Traffic management in packet-based networks

• US 6,958,998 B2
• Filed: 07/09/2001
• Issued: 10/25/2005
• Est. Priority Date: 07/09/2001
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shorey, Rajeev
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): PHAM, BRENDA H
• Application Number:
  US09/901,229
• Publication Number:
  US 20030007454A1
• Time in Patent Office: 1,569 Days
• Field of Search: 370/229, 370/230, 370/235, 370/253, 370/349, 370/386, 370/389, 370/396, 370/413, 370/395.21, 370/395.41, 370/395.43, 370/428, 370/252, 370/412, 370/395.4, 370/395.42, 370/429
• US Class Current: 370/395.42
• 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:

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;

calculating one or more statistical measures associated with values of said metric for the received packets, wherein the statistical measures include an average value;

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 dynamically allocating a packet drop probability for one or more of the packets, based on the assigned relative service priority for the respective packets.

2. The method as claimed in claim 1, further comprising preferentially dropping packets that have a lower relative service priority in favor of packets that have a greater relative service priority, prior to the step of queuing of one or more of the packets.

3. The method as claimed in claim 1, further comprising marking packets that have a lower relative service priority, prior to the queuing of one or more of the packets.

4. The method as claimed in claim 1, further comprising dynamically allocating a packet drop probability occurs, prior to the queuing of 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.

5. The method as claimed in claim 4, wherein said dynamically allocating a packet drop probability is preformed if an avenge number of queued packets, at the network node, falls between maximum and minimum predetermined thresholds.

6. The method as claimed in claim 5, further comprising dropping packets if an average number of queued packets, at the network node, exceeds the maximum predetermined threshold.

7. The method as claimed in claim 5, further comprising admitting packets if an average number of queued packets, at the network node, falls below the minimum predetermined threshold.

8. The method as claimed in claim 1, wherein said metric comprises 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.

9. 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.

10. The method as claimed in claim 9, wherein the statistical measures further include a maximum value and a minimum value.

11. The method as claimed in claim 9, 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.

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

13. The method as claimed in claim 12, wherein the packet-based network uses the transmission connection protocol (TCP).

14. The method as claimed in claim 13, wherein the metric comprises the value at the round trip time (RTT) field in the TCP packet header.

15. 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;

dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority; and

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

16. The method as claimed in claim 15, further comprising preferentially dropping packets that have a lower relative service priority in favor of packets that have a greater relative service priority, prior to the queuing of one or more of the packets.

17. The method as claimed in claim 16, further comprising marking packets that have a lower relative service priority, prior to the queuing of one or more of the packets.

18. The method as claimed in claim 15, 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.

19. The method as claimed in claim 18, wherein said 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.

20. The method as claimed in claim 19, further comprising dropping packets if an average number of queued packets, at the network node, exceeds the maximum predetermined threshold.

21. The method as claimed in claim 19, further comprising admitting packets if an average number of queued packets, at the network node, falls below the minimum predetermined threshold.

22. The method as claimed in claim 18, 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 fir respective packets.

23. The method as claimed in claim 15, wherein the packet-based network transmits internet protocol (IP) packets.

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

25. 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 dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority; and

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

26. 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;

means for dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority; and

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

27. 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;

code means for dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority; and

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

28. 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;

code means for dynamically allocating a packet drop probability for one or more of the packets, based on the results of the assigned relative service priority; and

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