Methods and apparatus for transmission of groups of cells via a switch fabric

• US 8,325,749 B2
• Filed: 12/24/2008
• Issued: 12/04/2012
• Est. Priority Date: 12/24/2008
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Thomas, Sarin, Vegesna, Srihari, Sindhu, Pradeep, Chen, Chi-Chung Kenny, Frailong, Jean-Marc, Ofelt, David J., Thomas, Philip A., Wu, Chang-Hong
• Primary Examiner(s): Phillips, Hassan
• Assistant Examiner(s): EBRAHIM, ANEZ C
• Application Number:
  US12/343,728
• Publication Number:
  US 20100158031A1
• Time in Patent Office: 1,441 Days
• Field of Search: 370/235, 370/254, 370/363, 370/389, 370/390, 370/392, 370/393, 370/401, 370/442, 370/495, 386/95, 386/125
• US Class Current: 370/412
• CPC Class Codes: H04J 3/00 Time-division multiplex systems H04J14/00 takes precedence; relay systems H04B7/14; selecting techniques H04Q
• CPC Class Codes: H04L 49/251 Cut-through or wormhole routing
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling

Abstract

In one embodiment, a method can include receiving at an egress schedule module a request to schedule transmission of a group of cells from an ingress queue through a switch fabric of a multi-stage switch. The ingress queue can be associated with an ingress stage of the multi-stage switch. The egress schedule module can be associated with an egress stage of the multi-stage switch. The method can also include determining, in response to the request, that an egress port at the egress stage of the multi-stage switch is available to transmit the group of cells from the multi-stage switch.

Claims

1. A method, comprising:

receiving, from an ingress schedule module and at an egress schedule module, a request to schedule transmission of a group of cells from an ingress queue through a multi-stage switch fabric of a multi-stage switch, the request including a sequence value representing an order within the group of cells within the ingress queue, the ingress queue being associated with an ingress stage of the multi-stage switch fabric, the ingress schedule module being associated with the ingress stage of the multi-stage switch fabric, the egress schedule module being associated with an egress stage of the multi-stage switch fabric;

defining, in response to the request, a response including the sequence value associated with the group of cells when an egress port associated with the egress stage of the multi- stage switch fabric is available to transmit the group of cells from the multi-stage switch; and

sending the response from the egress schedule module to the ingress schedule module.

2. The method of claim 1, wherein the multi-stage switch fabric has a Clos network architecture.

3. The method of claim 1, wherein each cell from the group of cells is associated with a common destination address.

4. The method of claim 1, wherein each cell from the group of cells has content associated with at least one data packet.

5. The method of claim 1, wherein a cell from the group of cells has content associated with multiple data packets.

6. The method of claim 1, wherein the group of cells includes more than two cells queued for transmission at the ingress queue, each cell from the group of cells has an equal cell size.

7. The method of claim 1, wherein the sequence value represents a position of the group of cells within the ingress queue.

8. The method of claim 1, wherein the request includes a quantity value corresponding to a number of cells included in the group of cells, the defining includes defining based on the quantity value included in the request.

9. The method of claim 1, wherein the group of cells is a first group of cells, the request includes a quantity value corresponding to a number of cells included in the first group of cells,

the method further comprising:

receiving at the egress schedule module a request to schedule transmission of a second group of cells through the multi-stage switch fabric of the multi-stage switch; and

sending, after a waiting time period defined based on the quantity value associated with the first group of cells, a response associated with the request to schedule transmission of the second group of cells.

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

associate a plurality of cells to define a group of cells based on a destination address associated with each cell from the plurality of cells, the group of cells being queued at an ingress queue associated with an ingress side of a multi-stage switch fabric;

define a request to transmit the group of cells from the ingress side of the multi-stage switch fabric to an egress side of the multi-stage switch fabric, the request including a request sequence value indicating an order of the request with respect to a plurality of requests associated with the ingress queue;

send the request to the egress side of the multi-stage switch fabric; and

receive a response in response to the request, the response including a queue sequence value representing an order within the ingress queue.

11. The non-transitory processor-readable medium of claim 10, wherein the ingress queue is a virtual input queue.

12. The non-transitory processor-readable medium of claim 10, wherein the multi-stage switch fabric has a Clos network architecture.

13. The non-transitory processor-readable medium of claim 10, wherein each cell from the group of cells includes a data sequence value representing an order of content encoded within the group of cells.

14. The non-transitory processor-readable medium of claim 10, further comprising code to:

retrieve at least a portion of the group of cells from a memory based on the queue sequence value such that the portion of the group of cells can be transmitted from the ingress side of the multi-stage switch fabric to the egress side of the multi-stage switch fabric.

15. The non-transitory processor-readable medium of claim 10, further comprising code to:

drop the group of cells from the ingress queue when the response is not received from the egress side of the multi-stage switch fabric within a threshold period of time after the sending of the request.

16. The non-transitory processor-readable medium of claim 10, further comprising code to:

resend the request when the response is not received from the egress side of the multi-stage switch fabric within a threshold period of time after the sending of the request.

17. The non-transitory processor-readable medium of claim 10, further comprising code to:

store, after the defining of the request, the group of cells in a memory location different from the ingress queue.

18. An apparatus implemented in at least one of a memory or a processing device, comprising:

an ingress schedule module associated with an ingress stage of a multi-stage switch fabric, the ingress schedule module to define and send a transmission request having a sequence value associated with a group of cells queued at a line card associated with the ingress stage,

the sequence value representing an order of the group of cells within a plurality of cells queued at the line card and

an egress schedule module associated with an egress stage of the multi-stage switch fabric and to receive the transmission request having the sequence value,

the egress schedule module to send a transmission response having the sequence value to the ingress schedule module in response to the group of cells being scheduled for transmission through a middle stage of the multi-stage switch fabric.

19. The apparatus of claim 18, further comprising:

an ingress queue at the line card associated with the ingress stage, the ingress queue to queue the group of cells.

20. The apparatus of claim 18, further comprising:

an egress port at the egress stage of the multi-stage switch fabric, the egress schedule module to schedule the group of cells for transmission based on a status of the egress port.

21. The apparatus of claim 18, wherein the line card is from a plurality of ingress line cards associated with the ingress stage.

22. The apparatus of claim 18, further comprising:

an ingress queue associated with a priority value, the group of cells being queued at the ingress queue, the ingress schedule module to define the transmission request based on the priority value.

23. The apparatus of claim 18, wherein a boundary of the group of cells is defined based on a boundary associated with a data packet included in the group of cells.

24. The apparatus of claim 18, wherein:

the group of cells is a first group of cells;

the transmission request associated with the first group of cells includes a quantity value corresponding to a number of cells included in the first group of cells;

the egress schedule module is to receive a transmission request associated with a second group of cells queued at the line card associated with the ingress stage of the multi-stage switch fabric, and

the egress schedule module is to send, after a waiting time period defined based on the quantity value associated with the first group of cells, a response associated with the transmission request associated with the second group of cells.