METHODS AND APPARATUS FOR DEFINING A FLOW CONTROL SIGNAL RELATED TO A TRANSMIT QUEUE

• US 20100061390A1
• Filed: 09/11/2009
• Published: 03/11/2010
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Jain, Naveen, Jadav, Abhijeet Sampatrao, Basu, Arghajit, Frailong, Jean-Marc, Sindhu, Pradeep, GODBOLE, Avanindra
• Granted Patent: US 8,213,308 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/267 sent by the destination endpoint network streaming of media packets with control of the source by the destination H04L65/613
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/52 by attributing bandwidth to queues
• CPC Class Codes: H04L 49/9078 using an external memory or storage device

Abstract

In one embodiment, a processor-readable medium can store code representing instructions that when executed by a processor cause the processor to receive a value representing a congestion level of a receive queue and a value representing a state of a transmit queue. At least a portion of the transmit queue can be defined by a plurality of packets addressed to the receive queue. A rate value for the transmit queue can be defined based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue. The processor-readable medium can store code representing instructions that when executed by the processor cause the processor to define a suspension time value for the transmit queue based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue.

Claims

1. A processor-readable medium storing code representing instructions that when executed by a processor cause the processor to:

define a first flow control signal based on a state of a receive queue and a state of a transmit queue, the first flow control signal configured to trigger suspension of transmission, during a suspension time period, of a packet associated with the transmit queue to a memory defining the receive queue, the receive queue and the transmit queue collectively defining at least a portion of a first stage of queues logically nested outside of a second stage of queues;

send the first flow control signal to a transmit side of a link including the transmit queue;

receive an indicator that at least one of the state of the transmit queue or the state of the receive queue has changed; and

send a second flow control signal configured to trigger a change of the suspension time period in response to the indicator.

2. The processor-readable medium of claim 1, wherein the suspension time period is based on a suspension time value included in the first flow control signal,

the processor-readable medium further storing code representing instructions that when executed by the processor cause the processor to:

define a rate value for the transmit queue based on the state of the receive queue and the state of the transmit queue, the rate value for the transmit queue being included in the first flow control signal.

3. The processor-readable medium of claim 1, wherein the first flow control signal is addressed to the transmit queue,

the processor-readable medium further storing code representing instructions that when executed by the processor cause the processor to:

store a value representing a state of a portion of a path between the receive queue and the transmit queue, the first flow control signal being based on the value representing the state of the portion of the path.

4. The processor-readable medium of claim 1, wherein the receive queue is a first receive queue, the packet is a first packet, the suspension time period is based on a first suspension time value included in the first flow control signal,

the processor-readable medium further storing code representing instructions that when executed by the processor cause the processor to:

define a second suspension time value in response to a second packet, different from the first packet, being received at a second receive queue from the transmit queue; and

associate a non-feedback indicator with the second suspension time value when the second suspension time value is less than the first suspension time value.

5. The processor-readable medium of claim 1, wherein the state of the receive queue is a congestion level of the receive queue at a specified time.

6. The processor-readable medium of claim 1, wherein the state of the transmit queue is a flow state of the transmit queue at a specified time.

7. The processor-readable medium of claim 1, wherein the packet is a first packet included in the transmit queue at a first time,

the processor-readable medium further storing code representing instructions that when executed by the processor cause the processor to:

receive a second packet on a receive side of the link at a second time before the first time; and

determine on the receive side of the link the state of the transmit queue based on at least one of the second packet or data associated with the second packet.

8. A processor-readable medium storing code representing instructions that when executed by a processor cause the processor to:

receive a value representing a congestion level of a receive queue and a value representing a state of a transmit queue, at least a portion of the transmit queue being defined by a plurality of packets addressed to the receive queue;

define a rate value for the transmit queue based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue; and

define a suspension time value for the transmit queue based on the value representing the congestion level of the receive queue and the value representing the state of the transmit queue.

9. The processor-readable medium of claim 8, wherein the state of the transmit queue is a flow control state of the transmit queue, the transmit queue is associated with a transmit side of a link, the receive queue is associated with a receive side of the link,

the suspension time value for the transmit queue and the rate value for the transmit queue are sent from the receive side of the link to the transmit side of the physical ink.

10. The processor-readable medium of claim 8, wherein a flow control module associated with the transmit queue is configured to modify transmission of the plurality of packets from the transmit queue based on at least one of the rate value or the suspension time value.

11. The processor-readable medium of claim 8, further storing code representing instructions that when executed by a processor cause the processor to:

receive a value representing a bandwidth available for transmission of a flow control signal, at least one of the suspension time value or the rate value being defined based on the value representing the bandwidth available for transmission of the flow control signal.

12. The processor-readable medium of claim 8, wherein the rate value and the suspension time value are included in a single flow control frame.

13. The processor-readable medium of claim 8, wherein the receive queue is a first receive queue, the plurality of packets is a first plurality of packets addressed to the first receive queue,

the processor-readable medium further storing code representing instructions that when executed by a processor cause the processor to:

receive, at a second receive queue different from the first receive queue, a second plurality of packets from a memory associated with the transmit queue; and

calculate the value representing the state of the transmit queue based on at least one of the second plurality of packets or data associated with the second plurality of packets.

14. The processor-readable medium of claim 8, wherein the suspension time value of the transmit queue is a first suspension time value of the transmit queue,

the processor-readable medium further storing code representing instructions that when executed by a processor cause the processor to:

receive an indicator that at least one of the congestion level of the receive queue or the state of the transmit queue has changed; and

define a second suspension time value of the transmit queue in response to the indicator, the second suspension time value being shorter than the first suspension time value.

15. The processor-readable medium of claim 8, wherein the suspension time value of the transmit queue is a first suspension time value of the transmit queue,

the processor-readable medium further storing code representing instructions that when executed by a processor cause the processor to:

receive an indicator that at least one of the congestion level of the receive queue or the state of the transmit queue has changed during a suspension time period based on the first suspension time value; and

define a second suspension time value of the transmit queue in response to the indicator, the second suspension time value being shorter than the first suspension time value.

16. The processor-readable medium of claim 8, further storing code representing instructions that when executed by the processor cause the processor to:

receive a value representing a state of a feedback path associated with the transmit queue; and

prevent sending of control signal including at least one of the rate value or the suspension time value in response to receiving the value representing the state of the feedback path.

17. An apparatus comprising:

a destination control module configured to define a first flow control signal based on a data flow associated with a first flow control loop, the first flow control loop including a link, a first stage of queues, and a second stage of queues disposed within a transmission path between the link and the first stage of queues, the first flow control signal including a rate value for a transmit queue associated with the first flow control loop and a suspension time value for the transmit queue associated with the first flow control loop,

the destination control module configured to define a second flow control signal based on a data flow within a second flow control loop, the second flow control loop including the second stage of queues and the link, the second flow control loop excluding the first stage of queues.

18. The apparatus of claim 17, wherein the data flow associated with the first flow control loop is from the transmit queue, the destination control module is configured to define a value representing a state of the transmit queue based on the data flow associated with the first flow control loop, the destination control module is configured to define the rate value and the suspension time value based on the value representing the state of the transmit queue.

19. The apparatus of claim 17, wherein at least one of a portion of the first stage of queues or a portion of the second stage of queues are included in an edge device associated with a multi-stage switch fabric.

20. The apparatus of claim 17, wherein the second flow control loop is a priority-based flow control loop.

21. The apparatus of claim 17, further comprising:

the destination control module configured to define a third flow control signal based on a data flow associated with a third flow control loop including the link, the third flow control loop excluding the first stage of queues and the second stage of queues.

22. The apparatus of claim 17, wherein the first stage of queues is logically nested outside of the second stage of queues, the second stage of queues is logically nested outside of the link.