Multi-stage packet switching system

• US 20060165098A1
• Filed: 01/27/2005
• Published: 07/27/2006
• Est. Priority Date: 01/27/2005
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Varma, Anujan
• Granted Patent: US 7,590,102 B2
• Time in Patent Office: Days
• US Class Current: 370/397
• CPC Class Codes: H04L 49/101 using crossbar or matrix
• CPC Class Codes: H04L 49/1523 Parallel switch fabric planes

Abstract

In general, in one aspect, the disclosure describes a multi-stage switch having at least one ingress switch module to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal. The multi-stage switch further includes a core switch module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the frames. The multi-stage switch additionally includes at least one egress switch module to receive the wavelength division multiplexed signal from the core switch module and to transmit data.

Claims

1. A multi-stage switch comprising:

at least one ingress switch module to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal;

a core switch module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the frames; and

at least one egress switch module to receive the wavelength division multiplexed signal from the core switch module and to transmit data.

2. The switch of claim 1, wherein the at least one ingress switch module includes a set of internal sub-modules and a particular ingress switch module distributes data destined for a particular egress switch module across the set of internal sub-modules such that the data destined to the particular egress switch module is distributed as evenly as possible across the set of internal sub-modules.

3. The switch of claim 2, wherein the data is queued in the set of internal sub-modules.

4. The switch of claim 3, wherein the data is queued by at least some subset of egress switch module and priority.

5. The switch of claim 3, wherein the data queued in different sub-modules associated with a particular ingress switch module and destined to a particular egress switch module are switched in parallel across the core switch module to the particular destination egress switch module.

6. The switch of claim 5, wherein the data is switched utilizing multiple channels in the core switch module.

7. The switch of claim 6, wherein wave division multiplexing is used to form the multiple channels.

8. The switch of claim 5, wherein the at least one egress switch module includes a set of internal sub-modules and the particular egress switch module uses the set of internal sub-modules to receive the data arriving from the core switch module.

9. The switch of claim 8, wherein the set of sub-modules receives the data from the channels of the core switch module and directs them to an appropriate output port of the egress switch module.

10. The switch of claim 1, wherein the at least one ingress switch module, the core switch module, and the at least one egress switch module are controlled by separate schedulers.

11. The switch of claim 10, wherein at least some subset of the schedulers operate on a pipeline schedule.

12. The switch of claim 1, wherein said at least one ingress switch module comprises at least one ingress queuing engine operatively connected to transmit data to at least one crossbar switch plane, which is operatively connected to transmit data to at least one ingress crossbar data element and wherein data transfer is controlled by an ingress scheduler.

13. The switch of claim 12, wherein said ingress scheduler includes an ingress crossbar data element array that tracks data stored in the at least one ingress crossbar data element.

14. The switch of claim 12, wherein said at least one ingress switch module further includes a framer and wavelength division multiplexer transmitter to form frames from stored segments and create a wavelength division multiplexed-signal of the frames from the at least one ingress crossbar data elements.

15. The switch of claim 14, wherein the frames within the wavelength division multiplexed signal from one of the at least one ingress switch modules are associated with one of the at least one egress switch modules.

16. The switch of claim 1, wherein said core switch module comprises an optical crossbar switch plane.

17. The switch of claim 1, wherein said at least one egress switch module comprises at least one egress crossbar data element operatively connected to transmit data to at least one crossbar switch plane, which is operatively connected to transmit data to at least one egress queuing engine and wherein data transfer is controlled by an egress scheduler.

18. The switch of claim 17, wherein said at least one egress switch module further includes a wave division receiver and deframer to receive a wavelength division multiplexed-signal of frames from the at least one ingress crossbar data elements and extract segments from the frames.

19. A method comprising:

receiving data at a multistage switch, wherein the multistage switch includes a plurality of ingress switching modules, a core switching module operationally connected to the plurality of ingress switching modules, and a plurality of egress switching modules operationally connected to the core switch module;

switching the data through the plurality of ingress switching modules;

forming frames from the data for transmission across multiple channels as a wavelength division multiplexed signal;

switching the frames transmitted as the wavelength division multiplexed signal through the core switch module;

extracting the data from the wavelength division multiplexed signal;

switching the data through the plurality of egress switching modules; and

transmitting the data to destinations.

20. The method of claim 19, wherein said switching the data through a plurality of ingress switching modules includes

storing the data in a plurality of queues as segments;

forming frames for queues selected to switch data; and

switching the frames from an ingress module to an egress module.

21. The method of claim 20, wherein said switching the data through a plurality of ingress switching modules further includes

sending requests to a scheduler, wherein the requests are for permission to switch data from a queue to an egress module;

generating a schedule based on the requests; and

transmitting grants to selected queues.

22. The method of claim 19, wherein said forming is done by the ingress switching module.

23. The method of claim 19, wherein said extracting is done by the egress switching modules.

24. The method of claim 19, wherein said switching the data through a plurality of egress switching modules includes

storing the data in a plurality of queues as segments;

forming frames for queues selected to switch data; and

switching the frames from an ingress module to an egress module.

25. The method of claim 24, wherein said switching the data through a plurality of ingress switching modules further includes

sending requests to a scheduler, wherein the requests are for permission to switch data from a queue to an egress module;

generating a schedule based on the requests; and

transmitting grants to selected queues.

26. A multi-stage switch comprising,

a plurality of ingress switch modules to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal;

a core switch module operatively connected to receive the wavelength division multiplexed signal from the plurality of ingress switch modules and to switch the frames; and

a plurality of egress switch modules to receive the wavelength division multiplexed signal from the core switch module and to transmit the data, wherein

the plurality of ingress switch modules include a set internal sub-modules to distribute the data such that data destined to a particular egress switch module is distributed as evenly as possible across the sub-modules;

the data queued in different sub-modules associated with a particular ingress switch module and destined to a particular egress switch module are switched in parallel across the core switch module to the particular destination egress switch module utilizing multiple channels in the core switch module; and

the plurality of egress switch modules include a set of internal sub-modules to receive the data arriving from the core switch module and direct the data to the appropriate output port of the egress switch module.

27. The switch of claim 26, wherein the plurality of ingress switch modules, the core switch module, and the plurality of egress switch modules are controlled by separate schedulers.

28. The switch of claim 27, wherein at least some subset of the schedulers operate on a pipeline schedule.

29. The switch of claim 26, wherein said plurality of ingress switch modules include

a plurality of ingress interface modules to receive the data, store the data as segments in associated queues, form ISM frames for selected queues, and transmit the ISM frames, wherein the queues are associated with at least some subset of destination and priority;

a scheduler to receive requests from at least some subset of the plurality of ingress interface modules and to generate a schedule;

a plurality of egress interface modules to receive the ISM frames, extract the segments from the ISM frames, and store the segments in associated queues, wherein the queues are associated with at least some subset of destination and priority;

a crossbar switch, responsive to the scheduler, to selectively connect the plurality of ingress interface modules and the plurality of egress interface modules; and

a framer to receive the segments from at least some subset of the plurality of egress interface modules, form CSM frames, create the wavelength division multiplexed signal from the CSM frames, and transmit the wavelength division multiplexed signal.

30. The switch of claim 26, wherein said core switch module includes a scheduler and at least one optical switch.

31. The switch of claim 26, wherein said plurality of egress switch modules include

a deframer to receive the WDM signal, extract the CSM frames therefrom, and extract segments from the CSM frames;

a plurality of ingress interface modules to receive the segments, store the segments in associated queues, form ESM frames for selected queues, and transmit the ESM frames, wherein the queues are associated with at least some subset of destination and priority;

a scheduler to receive requests from the plurality of ingress interface modules and to generate a schedule;

an egress interface module to receive the ESM frames, extract segments from the ESM frames, store the segments in associated queues, and transmit data to destinations; and

a crossbar switch, responsive to the scheduler, to selectively connect the plurality of ingress interface modules and the plurality of egress interface modules.

32. A store and forward device comprising

a plurality of Ethernet cards to receive data from and transmit data to external sources;

and

a multistage switch to switch data between Ethernet cards, the multistage switch including

at least one ingress switch module to receive data from the Ethernet cards and to generate frames that are transmitted as a wavelength division multiplexed signal;

a core switch module operatively connected to receive the wavelength division multiplexed signal from the at least one ingress switch module and to switch the constituent frames; and

at least one egress switch module to receive the wavelength division multiplexed signal from the core switch module and to transmit data to the Ethernet cards.

33. The device of claim 32, wherein the at least one ingress switch module includes

at least one ingress queuing engine to receive data from the plurality of Ethernet cards, store the data as segments in associated queues, and form ISM frames for selected queues;

at least one crossbar switch plane operatively connected to receive the ISM frames from the at least one ingress queuing engine;

at least one ingress crossbar data element operatively connected to receive the ISM frames from the at least one crossbar switching plane, extract the segments from the ISM frames, and store the segments;

an ingress scheduler operationally connected to receive requests from the at least one ingress queuing engine and to configure the at least one crossbar switch plane based on a schedule arbitrated based on received requests; and

a framer operationally connected to receive the segments from the at least one ingress crossbar data element, form CSM frames from the segments, create the wavelength division multiplexed signal from the CSM frames, and transmit the wavelength division multiplexed signal.

34. The device of claim 32, wherein said core switch module comprises an optical crossbar switch plane to switch the WDM signals.

35. The device of claim 32, wherein the at least one egress switch module includes

a deframer to receive the WDM signal, extract the CSM frames therefrom, and extract segments from the CSM frames;

at least one egress crossbar data element operatively connected to receive the segments from the deframer, store the segments in associated queues, and form ESM frames for selected queues;

at least one crossbar switch plane operatively connected to receive the ESM frames from the at least one egress crossbar data element;

at least one egress queuing engine to receive the ESM frames from the at least one crossbar switch plane; and

an egress scheduler operationally connected to receive requests from the at least one egress crossbar data element and to configure the at least one crossbar switch plane based on a schedule arbitrated based on received requests.