Methods and apparatus for flow control associated with a switch fabric

A method, comprising:

• receiving an indicator of an available capacity of an output queue of a multi-stage switch;
• when the available capacity of the output queue is less than a first threshold and greater than a second threshold, receiving a first plurality of data packets from the multi-stage switch at a first rate;
• when the available capacity of the output queue is less than the second threshold, receiving a second plurality of data packets from the multi-stage switch at a second rate greater than the first rate;
• and
• sending a flow control signal to a source edge device from which the first plurality of data packets or the second plurality of data packets entered the multi-stage switch such that the source edge device suspends data transmission to the multi-stage switch to increase the available capacity of the output queue.

An apparatus, comprising:

• a memory;
• and
• a processor operatively coupled to the memory, the processor is configured to:
• send, from an edge device of a multi-stage switch and to an output queue of a stage of the multi-stage switch, a data packet originated from a source peripheral processing device,
• receive a first flow control signal including a first severity value when an available capacity of the output queue meets a first threshold, the first severity value indicating a first level of congestion at the output queue,
• receive a second flow control signal including a second severity value when the available capacity of the output queue meets a second threshold, the second severity value indicating a second level of congestion at the output queue,
• the available capacity of the output queue being greater at the first threshold than at the second threshold, and
• send, to the source peripheral processing device, a third flow control signal based on the first flow control signal or the second flow control signal such that the source peripheral processing device suspends data transmission to the edge device.