Method and system for flow management with scheduling

• US 20060088032A1
• Filed: 10/26/2005
• Published: 04/27/2006
• Est. Priority Date: 10/26/2004
• Status: Abandoned Application

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Venables, Bradley
• Application Number:
  US11/258,101
• Publication Number:
  US 20060088032A1
• Time in Patent Office: Days
• US Class Current: 370/395.400
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/22 Traffic shaping
• 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

Abstract

Method and System for flow management with scheduling is provided. The system includes a traffic shaper/scheduler, a system monitor, and a modification amount register (MAR) module. The traffic shaper/scheduler implements scheduling algorithm to arbitrate between flows. The system monitor monitors the flows and generates modification request for a target flow to update the MAR. The MAR may be consumed by the scheduling algorithm when the flow associated with the MAR is selected in a scheduling event.

Claims

1. A system for data transmission, comprising:

a scheduler for implementing scheduling to select a data flow for transmission;

a system monitor for determining one or more than one target flow and a modification amount for each target flow; and

a modification amount register for holding the total modification amount for each target flow as the system monitor requests modification and the scheduler consumes the modification,

the scheduler being configured with the transmission characteristics of each flow including the one or more than one target flow, to select the transmission order of flows independently of the modification amount register, and being capable of altering the transmission characteristics of a selected flow which is a target flow, based on the modification amount stored in the modification amount register of the target flow.

2. A system according to claim 1, wherein the scheduler applies the modification amount for the target flow to the selected flow when the scheduler selects the target flow for the transmission, and consumes the modification amount stored in the modification amount register of the target flow.

3. A system according to claim 2, wherein the scheduler is capable of consuming at least part of the contents of the modification amount register in a scheduling event, the remainder of the modification amount being in the modification amount register for a subsequent scheduling event.

4. A system according to claim 2, wherein the scheduler includes a rate scheduler where the modification amount effects a change in rate in a manner similar to that of a change in length of the packet in the current scheduling event,

5. A system according to claim 4, wherein the modification amount register has enough resolution to accommodate modification amounts of the same magnitude as the maximum transmission unit of the target flow.

6. A system according to claim 2, wherein the scheduler includes a weighted fair scheduler where the modification amount effects a change in remaining weight or deficit in weight in a manner similar to that of a change in length of the packet in the current scheduling event.

7. A system according to claim 1, wherein the system monitor provides flow coupling by applying the amount of data sent by one or more flows to the modification amount register of the target flow.

8. A system according to claim 7, wherein the system monitor uses an identifier of the one or more flows to calculate or lookup the identifier of the target flow.

9. A system according to claim 8, wherein the one or more flows and the target flow represent a customer, and the scheduling behavior for the target flow represents the overall customer fairness or rate limit.

10. A system according to claim 9, wherein the target flow is configured with a rate limit which is at least as large as the rate achieved by all of the one or more flows coupled into the target flow.

11. A system according to claim 9, wherein the target flow is configured with a rate limit which is at least twice as large as the rate achieved by all of the one or more flows coupled into the target flow and the modification amount register is dimensioned to accommodate at least as much data as the maximum transmission unit of the customer.

12. A system according to claim 9, wherein the one or more flows being coupled into the target flow represent jitter sensitive data, and the target flow represents the rest of the customer data which is less jitter sensitive.

13. A system according to claim 12, wherein the one or more flows being coupled into the target flow include voice packets.

14. A system according to claim 1, wherein the system monitor provides flow control by applying a modification amount corresponding to excess data in a downstream resource to a flow that feeds the downstream resource

15. A system according to claim 1, wherein the system monitor provides correction of frame length by observing downstream changes to the frame length and applying the change in length to the modification amount register for the same flow.

16. A system according to claim 11, wherein the system monitor calculates the modification amount as the difference between the scheduler'"'"'s assumed frame length and the actual observed frame length.

17. A system according to claim 1, wherein the modification amount register includes an update circuit for communicating with the system monitor and updating the modification amount register.

18. A system according to claim 13 wherein the update circuit is capable of adding to or subtracting from the existing modification amount based on information received from the scheduler or the system monitor

19. A system according to claim 17, wherein the update circuit provides to the scheduler the current value of the modification amount register for the selected flow.

20. A system according to claim 17, wherein the update circuit implements resolving conflicts in updating the modification amount register when the scheduler and the system monitor request a change to the same flow.

21. A system according to claim 2, wherein the modification amount register includes an amount of data to increase the target flow by, an amount of data to decrease the target flow by, or both.

22. A method for data transmission, comprising the steps of:

at a scheduler, implementing scheduling to select a data flow for transmission;

determining one or more than one target flow for an application and a modification amount for each target flow, and generating a modification request associated with the modification amount, independently of the scheduling, and

updating a modification amount register for each target flow based on the modification request, independently of the scheduling, to modify the behavior of the scheduler using the modification amount register of a target flow when the scheduler selects the target flow for the transmission.

23. A method according to claim 22, wherein the application is for a flow coupling, and further comprising the step of:

modifying the behavior of the scheduler by applying the amount of data sent by one or more flows to the modification amount register of the target flow.

24. A method according to claim 23, wherein the application is for a flow control, and further comprising the step of:

modifying the behavior of the scheduler by applying a modification amount corresponding to excess data in a downstream resource to a flow that feeds the downstream resource.

25. A method according to claim 23, wherein the application is for correction of frame length, and further comprising the step of:

modifying the behavior of the scheduler by applying a modification amount corresponding to observed downstream changes to the frame length for the same flow.

26. A method according to claim 23, further comprising the step of:

at the scheduler, consuming the modification amount stored in the modification amount register of the target flow when the scheduler selects the target flow for the transmission.