Multi-stage packet switching system

• US 7,590,102 B2
• Filed: 01/27/2005
• Issued: 09/15/2009
• Est. Priority Date: 01/27/2005
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Varma, Anujan
• Primary Examiner(s): Sheikh; Ayaz R
• Assistant Examiner(s): Wong; Blanche
• Application Number:
  US11/044,242
• Publication Number:
  US 20060165098A1
• Time in Patent Office: 1,692 Days
• Field of Search: 370/351, 370/388, 370/391, 379/271, 379/272, 379/219, 379/220
• US Class Current: 370/351
• 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 method comprising:

receiving data packets 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 packets through the plurality of ingress switching modules, wherein said switching the data packets through a plurality of ingress switching modules includes

storing the data packets in a plurality of queues;

forming frames from the data packets in queues selected for switching; and

switching the frames from ingress queuing engines to ingress crossbar data elements;

forming, in the plurality of ingress switching modules, core frames from the data packets switched through the plurality of ingress switching modules;

combining, in the plurality of ingress switching modules, a plurality of the core frames into a wavelength division multiplexed signal;

switching the wavelength division multiplexed signal through the core switch module;

separating, in the plurality of egress switching modules, the plurality of the core frames from the wavelength division multiplexed signal;

extracting, in the plurality of egress switching modules, the data packets from the plurality of the core frames;

switching the data packets extracted from the plurality of the core frames through the plurality of egress switching modules; and

transmitting the switched data packets from the plurality of egress switching modules.

2. The method of claim 1, wherein said switching the data packets through a plurality of ingress switching modules further includes

sending requests to an ingress scheduler, wherein the requests are for permission to switch the data packets from the ingress queuing engines to the ingress crossbar data elements;

generating a schedule based on the requests; and

transmitting grants to the ingress queuing engines based on the schedule.

3. A method comprising:

receiving data packets 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 packets through the plurality of ingress switching modules;

forming, in the plurality of ingress switching modules, core frames from the data packets switched through the plurality of ingress switching modules;

combining, in the plurality of ingress switching modules, a plurality of the core frames into a wavelength division multiplexed signal;

switching the wavelength division multiplexed signal through the core switch module;

separating, in the plurality of egress switching modules, the plurality of the core frames from the wavelength division multiplexed signal;

extracting, in the plurality of egress switching modules, the data packets from the plurality of the core frames;

switching the data packets extracted from the plurality of the core frames through the plurality of egress switching modules, wherein said switching the data packets through a plurality of egress switching modules includes

storing the data packets in a plurality of queues;

forming frames from the data packets in queues selected for switching; and

switching the frames from egress crossbar data elements to egress queuing engines; and

transmitting the switched data packets from the plurality of egress switching modules.

4. The method of claim 3, wherein said switching the data packets through a plurality of egress switching modules further includes

sending requests to an egress scheduler, wherein the requests are for permission to switch the data packets from the egress crossbar data elements to the egress queuing engines;

generating a schedule based on the requests; and

transmitting grants to the egress crossbar data elements based on the schedule.

5. A store and forward device comprising:

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

a multistage switch to switch the data packets between the plurality of Ethernet cards, the multistage switch including

a plurality of ingress switch modules, wherein each ingress switch module includes a plurality of ingress queuing engines to receive the data packets from the plurality of Ethernet cards and to form frames from the data packets, at least one ingress crossbar switch plane to switch the data packets within the frames through the ingress switch module, a plurality of ingress crossbar data elements to extract the switched data packets from the switched frames, and a framer to create core frames from the switched data packets, and to combine a plurality of the core frames into a wavelength division multiplexed signal;

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

a plurality of egress switch modules, wherein each egress switch module is to receive the wavelength division multiplexed signals from the core switch module, to separate the core frames from the wavelength division multiplexed signals, to extract the data packets from the core frames, to form frames from the data packets, to switch the data packets within the frames therethrough, to extract the switched data packets from the switched frames, and to transmit the data packets to the plurality of Ethernet cards.

6. The device of claim 5, wherein each ingress switch module further includes

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.

7. The device of claim 5, wherein said core switch module comprises an optical crossbar switch plane to switch the WDM signals.

8. The device of claim 5, wherein the 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;

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.

9. A multi-stage switch fabric comprising:

a plurality of ingress switch modules, wherein each ingress switch module is to receive data packets via a plurality of ingress ports, to form frames from the data packets, to switch the data packets within the frames therethrough, to extract the switched data packets from the switched frames, to create core frames from the switched data packets, and to combine a plurality of the core frames into a wavelength division multiplexed signal;

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

a plurality of egress switch modules, wherein each egress switch module includes a deframer to receive the wavelength division multiplexed signals from the core switch module and to separate the core frames from the wavelength division multiplexed signals, a plurality of egress crossbar data elements to extract the data packets from the core frames and to form frames from the data packets, at least one egress crossbar switch plane to switch the data packets within the frames through the egress switch module, and a plurality of egress queuing engines to extract the switched data packets from the switched frames and to transmit the data packets via a plurality of egress ports.

10. The switch of claim 9, wherein the plurality of ingress switch modules include a plurality of ingress queuing engines, a plurality of ingress crossbar data elements, at least one ingress crossbar switch plane to selectively connect the plurality of plurality of ingress queuing engines and the plurality of ingress crossbar data elements, and an ingress scheduler to control the at least one ingress crossbar switch plane.

11. The switch of claim 10, wherein the plurality of ingress switch modules further include a framer and wavelength division multiplexer transmitter.

12. The switch of claim 10, wherein the ingress scheduler includes an ingress crossbar data element array that tracks data stored in the plurality of ingress crossbar data elements.

13. The switch of claim 12, wherein the ingress scheduler configures the at least one ingress crossbar switch plane so that data packets destined for one of the plurality of egress switch modules are transmitted from the plurality of ingress queuing engines as evenly as possible to the plurality of ingress crossbar data elements.

14. The switch of claim 10, wherein the plurality of ingress queuing engines store the received data packets as segments and form ingress frames from the segments and transmit the ingress frames over the at least one ingress crossbar switch plane.

15. The switch of claim 13, wherein the segments are stored in a plurality of queues, wherein the queues are based on at least egress switch module the data packets are destined for.

16. The switch of claim 10, wherein the plurality of ingress crossbar data elements divide the received ingress frames into the segments and store the segments in queues based on at least egress switch module the data packets are destined for.

17. The switch of claim 16, wherein the ingress crossbar data elements form the core frames from the segments associated with one of the plurality of egress switch modules and combine the core frames associated with the one of the plurality of egress switch modules into the wavelength division multiplexed signal.

18. The switch of claim 9, wherein the wavelength division multiplexed signals are switched utilizing multiple channels in the core switch module.

19. The switch of claim 18, wherein wave division multiplexing is used to form the multiple channels.

20. The switch of claim 9, wherein said core switch module comprises an optical crossbar switch plane.

21. The switch of claim 9, wherein the plurality of egress switch modules further include an egress scheduler to control the at least one egress crossbar switch plane.

22. The switch of claim 21, wherein the plurality of egress crossbar data elements store the extracted data packets as segments and form egress frames from the segments and transmit the egress frames over the at least one egress crossbar switch plane.

23. The switch of claim 9, 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.

24. The switch of claim 23, wherein at least some subset of the schedulers operate on a pipeline schedule.

25. The switch of claim 9, wherein the plurality of ingress switch modules include

a plurality of ingress interface modules to receive the data packets, store the data packets 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 of the data packets;

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;

an ingress 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 from the segments, create the wavelength division multiplexed signal from the CSM frames, and transmit the wavelength division multiplexed signal.

26. The switch of claim 9, wherein said plurality of egress switch modules further include

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

and wherein the

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