Multi-stage packet switching system with alternate traffic routing

• US 20060165112A1
• 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 7,489,625 B2
• Time in Patent Office: Days
• US Class Current: 370/428
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/62 Wavelength based optical switching H04Q11/0062
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/357 Fibre channel switches
• CPC Class Codes: H04L 49/557 Error correction, e.g. fault recovery or fault tolerance
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0039 Electrical control
• CPC Class Codes: H04Q 2011/0045 Synchronisation
• CPC Class Codes: H04Q 2011/005 Arbitration and scheduling
• CPC Class Codes: H04Q 2011/0058 Crossbar; Matrix
• CPC Class Codes: H04Q 3/68 Grouping or interlacing selector groups or stages

Abstract

In general, in one aspect, the disclosure describes a multi-stage switch having a plurality of ingress switching modules to receive data and to generate frames that are transmitted as a wavelength division multiplexed signal. The multi-stage switch further includes a core switching 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 a plurality of egress switching modules to receive the wavelength division multiplexed signal from the core switch module and to transmit data. The multi-stage switch is capable of detecting faulty paths and transmitting data through fault-free paths.

Claims

1. A multi-stage switch comprising:

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

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

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

wherein the switch is capable of detecting faulty paths and transmitting data through fault-free paths.

2. The switch of claim 1, wherein said plurality of ingress switching modules detect the faulty paths and transmit the data to selected ones of said plurality of egress switching modules via the fault-free paths.

3. The switch of claim 2, wherein at least one of said plurality of ingress switching modules include a scheduler that inactivates the faulty paths when generating a schedule.

4. The switch of claim 3, wherein said at least one of said plurality of ingress switching modules further include a plurality of egress modules and wherein the scheduler includes a data array that indicates which egress modules are faulty and the data paths associated with the faulty egress modules are deactivated.

5. The switch of claim 3, wherein at least one of said plurality of egress switching modules include a plurality of ingress modules and wherein the scheduler includes a data array that indicates which ingress modules associated with the at least one of said plurality of egress switching modules are faulty and the data paths associated with the faulty ingress modules are deactivated.

6. The switch of claim 1, wherein

at least one of said plurality of ingress switching modules includes a plurality of egress modules and a scheduler;

at least one of said plurality of egress switching modules includes a plurality of ingress modules; and

the scheduler includes a first data array that indicates a fault status for the egress modules within the at least one of said plurality of ingress switching modules and a second data array that indicates a fault status for the ingress modules within the at least one of said plurality of egress switch modules, wherein the scheduler can deactivate faulty paths based on the first data array or the second data array.

7. The switch of claim 6, wherein the first array indicates a fault status for the egress modules of fault-free or faulty.

8. The switch of claim 6, wherein the second array is a two dimensional array indexed by egress switching module and the ingress module within the egress switching module.

9. The switch of claim 6, wherein the scheduler determines the faulty paths by bit wise ANDing the first data array and a portion of the second data array that is associated with the egress switching module for which the ingress switching module is requesting to transmit data to.

10. The switch of claim 9, wherein the scheduler disables the egress modules associated with faulty paths.

11. The switch of claim 10, wherein the scheduler generates a schedule for switching data across the ingress switch module after the egress modules associated with faulty paths are disabled.

12. The switch of claim 6, wherein the scheduler includes a third data array that tracks data stored in the egress modules and the scheduler issues grants at least in part based on the third data array.

13. The switch of claim 1, wherein said plurality of ingress switching modules include a set of internal sub-modules, and wherein a particular ingress switching module distributes data packets destined for a particular egress switching module across the set of internal sub-modules such that the data packets destined to the particular egress switching module are distributed as evenly as possible across the set of internal sub-modules.

14. The switch of claim 13, wherein data packets queued in different sub-modules associated with the particular ingress switching module and destined to the particular egress switching module are switched in parallel across the core switching module to the particular destination egress switching module.

15. The switch of claim 1, wherein said 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.

16. The switch of claim 1, wherein said plurality of ingress switching modules comprise 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.

17. The switch of claim 16, wherein said plurality of ingress switching modules further include a framer and wavelength division multiplexer transmitter to form frames from stored segments and create a wavelength division multiplexed optical signal of the frames.

18. The switch of claim 1, wherein said plurality of egress switching modules comprise 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 an egress scheduler to control data transfer there through.

19. The switch of claim 18, wherein said plurality of egress switching modules further include a wave division receiver and deframer to receive wavelength division multiplexed signals from said core switching module and extract frames there from.

20. 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 switching module;

within the ingress switching modules, switching the data, aggregating the data destined for different egress switching module into frames, generating wavelength-division multiplexed (WDM) optical signals from the frames, and transmitting the WDM optical signals to the core switching module;

switching the WDM optical signals through the core switch module via multiple channels;

within the egress switching modules, receiving the WDM optical signals, extracting frames from the WDM optical signals, switching the data, and transmitting the data to destinations;

detecting faulty paths; and

switching data through fault-free paths.

21. The method of claim 20, further comprising disabling the faulty paths.

22. The method of claim 20, wherein said detecting includes detecting faulty paths between an ingress switching module ready to transmit data and an associated egress switching module.

23. The method of claim 20, wherein said detecting includes checking data array for fault status of egress modules within the ingress switching module.

24. The method of claim 20, wherein said detecting includes checking data array for fault status of ingress modules within the associated egress switching module.

25. The method of claim 20, wherein said detecting includes

checking a first data array for fault status of egress modules within the ingress switching module;

checking a second data array for fault status of ingress modules within the associated egress switching module; and

bit wise ANDing the first data array and the second data array.

26. 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, segment them, aggregate them into frames, and transmit the frames over optical wavelength division multiplexed channels;

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

at least one egress switch module to receive the wavelength division multiplexed signals from the core switch module, extract segments from them, switch the segments to the destination ports, reassemble the segments arriving at the destination ports into packets, and to transmit the packets to the Ethernet cards,

wherein the multistage switch is capable of detecting faulty paths and transmitting data through fault-free paths.

27. The device of claim 26, wherein said at least one ingress switch module includes a scheduler that inactivates the faulty paths when generating a schedule.

28. The device of claim 27, wherein said at least one ingress switch module further includes a plurality of egress modules and wherein the scheduler includes a data array that indicates which egress modules are faulty and the data paths associated with the faulty egress modules are deactivated.

29. The device of claim 27, wherein said at least one egress switch module includes a plurality of ingress modules and wherein the scheduler includes a data array that indicates which ingress modules associated with said at least one egress switch module is faulty and the data paths associated with the faulty ingress modules are deactivated.

30. The device of claim 26, wherein

said at least one ingress switch module includes a plurality of egress modules and a scheduler;

said at least one egress switch module includes a plurality of ingress modules; and

the scheduler includes a first data array that indicates which egress modules within said at least one ingress switch module are faulty and a second data array that indicates which ingress modules within said at least one egress switch modules are faulty, wherein the scheduler deactivates faulty paths based on the first data array and the second data array.

31. The device of claim 30, wherein the scheduler determines the faulty paths by bit wise ANDing the first data array and a portion of the second data array that is associated with the egress switch module for which the ingress switching module is requesting to transmit data to.

32. The device of claim 31, wherein the scheduler disables the egress modules associated with faulty paths.