Method to regulate traffic congestion in a network

• US 20050052994A1
• Filed: 09/04/2003
• Published: 03/10/2005
• Est. Priority Date: 09/04/2003
• Status: Active Grant

• Current Assignee: HTC Corporation
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Lee, Man-Ho Lawrence
• Granted Patent: US 7,508,763 B2
• Time in Patent Office: Days
• US Class Current: 370/230
• 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 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/39 Credit based

Abstract

A method and system for controlling traffic on a network. A congestion indicator is generated by network components in response to the flow of network traffic. The congestion indicator is received by a network peripheral node that has a threshold variable which controls the flow of traffic flowing from the network peripheral node. The threshold variable corresponding to the congestion indicator will be reduced in order to restrict the flow of traffic flowing from that network peripheral node. If more than one congestion indicator is received by the network peripheral node, then the threshold variable will continue to be reduced thereby further restricting network traffic. If no further congestion indicators are received, then the network peripheral node will terminate the Back-Off Period state of the threshold variable such that the threshold variable can then be increased and network traffic can increase.

Claims

14. A system for regulating traffic in a network having a plurality of components and peripheral nodes, the traffic being created as the network peripheral nodes exchange data and consume network resources, the system comprising:

means for generating at least one congestion indicator at a network component responsive to an indication of traffic congestion in the network;

at least one network peripheral node responsive to the congestion indicator, wherein a threshold variable associated with the received congestion indicator is used to define a maximum amount of a specified type of network resources to be allocated for a use associated with the receiving network peripheral node including,

a Feedback Mechanism configured to initiate a Back-Off Period at the receiving network node in response to receiving the congestion indicator, and performing a back off process by,

initiating a back off time interval,

if an additional valid congestion indicator associated with the threshold variable has been received within the back off time interval, adjusting the value of the threshold variable to reduce the maximum amount, and resetting the back off time interval, and

if no additional valid congestion indicator associated with the threshold variable has been received within the back off time interval, adjusting the value of the threshold variable to increase the maximum amount, and terminating the Back-Off Period;

a Slow Advance Mechanism configured to adjust the value of the threshold variable to increase the maximum amount whenever the Back-Off Period is not active; and

means for controlling the flow of traffic across the network based at least in part on the value of the threshold variable.

1. A method of regulating traffic congestion in a network, the congestion being created as peripheral nodes of the network consume network resources, the method comprising the steps of:

generating at least one congestion indicator at an inner network component responsive to an indication of traffic congestion in such network component;

receiving the congestion indicator at one or more network peripheral nodes, wherein a threshold variable associated with the received congestion indicator is used to define a maximum amount of a specified type of network resources to be allocated for a particular use;

initiating a Back-Off Period at the component in response to receiving the congestion indicator, and performing a back off process by,

initiating a back off time interval,

if an additional valid congestion indicator associated with the threshold variable has been received within the back off time interval, adjusting the value of the threshold variable to reduce the maximum amount, and resetting the back off time interval, and

if no additional valid congestion indicator associated with the threshold variable has been received within the back off time interval, adjusting the value of the threshold variable to increase the maximum amount, and terminating the Back-Off Period;

whenever the Back-Off Period is not active, performing a Slow Advance process that includes adjusting the value of the threshold variable to increase the maximum amount; and

controlling consumption of the specified type of network resources based at least in part on the value of the threshold variable.

2. A method of regulating traffic as recited in claim 1 wherein the step of terminating the Back-Off Period further includes:

comparing a current value of the threshold variable to an initial value of the threshold variable; and

if the current value is greater than the initial of the threshold variable, terminating the Back-Off Period.

3. A method of regulating traffic as recited in claim 1 wherein the back off process further includes:

recording an initial value of the threshold variable as a value of a Last Known Good Threshold Variable; and

limiting the allocation of the specified type of network resources to a level defined by a current threshold variable value below the Last Known Good Threshold Variable during the Back-Off Period.

4. A method of regulating traffic as recited in claim 3 wherein the step of terminating the Back-Off Period includes:

comparing the current value of the threshold variable to the current value of the Last Known Good Threshold Variable; and

terminating the Back-Off Period if the current value of the threshold variable is greater than or equal to the current value of the Last Known Good Threshold Variable.

5. A method of regulating traffic as recited in claim 4 wherein the back off process further includes a step of decaying the value of the Last Known Good Threshold Variable during the back off time period.

6. A method of regulating traffic as recited in claim 4 wherein the back off process further includes:

if an additional valid congestion indicator associated with the threshold variable has been received within the back off time interval,

determining if the additional valid congestion indicator is a valid congestion indicator received since the initiation of the back off time interval, and

if the additional congestion indicator is a valid congestion indicator received since the initiation of the back off time interval, further adjusting the value of the threshold variable to reduce the maximum amount.

7. A method of regulating traffic as recited in claim 4 wherein the back off process further includes:

comparing a current value of the threshold variable to a minimum threshold value following the step of adjusting the value of the threshold variable to reduce the maximum amount; and

if the current value of the threshold variable is less than the minimum threshold value, setting the value of the threshold variable equal to the value of the minimum threshold variable.

8. A method of regulating traffic as recited in claim 1 wherein the step of adjusting the value of the threshold variable to reduce the maximum amount includes adjusting the value of the threshold variable by a specified percentage of the current value of the threshold variable.

9. A method of regulating traffic as recited in claim 8 wherein the specified percentage is an attribute of the received congestion indicator.

10. A method of regulating traffic as recited in claim 1 wherein the Slow Advance process further includes:

initiating a Slow Advance time interval;

determining a currently demanded amount of the specified type of network resources that is currently being used;

comparing the currently demanded amount to the maximum amount of the specified type of resources allocated as indicated by a current value of the threshold variable; and

if the currently demanded amount is greater than or equal to the maximum amount of resources allocated, and the Slow Advance interval has expired, adjusting the value of the threshold variable to increase the maximum amount.

11. A method of regulating traffic as recited in claim 10 wherein the step of adjusting the value of the threshold variable to increase the maximum amount includes adjusting the value of the threshold variable by a specified unit value.

12. A method of regulating traffic as recited in claim 1 wherein the threshold variable is used to define a maximum amount of traffic credit issued to other components in the network.

13. A method of regulating traffic as recited in claim 10 further comprising:

further adjusting the value of the threshold variable to further increase the maximum amount during the Slow Advance Interval if the currently demanded amount is greater than the maximum amount of resources allocated while the network component is not in the Back-Off Period.

15. A system as recited in claim 14 wherein the means for controlling the flow of traffic includes a transport control mechanism.

16. A system as recited in claim 14 wherein the Feedback Mechanism is further configured to:

compare a current value of the threshold variable to an initial value of the threshold variable; and

if the current value is greater than the initial of the threshold variable, terminate the Back-Off Period.

17. A system as recited in claim 14 wherein the Feedback Mechanism is further configured to:

record an initial value of the threshold variable as a value of a Last Known Good Threshold Variable during the back off process; and

limit the allocation of the specified type of network resources to a level below a level defined by the value of the current threshold variable below the Last Known Good Threshold Variable during the Back-Off Period.

18. A system as recited in claim 17 wherein the Feedback Mechanism is further configured to:

compare the current value of the threshold variable to the current value of the Last Known Good Threshold Variable; and

terminate the Back-Off Period if the current value of the threshold variable is greater than or equal to the current value of the Last Known Good Threshold Variable.

19. A system as recited in claim 17 wherein the Feedback Mechanism is further configured:

if an additional valid congestion indicator associated with the threshold variable has been received within the back off time interval,

to determine if the additional valid congestion indicator is a first valid congestion indicator received since the initiation of the back off time interval, and

if the congestion indicator is a first valid congestion indicator received since the last Back-Off Period, to set the value of the threshold variable equal to the current value of the Last Known Good Threshold Variable.

20. A system as recited in claim 17 wherein the Feedback Mechanism is further configured to:

compare a current value of the threshold variable to a minimum threshold value following the step of reducing the value of the threshold variable; and

if the current value of the threshold variable is less than the minimum threshold value, set the value of the threshold variable equal to the value of the minimum threshold variable.

21. A system as recited in claim 14 wherein the Feedback Mechanism adjusts the value of the threshold variable to reduce the maximum amount by a specified percentage.

22. A system as recited in claim 21 wherein the specified percentage is an attribute of the received congestion indicator.

23. A system as recited in claim 14 wherein the Slow Advance Mechanism is configured to:

initiate a Slow Advance Timer;

determine a currently demanded amount of the specified type of network resources that is currently being used;

compare the currently demanded amount to the maximum amount of the specified type of resources allocated as indicated by a current value of the threshold variable; and

if the currently demanded amount is greater than or equal to the maximum amount of resources allocated, and the Slow Advance timer has expired, adjust the value of the threshold variable to increase the maximum amount.

24. A system as recited in claim 23 wherein the Slow Advance Mechanism is configured to adjust the value of the threshold variable to increase the maximum amount by a specified fixed value.

25. A system as recited in claim 14 wherein the threshold variable is used to define a maximum amount of traffic credit issued to other peripheral nodes in the network.

26. A system as recited in claim 23 wherein the Slow Advance Mechanism is configured to further adjust the value of the threshold variable to further increase the maximum amount during the Slow Advance Interval if the currently demanded amount is greater than the maximum amount of resources allocated while the threshold variable associated with the resource and network peripheral node is not in the Back-Off Period.

18-1. A system as recited in claim 17 wherein the Feedback Mechanism is further configured to decay the value of the Last Known Good Threshold Variable during the back off time period.

27. A method of regulating traffic in a network including a plurality of inner network components and peripheral nodes, the traffic being created as peripheral nodes consume network resources, the method comprising:

generating at least one congestion indicator at an inner network component;

receiving the congestion indicator at one or more network nodes, wherein a threshold variable associated with the received congestion indicator is used to define a maximum amount of a specified type of network resources to be allocated for a particular use;

initiating a Back-Off Period at the component in response to receiving the congestion indicator, and adjusting the value of the threshold variable to reduce the maximum amount of the specified type of network resources to be allocated for the particular use;

whenever the threshold variable is not in a backed off state, performing a Slow Advance process that includes adjusting the value of the threshold variable to increase the maximum amount of the specified type of network resources to be allocated for the particular use; and

controlling consumption of the specified type of network resources based at least in part on the value of the threshold variable.

28. A computer readable medium embodying program instructions for regulating traffic in a network including a plurality of inner network components and peripheral nodes, the traffic being created as peripheral nodes consume network resources, comprising:

code segments for generating at least one congestion indicator at one or more inner network components;

code segments for receiving the congestion indicator at one or more network nodes, wherein a threshold variable associated with the received congestion indicator is used to define a maximum amount of a specified type of network resources to be allocated for a particular use;

code segments for initiating a Back-Off Period at the component in response to receiving the congestion indicator, and adjusting the value of the threshold variable to reduce the maximum amount of the specified type of network resources to be allocated for the particular use;

code segments for, whenever the Back-Off Period associated with the threshold variable is not active, performing a Slow Advance process that includes adjusting the value of the threshold variable to increase the maximum amount of the specified type of network resources to be allocated for the particular use; and

code segments for controlling consumption of the specified type of network resources based at least in part on the value of the threshold variable.