paused or not paused according to its priority level; and

means for examining a value in the first field to determine if it also signifies that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a pause time;

wherein the pausing traffic flow further comprises pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame for time periods indicated by a times corresponding to each priority level in a third field in the frame if the first field signifies that the pausing will be for times corresponding to each priority level indicated by a pause time.

16. A non-transitory computer program storage device readable by a computer, tangibly embodying a computer program of instructions executable by the computer to perform a method, the method comprising:

determining, in a network device, a present need to pause traffic flow to the network device, and if a present need to pause traffic flow to a network device is determined, placing in a first field in a frame, a value signifying that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device;

placing in a priority mask field of the frame, a value signifying which priority levels should be paused; and

placing in a second field in the frame, a value signifying that the pausing will be for time periods indicated by times corresponding to each priority level by a third field.

17. A non-transitory computer program storage device readable by a computer, tangibly embodying a computer program of instructions executable by the computer to perform a method, the method comprising:

examining, in a network device, a value in a first field in a frame to determine if it signifies that the frame indicates that traffic flow to the network device should be paused and if it signifies that traffic flow to the network device should be paused or not paused according to its priority level, the traffic flow comprising one or more packets, including a priority level, the priority level indicating a relative level of importance of timely delivery of the packet to the network device;

pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame if the value in the first field signified that traffic flow to a network device should be paused and that traffic flow to the network device should be paused or not paused according to its priority level; and

examining a value in the first field to determine if it also signifies that the pausing will be for time periods indicated by times corresponding to each priority level indicated by a pause time;

wherein the pausing traffic flow further comprises pausing traffic flow to the network device with priority levels corresponding to levels signified by a value in a priority mask field in the frame for time periods indicated by a times corresponding to each priority level in a third field in the frame if the first field signifies that the pausing will be for times corresponding to each priority level indicated by a pause time.