Traffic management in packet-based networks

• US 20030007454A1
• Filed: 07/09/2001
• Published: 01/09/2003
• Est. Priority Date: 07/09/2001
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shorey, Rajeev
• Granted Patent: US 6,958,998 B2
• Time in Patent Office: Days
• US Class Current: 370/229
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/125 by balancing the load, e.g. traffic engineering
• CPC Class Codes: H04L 47/20 Traffic policing
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 47/2458 Modification of priorities while in transit
• 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 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• 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

Providing packet-based service differentiation on packet-based networks involves first determining information associated with packets as a basis for inferring connection characteristics associated with the respective packet, as the packets pass though a particular network node. Statistical measures based on numerical values of, for example, Round Trip Time (RTT), is used to characterize connections as being, in this case “long” or “short”. “Long” connections are given a higher priority than “short” connections. Accordingly, the assigned priority associated with particular packets can be used to adjust drop probabilities for those packets.

Claims

1. A method of handling packet traffic on a packet-based network, the method comprising the steps of:

receiving, at a network node, a flow of packets from the packet-based network;

determining, for each of the received packets, a metric at least partly based on the duration of transmission for the received packet;

assigning, to each of the packets, a relative service priority on the basis of the metric; and

queuing one or more of the packets in a queue and transmitting the queued packets from the network node.

2. The method as claimed in claim 1, further comprising the step of:

calculating one or more statistical measures associated with values of said metric for the received packets, for use in the step of assigning a relative service priority.

3. The method as claimed in claim 1, further comprising the step of:

preferentially dropping packets that have a lower relative service priority in favour of packets that have a greater relative service priority, prior to the step of queuing one or more of the packets.

4. The method as claimed in claim 1, further comprising the step of:

marking packets that have a lower relative service priority, prior to the step of queuing one or more of the packets.

5. The method as claimed in claim 1, further comprising the step of:

dynamically allocating a packet drop probability for one or more of the packets, based on the assigned relative service priority for the respective packets, prior to the step of queuing one or more packets, wherein packets with a higher relative service priority are allocated a lower packet drop probability and packets with a lower relative service priority are allocated a higher packet drop probability.

6. The method as claimed in claim 5, wherein said step of dynamically allocating a packet drop probability is preformed if an average number of queued packets, at the network node, falls between maximum and minimum predetermined thresholds.

7. The method as claimed in claim 6, further comprising the step of:

dropping packets if an average number of queued packets, at the network node, exceeds the maximum predetermined threshold.

8. The method as claimed in claim 6, further comprising the step of:

admitting packets if an average number of queued packets, at the network node, falls below the minimum predetermined threshold.

9. The method as claimed in claim 1, wherein said metric is the value of time taken by the packet to traverse the network from the source to destination, and the packet'"'"'s corresponding acknowledgment to traverse the network from the destination to source.

10. The method as claimed in claim 1, wherein said metric incorporates a hopcount representative of the number of nodes traversed by the packet from source of the packet to the network node.

11. The method as claimed in claim 2, wherein the statistical measures include average value.

12. The method as claimed in claim 11, wherein the statistical measures further include maximum value and minimum value.

13. The method as claimed in claim 11, wherein two classes of relative service priority, comprising a higher relative service priority and a lower relative service priority, are assigned to the received packets depending on a comparison of the metric with its corresponding average value for the received packets.

14. The method as claimed in claim 1, wherein the packet-based network transmits internet protocol (IP) packets.

15. The method as claimed in claim 14, wherein the packet-based network uses the transmission connection protocol (TCP).

16. The method as claimed in claim 15, wherein the metric is the value of the round trip time (RTT) field in the TCP packet header.

18. The method as claimed in claim 16, further comprising the step of:

preferentially dropping packets that have a lower relative service priority in favour of packets that have a greater relative service priority, prior to the step of queuing one or more of the packets.

19. The method as claimed in claim 18, further comprising the step of:

marking packets that have a lower relative service priority, prior to the step of queuing one or more of the packets.

20. The method as claimed in claim 17, further comprising the step of:

dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority, prior to the step of queuing one or more of the packets, wherein packets with a higher relative service priority are allocated a lower packet drop probability and packets with a lower relative service priority are allocated a higher packet drop probability.

21. The method as claimed in claim 20, wherein said step of dynamically allocating a packet drop probability is preformed if an average number of queued packets, at the network node, falls between maximum and minimum predetermined thresholds.

22. The method as claimed in claim 21, further comprising the step of:

dropping packets if an average number of queued packets, at the network node, exceeds the maximum predetermined threshold.

23. The method as claimed in claim 21, further comprising the step of:

admitting packets if an average number of queued packets, at the network node, falls below the minimum predetermined threshold.

24. The method as claimed in claim 20, wherein a plurality of different classes of relative service priority are available to be assigned to the received packets depending upon the identity of the connection characteristic for respective packets.

25. The method as claimed in claim 17, wherein the packet-based network transmits internet protocol (IP) packets.

26. The method as claimed in claim 17, wherein the packet-based network uses the transmission connection protocol (TCP).

17. A method of handling packet traffic on a packet-based network, the method comprising steps of:

receiving, at a network node, a flow of packets from the packet-based network;

inferring, for each of the received packets, a connection characteristic at least partly representative of the duration of transmission for the received packet;

assigning, to each of the packets, a relative service priority on the basis of the inferred connection characteristic; and

queuing one or more of the packets in a queue and transmitting the queued packets from the network node.

27. A network node apparatus for handling packet traffic on a packet-based network, said apparatus including:

means for receiving, at a network node, a flow of packets from the packet-based network;

means for determining, for each of the received packets, a metric at least partly based the duration of transmission for the received packet;

means for comparing, for each of the received packets, said metric with a corresponding reference value;

means for assigning, to each of the packets, a relative service priority on the basis of the comparison;

means for queuing one or more of the packets in a queue and transmitting the queued packets from the network node.

28. A network node apparatus for handling packet traffic on a packet-based network, said apparatus including:

means for receiving, at a network node, a flow of packets from the packet-based network;

means for inferring, for each of the received packets, a connection characteristic at least partly representative of the duration of transmission for the received packet;

means for assigning, to each of the packets, a relative service priority on the basis of the inferred connection characteristic; and

means for queuing one or more of the packets in a queue and transmitting the queued packets from the network node.

29. A computer software program, recorded on a medium and capable of execution by computing means able to interpret the computer software program, for handling packet traffic on a packet-based network, said computer software program comprising:

code means for receiving, at a network node, a flow of packets from the packet-based network;

code means for determining, for each of the received packets, a metric at least partly based the duration of transmission for the received packet;

code means for comparing, for each of the received packets, said metric with a corresponding reference value;

code means for assigning, to each of the packets, a relative service priority on the basis of the comparison; and

code means for queuing one or more of the packets in a queue and transmitting the queued packets from the network node.

30. A computer software program, recorded on a medium and capable of execution by computing means able to interpret the computer software program, for handling packet traffic on a packet-based network, said computer software program comprising:

code means for receiving, at a network node, a flow of packets from the packet-based network;

code means for inferring, for each of the received packets, a connection characteristic at least partly representative of the duration of transmission for the received packet;

code means for assigning, to each of the packets, a relative service priority on the basis of the inferred connection characteristic; and

code means for queuing one or more of the packets in a queue and transmitting the queued packets from the network node.