Real-time bandwidth provisioning in a switching device

• US 7,631,096 B1
• Filed: 10/14/2003
• Issued: 12/08/2009
• Est. Priority Date: 10/11/2002
• Status: Expired due to Fees

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Weaver, Dennis, Yeh, Chiang
• Primary Examiner(s): Chang; Jungwon
• Application Number:
  US10/684,772
• Time in Patent Office: 2,247 Days
• Field of Search: 370/229, 370/250, 370/509, 370/414, 370/252, 370/231, 709/222, 709/235, 709/232, 709/224, 455/422, 702/186
• US Class Current: 709/235
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]

Abstract

A method and apparatus for provisioning bandwidth among a plurality of queues in a switching device are disclosed. The bandwidth provisioning employs a QoS label with a timestamp to determine the queue delay associated with the transmission of the packet from an ingress switching device, e.g. ingress blade, to an egress switching device, e.g. egress blade. The QoS label is applied on the ingress blade and removed and read on the egress blade. Using the timestamp, the switch can identify congested priority queues at the ingress blade and selectively enable fragmentation for purposes of preventing particular packets and or particular flows from consuming disproportionately large system resources including bandwidth necessary to communicate packets through the switch fabric. Some QoS labels may further include instruction sets and a fragmentation identifiers used by the egress blade to reassemble the packet fragments. The QoS label, in cooperation with computational and management resources, provide a feedback mechanism to perform real-time bandwidth provisioning within a switch.

Claims

1. A bandwidth provisioning method based on one or more quality of service levels (QoS), defined by one or more policies governing the transmission of protocol data units through a plurality of switching devices comprising the steps of:

(a) appending an inter-switching device label comprising a timestamp to the protocol data unit (PDU) segment at a first switching device, the first switching device comprising a plurality of queues characterized by one or more QoS properties;

(b) buffering the PDU segment in one of the plurality of queues;

(c) conveying the PDU segment to a second switching device;

(d) determining via a fragmentation module to parse the PDU into fragments based on priority queues associated with a different level of priority with a unique QoS, wherein a plurality of QoS policies are applied, the plurality of QoS policies including bandwidth requirements, maximum jitter, queue delay, transit delay, preference and frequency with which a packet is distributed to the switch fabric;

(i) determining, using the timestamp, an observed delay for the PDU segment to propagate between the first switching device and the second switching device; and

(ii) altering at least one of the one or more QoS properties from the second switching device depending on the observed delay.

2. The bandwidth provisioning method of claim 1, wherein the plurality of queues comprise a plurality of ingress queues, the ingress characterized by QoS properties, the QoS properties comprising one or more queuing properties.

3. The bandwidth provisioning method of claim 2, wherein one of the queuing properties is the size of the PDU segment.

4. The bandwidth provisioning method of claim 3, wherein the step of altering one or more queuing properties comprises the step of enabling parsing of at least one PDU into a plurality of PDU fragments.

5. The bandwidth provisioning method of claim 4, wherein the method further comprises the steps of:

(a) removing the QoS label at the second switching device; and

(b) reassembling, at the second switching device, the plurality of PDU fragments into at least one original PDU.

6. The bandwidth provisioning method of claim 4, wherein the step of altering one or more queuing properties comprises the step of defining a maximum fragmentation size into which the at least one PDU is fragmented.

7. The bandwidth provisioning method of claim 6, wherein the step of defining a maximum fragmentation size comprises the step of reducing the maximum fragmentation size associated with one or more ingress queues of the plurality of ingress queues when at least one or more other ingress queues is congested.

8. The bandwidth provisioning method of claim 1, wherein the step of altering one or more QoS properties comprises the step of enabling fragmentation of one or more PDUs at the plurality of queues if the observed delay exceeds a target delay associated with the propagation through the plurality of queues.

9. The bandwidth provisioning method of claim 8, wherein the one or more QoS properties comprise a fragmentation property defining whether to fragment one or more PDUs of one or more traffic flows.

10. The bandwidth provisioning method of claim 8, wherein the one or more QoS properties comprise a fragmentation property defining whether to fragment one or more PDUs of one or more queues.

11. The bandwidth provisioning method of claim 8, wherein the one or more queuing properties comprise a fragmentation property defining whether to fragment a PDU after transmission from the associated queue to a switch fabric has begun but before transmission is completed.

12. The bandwidth provisioning method of claim 1, wherein the PDU segment is a protocol data unit.

13. The bandwidth provisioning method of claim 1, wherein the PDU segment is a PDU fragment.

14. The bandwidth provisioning method of claim 13, wherein the inter-switching device label further comprises a fragment identifier.

15. The bandwidth provisioning method of claim 13, wherein the inter-switching device label further comprises an operation code comprising one or more instructions to the second switching device for processing the PDU fragment.

16. The bandwidth provisioning method of claim 1, wherein the step of altering at least one of the one or more QoS properties comprises altering one or more filtering properties;

and wherein the method further comprises the step of filtering one or more segments of a traffic flow at the first switching device.

17. The bandwidth provisioning method of claim 1, wherein the step of altering at least one of the one or more QoS properties comprises altering one or more shaping properties, and wherein the method further comprises the steps of shaping one or more segments of a traffic flow at the first switching device.

18. A bandwidth provisioning apparatus comprising an ingress queue memory associated with a different level of priority and correlates one or more quality of service levels (QoS) governing the transmission of protocol data units through a plurality of switching devices, the apparatus comprising:

(a) a first switching device, comprising a plurality of queues characterized by one or more QoS properties, for appending an internal label, the internal label comprising a timestamp to one or more PDU segments;

(b) a fragmentation module adapted to parse select ingress PDUs into one or more PDU fragments when one or more queues are adversely impacted due to high bandwidth consumption at one or more other ingress priority queues; and

(c) second switching device, operatively coupled to the first switching device, for;

(i) determining a delay time for the one or more PDU segments to propagate between the first switching device and the second switching device based on the timestamp; and

(ii) altering the one or more QoS properties depending on the time delay.

19. The bandwidth provisioning apparatus of claim 18, wherein the step of altering one or more QoS properties comprises the step of enabling parsing of one or more PDUs into a plurality of PDU fragments.

20. The bandwidth provisioning apparatus of claim 19, wherein the second switching device is adapted for:

(a) removing the internal label from each of the one or more PDU segments; and

(b) reassembling the plurality of PDU fragments into at least one PDU.

21. The bandwidth provisioning apparatus of claim 18, wherein the internal label further comprises a fragment operation code comprising one or more instructions to the second switching device for processing the PDU fragment.

22. The bandwidth provisioning apparatus of claim 18, wherein the first switching device, comprising a plurality of ingress queues, is adapted to generate a maximum fragment size for one or more PDU segments transmitted from at least one of the plurality of ingress queues.

23. The bandwidth provisioning method of claim 18, wherein the first switching device, comprising a plurality of ingress queues, is adapted to fragment one or more PDUs into fragments at the first switching device if the delay time exceeds a target delay.