Methods and apparatus for provisioning connection oriented, quality of service capabilities and services

• US 20050089054A1
• Filed: 08/10/2004
• Published: 04/28/2005
• Est. Priority Date: 08/11/2003
• Status: Abandoned Application

• Current Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Original Assignee: Network Appliance Incorporated (NetApp, Inc.)
• Inventors: Medard, Muriel, Ciancaglini, Gene, Moores, John D., Parquette, Mark R., Proulx, Donald P.
• Application Number:
  US10/915,106
• Publication Number:
  US 20050089054A1
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 49/101 using crossbar or matrix
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/3027 Output queuing
• CPC Class Codes: H04L 49/3045 Virtual queuing

Abstract

The present invention describes a system for providing quality of service (QoS) features in communications switching devices and routers. The QoS provided by this system need not be intrinsic to the communication protocols being transported through the network. Preferred embodiments also generate statistics with the granularity of the QoS. The system can be implemented in a single application-specific integrated circuit (ASIC), in a chassis-based switch or router, or in a more general distributed architecture. The system architecture is a virtual output queued (VOQed) crossbar. The administrator establishes policies for port pairs within the switch, and optionally with finer granularity. Frames are directed to unique VOQs based on both policy and protocol criteria. Policies are implemented by means of a scheduling engine that allocates time slices (minimum units of crossbar access).

Claims

1. A switching device, comprising:

an ingress media access control module to receive incoming frames;

a classification engine to process frame data from the media access control module based upon at least on attribute;

a queue ingress manager to assign data to one of a plurality of queues based upon the processing by the classification engine, and to update registers, tables, and counters describing memory system status;

a plurality of transmit queues to receive data from the queue ingress manager;

a metadata generator coupled to the plurality of queues to encapsulate the data from the transmit queues as the data is transmitted out of the queues;

a switch fabric to receive the encapsulated data;

a queue egress manager coupled to the plurality of transmit queues to manage transmission of frame data from the plurality of transit queues to the switching fabric, and to update registers, tables, and counters describing the memory system status;

a metadata stripper coupled to the switch fabric to strip the encapsulation data;

a receive memory system to store the un-encapsulated data; and

an egress media access control to receive data from the receive memory system.

2. The device according to claim 1, further including a queue flush manager to flush a selected one of the plurality of transmit queues, and to update registers, tables, and counters describing the memory system status.

3. The device according to claim 1, wherein the plurality of transmit queues differentiate data flows through the device.

4. The device according to claim 1, where an administrative user interface enables an administrator to establish policy groups of switch ports, and to establish QoS policies between pairs of policy groups.

5. The device according to claim 4, wherein the QoS policies includes at least one of minimum bandwidth guarantee through the device, a maximum bandwidth, distributing excess bandwidth according to need, distributed excess bandwidth fairly when egress is congested, bounded jitter, and release of unused minimum bandwidth.

6. The device according to claim 1, wherein a centralized scheduling/arbitration engine upholds policies established through the administrative user interface.

7. The device according to claim 1, wherein a centralized scheduling/arbitration engine upholds minimum bandwidth policies, by reserving sufficient time slices per epoch for the ports in the associated policy groups.

8. The device according to claim 1, wherein the device provides QoS through the device for data in a connectionless format.

9. The device according to claim 8, wherein the connectionless format is selected from one or more of Ethernet, Fibre Channel class 2 and Fibre Channel class 3.

10. The device according to claim 1, wherein the encapsulated data includes metadata for at least one of global source address, local source port ID, source queue ID, global destination address, local destination port ID, destination queue ID, underlying protocol ID, application ID, flow ID, frame drop classification, and priority.

11. The device according to claim 1, wherein the plurality of transmit queues include virtual output queues.

12. The device according to claim 1, wherein the device includes a virtual output queued scheduled crossbar switched architecture using slotted time division multiplexing.

13. The device according to claim 1, further including parameter and/or statistic feedback for use by the queue ingress manager.

14. The device according to claim 13, further including ingress and egress feedback for processing by a scheduling/arbitration engine to optimize bandwidth allocation based upon usage and congestion.

15. The device according to claim 14, further including a mechanism to send scheduler allocation messages to ports to inform the ports as to which of the plurality of queues should transmit during a given time slice.

16. The device according to claim 1, further including a plurality of ports each of which is assigned to one of a plurality of policy groups.

17. The device according to claim 1, wherein a connection is assigned a minimum bandwidth and a maximum bandwidth.

18. The device according to claim 1, further including scheduling bandwidth on an epoch basis.

19. The device according to claim 1, further including a connection control engine to emulate at least one feature of a Fibre Channel Class 4 device.

20. The device according to claim 1, further including a further switching device supporting QoS policies for connectionless data flows coupled to the switching device to provide end-to-end QoS guarantees from the switching device to the further switching device.

21. A switching device, comprising:

a switching fabric; and

a processing means coupled to the switching fabric, the processing means to enable meeting QoS requirements for data in a connectionless format.

22. The device according to claim 21, wherein the connectionless format includes one or more of Ethernet, Fibre Channel Class 2 and Fibre Channel class 3.

23. The device according to claim 21, wherein the QoS requirements includes at least one of minimum bandwidth guarantee through the device, a maximum bandwidth, distributing excess bandwidth according to need, distributed excess bandwidth fairly when egress is congested, bounded jitter, and release of unused minimum bandwidth.

24. The device according to claim 21, wherein the processing means includes a metadata generator means to encapsulate the data prior to transmission to the switching fabric.

25. The device according to claim 24, wherein the processing means includes a plurality of transmit queues.

26. The device according to claim 25, wherein the processing means includes a transmit queue ingress manager coupled to the plurality of transmit queues.

27. The device according to claim 26, wherein the processing means includes a transmit queue egress manager coupled to the transmit queues.

28. The device according to claim 27, wherein the processing means further includes a metadata stripper.

29. The device according to claim 28, wherein the processing means further includes a queue flush manager to flush a selected one of the plurality of queues.

30. The device according to claim 21, wherein the processing means is provided on a line card.

31. The device according to claim 25, a control means to enable a centralized scheduler/arbitration engine to communicate to ports which of the plurality of queues is permitted to transmit into the switching fabric.

32-44. -44. (canceled)

45. A method comprising:

receiving data at a first port within a network switching device;

queuing the received data into a plurality of queues;

causing data to be output from specific ones of the queues, based on a set of QoS criteria and time dependent attributes of the plurality of queues;

associating the data output from the queues with QoS related metadata; and

transmitting the data output from the queues and the associated metadata into a switching fabric within the network switching device, for transmission to a second port within the network switching device.

46. A method as recited in claim 45, further comprising:

transmitting the data from the second port to a device which is external to the network switching device.

47. A method as recited in claim 46, further comprising, in the second port, prior to transmitting the data from the second port to the device which is external to the network switching device:

removing the metadata from the data transmitted through the switching fabric to the second port.

48. A method as recited in claim 45, wherein associating data output from the queues with metadata comprises encapsulating data output from the queues with metadata.

49. A method as recited in claim 45, further comprising:

providing feedback to the scheduling/arbitration engine regarding time-dependent attributes of the plurality of queues, wherein said operating the flow control mechanism is based on the feedback.

50. A method as recited in claim 45, wherein the method is performed within a storage server.

51. A method as recited in claim 45, wherein the data received at the first port is in a connectionless format.

52. A method as recited in claim 45, further comprising:

dynamically allocating memory to the queues on an as-needed basis.