FLOW-CONTROL IN A SWITCH FABRIC

• US 20100165843A1
• Filed: 12/29/2008
• Published: 07/01/2010
• Est. Priority Date: 12/29/2008
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Thomas, Philip A.
• Granted Patent: US 8,254,255 B2
• Time in Patent Office: Days
• US Class Current: 370/235
• CPC Class Codes: H04L 12/50 Circuit switching systems, i.e. systems in which the path is physically permanent during the communication
• CPC Class Codes: H04L 49/1515 Non-blocking multistage, e.g. Clos
• CPC Class Codes: H04Q 3/68 Grouping or interlacing selector groups or stages

Abstract

In some embodiments, an apparatus includes a module within a first stage of a switch fabric, a module within a second stage of the switch fabric, and a module within a third stage of the switch fabric. The module within the first stage is configured to send data to the module within the second stage. The module within the second stage is configured to send data to the module within the third stage. The module within the second stage is configured to send a first suspension indicator to the module within the third stage. The module within the third stage is configured to send a second suspension indicator to the module within the first stage in response to the first suspension indicator. The module within the first stage is configured to stop sending data to the module within the second stage in response to the second suspension indicator.

Claims

1. An apparatus, comprising:

a module within a first stage of a switch fabric;

a module within a second stage of the switch fabric, the module within the first stage configured to send data to the module within the second stage; and

a module within a third stage of the switch fabric, the module within the second stage configured to send data to the module within the third stage,

the module within the second stage configured to send a first suspension indicator to the module within the third stage, the module within the third stage configured to send a second suspension indicator to the module within the first stage in response to the first suspension indicator, the module within the first stage configured to stop sending data to the module within the second stage in response to the second suspension indicator.

2. The apparatus of claim 1, wherein the module within the third stage is configured to send a third suspension indicator to the module within the first stage, the module within the first stage configured to send a fourth suspension indicator to the module within the second stage in response to the third suspension indicator, the module within the second stage configured to stop sending data to the module within the third stage in response to the fourth suspension indicator.

3. The apparatus of claim 1, wherein the module within the first stage and the module within the third stage are within a same chip package.

4. The apparatus of claim 1, wherein the module within the second stage is within a first chip package, the module within the first stage and the module within the third stage is within a second chip package different from the first chip package.

5. The apparatus of claim 1, further comprising:

a module within a fourth stage of the network fabric configured to send data to the first module; and

a module within a fifth stage of the network fabric configured to receive data from the third module,

the module within the first stage configured to send a third suspension indicator to the module within the third stage, the module within the third stage configured to send a fourth suspension indicator to the module within the fifth stage in response to the third suspension indicator, the module within the fifth stage configured to send a fifth suspension indicator to the module within the fourth stage, the module within the fourth stage configured to stop sending data to the module within the first stage in response to the fifth suspension indicator.

6. The apparatus of claim 1, wherein the module within the fourth stage and the module within the fifth stage are within a same chip package.

7. The apparatus of claim 1, wherein the module within the second stage is configured to send the first suspension indicator to the module within the third stage when the module within the second stage is unable to receive additional data from the module within the first stage.

8. The apparatus of claim 1, wherein the module within the second stage includes a queue within a memory configured to buffer data, the module within the second stage is configured to send the second suspension indicator to the module within the third stage when an amount of data within the queue exceeds a threshold.

9. The apparatus of claim 1, wherein the module within the second stage is configured to send data to the module within the third stage via a data connection, the module within the second stage is configured to send the second suspension indicator to the module within the third stage via the data connection.

10. The apparatus of claim 1, wherein the module within the second stage is configured to send a first actuation indicator to the module within the third stage, the module within the third stage is configured to send a second actuation indicator to the module within the first stage in response to the first actuation indicator, the module within the first stage is configured to send data from the module within the first stage to the module within the second stage in response to the second actuation indicator.

11. A method, comprising:

sending data from a module within a first stage of a switch fabric to a module within a second stage of the switch fabric;

sending a first suspension indicator from the module within the second stage to a module within a third stage of the switch fabric; and

sending a second suspension indicator from the module within the third stage to the module within the first stage in response to the first suspension indicator, the module within the first stage configured to stop sending data to the module within the second stage in response to the second suspension indicator.

12. The method of claim 11, further comprising:

sending a first actuation indicator from the module within the second stage to the module within the third stage;

sending a second actuation indicator from the module within the third stage to the module within the first stage in response to the first actuation indicator, the module within the first stage configured to resume sending data to the module within the second stage in response to the second actuation indicator.

13. The method of claim 11, wherein the first suspension indicator is sent from the module within the second stage to the module within the third stage when an amount of data in a buffer of the module within the second stage exceeds a threshold.

14. A processor-readable medium storing code representing instructions to cause a processor to perform a process, the code comprising code to:

receive data from a module within a first stage of a switch fabric;

buffer the data in a queue within a memory;

forward the buffered data to a module within a second stage of the switch fabric; and

send a suspension indicator to the module within the second stage when an amount of data within the queue exceeds a threshold, the suspension indicator configured to stop the module within the first stage from sending data.

15. The processor-readable medium of claim 14, the code further comprising code to:

send an actuation indicator to the module within the second stage, the actuation indicator configured to request data from the module within the first stage.

16. An apparatus, comprising:

a module within a first stage of a switch fabric;

a module within a second stage of the switch fabric;

a module within a third stage of the switch fabric;

a first unidirectional data path, the first unidirectional data path configured to facilitate data transfer from the module within the first stage to the module within the second stage;

a second unidirectional data path, the second unidirectional data path configured to facilitate data transfer from the module within the second stage to the module within the third stage; and

a bidirectional data path configured to facilitate transfer of a flow-control indicator from the module within the third stage to the module within the first stage.

17. The apparatus of claim 16, wherein the flow-control indicator is configured to cause the module within the first stage to stop sending data to the module within the second stage.

18. The apparatus of claim 16, wherein the flow-control indicator is configured to cause the module within the first stage to send data to the module within the second stage.

19. The apparatus of claim 16, wherein the module within the second stage includes a buffer, the module within the second stage configured to send a flow-control indicator to the module within the third stage in response to an amount of data in the buffer exceeding a threshold, the flow-control indicator is configured to cause the module within the third stage to send the flow-control indicator from the module within the third stage to the module within the first stage.

20. The apparatus of claim 16, wherein the module within the first stage and the module within the third stage are within a same chip package.

21. The apparatus of claim 16, wherein the module within the second stage is within a first chip package, the first module and the third module are within a second chip package different from the first chip package.

22. The apparatus of claim 16, wherein the module within the third stage is configured to send the flow-control indicator to the module within the first stage when the module within the second stage is unable to receive additional data from the module within the first stage.

23. The apparatus of claim 16, wherein the module within the second stage is configured to send a flow-control indicator to the module within the third stage via the second unidirectional data path.