Policing Networks

• US 20080192636A1
• Filed: 02/07/2006
• Published: 08/14/2008
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Salvatori, Alessandro, Briscoe, Robert J., Jacquet, Arnaud, Di Cairano-Gilfedder, C
• Granted Patent: US 7,948,878 B2
• Time in Patent Office: Days
• US Class Current: 370/236
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/18 End to end
• CPC Class Codes: H04L 47/20 Traffic policing
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 47/2425 for supporting services specification, e.g. SLA
• CPC Class Codes: H04L 47/283 in response to processing delays, e.g. caused by jitter or round trip time [RTT]
• CPC Class Codes: H04L 47/31 by tagging of packets, e.g. using discard eligibility [DE] bits
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames

Abstract

Methods and apparatus for policing flow in a data network by determining a measure of greediness of a flow through a node, comparing said measure of greediness with a measure indicative of acceptable greediness dependent on the expected greediness of a compliant flow experiencing substantially similar path conditions, and designating the flow for possible sanction in the event that the greediness is not in accordance with said acceptable greediness. Such methods and apparatus allow for the policing of a data network wherein one or more fields in a data packet that carry information relating to a characterisation of an end-to-end path and/or a downstream path of said data packet are used in order to police said data network.

Claims

1. A method of policing flow in a data network, said data network providing a network service having an associated reference rate adaptation policy, said method comprising steps of:

determining a measure of greediness of a flow through a node;

comparing said measure of greediness with a measure indicative of acceptable greediness; and

designating the flow for possible sanction in the event that the greediness is not in accordance with the acceptable greediness;

characterised in that said measure indicative of acceptable greediness is determined in dependence on the expected greediness of a flow conforming to the reference rate adaptation policy associated with said network service and experiencing substantially similar path conditions.

2. A method according to claim 1 wherein the flow comprises a plurality of messages.

3. A method according to claim 2 wherein said messages are data packets.

4. A method according to claim 2 wherein said messages carry information indicative of one or more characteristics of a path used by the messages in traversing a data network.

5. A method according to claim 4 wherein said messages carry information indicative of a characteristic of an end-to-end path in said data network.

6. A method according to claim 4 wherein said messages carry information indicative of a characteristic of a downstream path in said data network.

7. A method according to claim 4 wherein said messages carry information indicative of congestion.

8. A method according to claim 4 wherein said messages carry information indicative of a round-trip time (RTT) for messages traversing said path in said data network.

9. A method according to claim 2, further comprising a step of selecting one or more messages from said flow, wherein said step of comparing is performed in relation to said selected messages.

10. A method according to claim 9 wherein the probability of a particular message being selected from said flow is dependent on the greediness of said flow

11. A method according to claim 1, wherein said measure of greediness is determined in dependence on a rate adaptation policy of said flow.

12. A method according to claim 1, wherein said expected greediness is determined with reference to a measure of greediness of a TCP-compliant flow.

13. A method according to claim 1, wherein said measure indicative of acceptable greediness is determined with reference to a desired level of robustness of a node when performing the method.

14. A method according to claim 1, wherein said measure indicative of acceptable greediness is determined with reference to a desired level of responsiveness of a node when performing the method.

15. A method according to claim 1, wherein said measure indicative of acceptable greediness is determined with reference to state requirements of a node when performing the method.

16. A method according to claim 1, wherein said step of designating the flow for possible sanction is taken in the event that the greediness of the flow passes a threshold level of acceptable greediness.

17. A method according to claim 1, wherein the likelihood of said step of designating a flow for possible sanction being taken is dependent on a measure of disparity between said greediness and said acceptable greediness.

18. A method according to claim 1, wherein the severity of any possible sanction for which a flow is designated is dependent on a measure of disparity between said greediness and said acceptable greediness.

19. A method according to claim 1, further comprising a step of taking action in relation to flows designated for possible sanction.

20. A method according to claim 19 wherein said action comprises dropping one or more messages from one or more flows designated for possible sanction.

21. A method according to claim 19 wherein said action comprises demoting one or more messages from one or more flows designated for possible sanction to a traffic class having a lower priority.

22. A method according to claim 19 wherein said action comprises marking one or more messages from one or more flows designated for possible sanction.

23. A method according to claim 22 wherein said action of marking comprises marking messages with a notification to a source of said flows indicating that further sanction may be taken in the event that said source fails to react appropriately to said marking.

24. A method according to claim 19 wherein said action comprises delaying one or more subsequent messages from one or more flows designated for possible sanction.

25. A method according to claim 19 wherein said action comprises subjecting one or more flows designated for possible sanction to rate control.

26. A method according to claim 1 wherein said measure indicative of acceptable greediness in respect of a flow may be varied in dependence on a measure of past behaviour in respect of said flow.

27. A method according to claim 1 wherein the severity and/or likelihood of any possible sanction in respect of a flow may be varied in dependence on a measure of past behaviour in respect of said flow.

28. A method according to claim 1 wherein said measure indicative of acceptable greediness and/or said expected greediness in respect of a flow may be varied in dependence on a class of traffic of said flow.

29. Apparatus for policing flow in a data network, said apparatus comprising means for carrying out the steps for implementing methods according to claim 1.