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

• US 9,077,466 B2
• Filed: 12/03/2012
• Issued: 07/07/2015
• 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): EBRAHIM, ANEZ C
• Application Number:
  US13/692,425
• Publication Number:
  US 20130121343A1
• Time in Patent Office: 946 Days
• US Class Current: 1/1
• 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. An apparatus, comprising:

an egress schedule module implemented in at least one of a memory or a processing device, the egress schedule module configured to receive, from an ingress schedule module associated with an ingress stage of a multi-stage switch fabric, a request to schedule transmission of a group of cells from an ingress queue, the group of cells including at least two cells, the request including a sequence value representing an order of the group of cells within a plurality of cells in the ingress queue, the egress schedule module being associated with an egress stage of the multi-stage switch fabric,

the egress schedule module configured to define, in response to the request, a response including the sequence value when an egress port associated with the egress stage of the multi-stage switch fabric is available to transmit the group of cells, the egress schedule module configured to send the response to the ingress schedule module.

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

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

4. The apparatus of claim 1, wherein the request includes a quantity value corresponding to a number of cells included in the group of cells, the egress schedule module configured to define the response based on the quantity value included in the request.

5. The apparatus 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 egress schedule module configured to receive a request to schedule transmission of a second group of cells,

the egress schedule module configured 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 request to schedule transmission of the second group of cells.

6. An apparatus, comprising:

an ingress schedule module implemented in at least one of a memory or a processing device, the ingress schedule module configured to define a transmission request having a sequence value associated with a group of cells queued at an ingress queue associated with an ingress stage of a multi-stage switch fabric, the group of cells including at least two cells, the sequence value representing an order of the group of cells within a plurality of cells queued at the ingress queue, the ingress schedule module being associated with the ingress stage of the multi-stage switch fabric,

the ingress schedule module configured to send the transmission request to an egress schedule module associated with an egress stage of the multi-stage switch fabric,

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

7. The apparatus of claim 6, wherein the group of cells is a first group of cells, the ingress schedule module configured to define a transmission request for a second group of cells queued at the ingress queue,

the ingress schedule module configured to send the transmission request for the second group of cells to the egress schedule module,

the ingress schedule module configured to drop the second group of cells from the ingress queue when a response associated with the second group of cells is not received at the ingress schedule module within a threshold period of time after sending of the transmission request for the second group of cells from the ingress schedule module.

8. The apparatus of claim 6, wherein the group of cells is a first group of cells,

the ingress schedule module configured to define a transmission request for a second group of cells queued at the ingress queue,

the ingress schedule module configured to send the transmission request for the second group of cells to the egress schedule module,

the ingress schedule module configured to resend the transmission request for the second group of cells when a response associated with the second group of cells is not received at the ingress schedule module within a threshold period of time after sending of the transmission request for the second group of cells from the ingress schedule module.

9. The apparatus of claim 6, wherein the ingress schedule module is configured to store, after defining the transmission request, the group of cells in a memory location different from the ingress queue.

10. The apparatus of claim 6, wherein the ingress queue implemented at a line card associated with the ingress stage.

11. The apparatus of claim 6, wherein the ingress queue is associated with a priority value, the ingress schedule module configured to define the transmission request based on the priority value.

12. A method, comprising:

defining a group of cells from a plurality of cells based on a position of the group of cells in the plurality of cells and a common destination address associated with each cell from the group of cells, the group of cells being mutually exclusive from the remaining cells from the plurality of cells, the common destination address associated with the group of cells being different from a destination address associated with at least one cell from the remaining cells, the plurality of cells being queued at an ingress queue associated with an ingress side of a multi-stage switch fabric;

defining 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 sequence value associated with the group of cells, the sequence value being a queue sequence value representing an order of the group of cells within the plurality of cells;

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

receiving a response in response to the group of cells being scheduled for transmission from the ingress side of the multi-stage switch fabric to the egress side of the multi-stage switch fabric, the response being a delayed response if destination port availability criteria are not met.

13. The method of claim 12, wherein each cell from the group of cells has content associated with at least one data packet.

14. The method of claim 12, wherein a cell from the group of cells has content associated with multiple data packets.

15. The method of claim 12, wherein each cell from the group of cells has an equal cell size.

16. The method of claim 12, wherein each cell from the group of cells includes a data sequence value representing an order of content encoded within the group of cells.

17. The method of claim 12, further comprising:

retrieving at least a portion of the group of cells from a memory 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.

18. The method of claim 12, 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.

19. A method, comprising:

defining a group of cells from a plurality of cells based on a position of the group of cells in the plurality of cells and a common destination address associated with each cell from the group of cells, the group of cells being mutually exclusive from the remaining cells from the plurality of cells, the common destination address associated with the group of cells being different from a destination address associated with at least one cell from the remaining cells, the plurality of cells being queued at an ingress queue associated with an ingress side of a multi-stage switch fabric;

defining 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 includes a sequence value associated with the group of cells, the sequence value being a request sequence value indicating an order of the request with respect to a plurality of requests defined at the ingress side of the multi-stage switch fabric;

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

receiving a response in response to the group of cells being scheduled for transmission from the ingress side of the multi-stage switch fabric to the egress side of the multi stage switch fabric, the response being a delayed response if destination port availability criteria are not met.