Methods and apparatus for flow control associated with multi-staged queues

• US 8,154,996 B2
• Filed: 09/30/2008
• Issued: 04/10/2012
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Godbole, Avanindra, Sindhu, Pradeep, Frailong, Jean-Marc
• Primary Examiner(s): Yao, Kwang B
• Assistant Examiner(s): Loo, Juvena
• Application Number:
  US12/242,224
• Publication Number:
  US 20100061238A1
• Time in Patent Office: 1,288 Days
• Field of Search: 370411-417, 370/395.71
• US Class Current: 370/229
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/266 Stopping or restarting the source, e.g. X-on or X-off
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/60 implementing hierarchical scheduling
• CPC Class Codes: H04L 49/505 Corrective measures
• CPC Class Codes: H04L 49/90 Buffering arrangements

Abstract

In one embodiment, a method, comprising receiving at a receive side of a physical link a request to suspend transmission of data from a queue within a transmit side of a first stage of queues and to suspend transmission via a path including the physical link, a portion of the first stage of queues, and a portion of a second stage of queues. The method includes sending, in response to the request, a flow control signal to a flow control module configured to schedule transmission of the data from the queue within the transmit side of the first stage of queues. The flow control signal is associated with a first control loop including the path and differing from a second control loop that excludes the first stage of queues.

Claims

1. A method, comprising:

receiving at a first flow control module at a receive side of a physical link a first request to suspend transmission of a first data from a queue within a transmit side of a first stage of queues and to suspend transmission via a path including the physical link, a portion of the first stage of queues, and a portion of a second stage of queues;

receiving a second request at the first flow control module to suspend transmission of at least a portion of a second data queued at the queue within the transmit side of the first stage of queues;

defining a suspension time value based on the first request and based on the second request, the suspension time value representing a period of time for suspending transmission of the first data and the second data from the queue within the transmit side of the first stage of queues; and

sending from the first flow control module, in response to the first request and the second request, a flow control signal to a second flow control module configured to schedule transmission of the first data from the queue within the transmit side of the first stage of queues, the flow control signal being associated with a first control loop including the path and differing from a second control loop that excludes the first stage of queues, the flow control signal including the suspension time value.

2. The method of claim 1, wherein the second flow control loop is a priority-based flow control loop.

3. The method of claim 1, wherein the physical link is included in a third flow control loop different than the first flow control loop and different than the second flow control loop.

4. The method of claim 1, wherein the first data is queued at the queue within the transmit side of the first stage of queues, the request to suspend transmission includes an identifier associated with the queue within the transmit side of the first stage of queues.

5. The method of claim 1, wherein the queue within the transmit side of the first stage of queues is included in a plurality of transmit queues included in the first stage of queues, the portion of the second stage of queues includes a transmit queue, the plurality of transmit queues included in the first stage of queues fans into the transmit queue included in the second stage of queues.

6. The method of claim 1, wherein the queue within the transmit side of the first stage of queues is a virtual queue, the flow control signal includes an identifier associated with the virtual queue.

16. The method of claim 1, wherein the suspension time value is an average of a time period associated with the first request and a time period associated with the second request.

17. The method of claim 1, wherein the suspension time value is a time period associated with the first request when a time period associated with the first request is greater than a time period associated with the second request.

18. The method of claim 1, wherein the defining is delayed for a wait time period, the receiving the first request and the receiving the second request being within the wait time period.

19. The method of claim 1, wherein the flow control signal is a first flow control signal, the method further comprising:

storing an indication of the first flow control signal;

receiving a third request at the first flow control module to suspend transmission of at least a portion of a third data queued at the queue within the transmit side of the first stage of queues; and

determining to not send a second flow control signal based on the suspension time value and the indication of the first flow control signal.

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

include an identifier of a transmit queue within a data packet received at the transmit queue, the transmit queue being disposed on a transmit side of a physical link;

send the data packet to a receive queue via a transmission path that includes the transmit queue, the physical link, the receive queue, and a pair of queues disposed within the transmission path between the receive queue and the transmit queue;

receive from a receive side of the physical link a first flow control signal defined in response to the data packet being received at the receive queue, the first flow control signal including the identifier of the transmit queue and a first suspension time value associated with the identifier of the transmit queue;

receive from the receive side of the physical link a second flow control signal including a second suspension time value associated with the identifier of the transmit queue; and

define a third suspension time value based on the first suspension time value and the second suspension time value.

8. The processor-readable non-transitory medium of claim 7, wherein the transmit queue and the receive queue are included in a first stage of queues, the pair of queues is included in a second stage of queues mutually exclusive from the first stage of queues.

9. The processor-readable non-transitory medium of claim 7, wherein the transmit queue and the receive queue are included in a first stage of queues, the pair of queues is included in a second stage of queues mutually exclusive from the first stage of queues, the flow control priority is included in a first plurality of flow control priorities associated with the second stage of queues, the first stage of queues is associated with a second plurality of flow control priorities different than the first plurality of flow control priorities.

10. The processor-readable non-transitory medium of claim 7, wherein the transmit queue is included in a plurality of transmit queues that fan into a queue from the pair of queues, the first flow control signal and the second flow control signal are configured to trigger suspension of data transmissions from less than all transmit queues included in the plurality of transmit queues.

11. A method, comprising:

receiving a first request to suspend transmission of a first data queued at a first stage of queues, the request associated with the first data being defined based on an availability of a first receive queue included in the first stage of queues, the first data being queued for transmission via a transmission path including a physical link and a portion of a second stage of queues disposed within the transmission path between the physical link and the first stage of queues, the second stage of queues including a transmit queue;

receiving a second request to suspend transmission of a second data queued at the first stage of queues, the request associated with the second data being defined based on an availability of a second receive queue included in the first stage of queues, the second data being queued for transmission via the transmission path; and

defining a flow control signal based on the first request and based on the second request, configured to trigger suspension of transmission of at least one of the first data or the second data such that data flow via the transmit queue included in the second stage is modified.

12. The method of claim 11, wherein the first data is queued at a transmit queue included in the first stage of queues, the second data is queued at the transmit queue included in the first stage of queues, the defining includes defining a suspension time value for the transmit queue included in the first stage of queues based on the first request and based on the second request.

13. The method of claim 11, wherein the defining includes defining a suspension time value, the suspension time value is encoded in the flow control signal based on a layer-2 protocol.

14. The method of claim 11, wherein the first request includes a first suspension time value, the second request includes a second suspension time value different than the first suspension time value, the defining being performed in response to a condition associated with a comparison of the first suspension time value and the second suspension time value being satisfied.

15. The method of claim 11, wherein the second stage of queues is a flow-controllable stage of queues, the physical link is a flow-controllable link.