Delay-based automatic queue management and tail drop

A method comprising:

• receiving data units in a network device;
• storing data units in one or more buffer memories while the data units await processing by packet-switching logic of the network device;
• utilizing a plurality of queues to manage an order in which the buffered data units are processed by the packet-switching logic;
• calculating a delay measure associated with at least a particular queue of the queues based on an arrival timestamp associated with at least a certain data unit in the particular queue, the delay measure for the particular queue is calculated by subtracting an arrival timestamp of a data unit at the head of the particular queue from a current time, the calculation occurring in response to one or more of:
• dequeuing the data unit at the head of the particular queue, assigning a new data unit to the particular queue, or lapsing of a certain amount of time since the delay measure was last calculated;
• determining one or more policies to apply to particular data units assigned to the particular queue based on the delay measure;
• performing one or more actions indicated by the one or more policies on at least a subset of the particular data units;
• wherein the one or more policies include a tail drop policy that is applicable when the queue delay measure for the particular queue exceeds a tail drop threshold;
• wherein while the tail drop policy is applicable to the particular queue, discarding all data units assigned to the particular queue instead of enqueueing the data units in the particular queue;
• forwarding at least some of the particular data units to other network devices via a plurality of communication interfaces of the network device.

One or more non-transitory computer-readable media storing instructions that, when executed by one or more computing devices, cause performance of:

• receiving data units in a network device;
• storing data units in one or more buffer memories while the data units await processing by packet-switching logic of the network device;
• utilizing a plurality of queues to manage an order in which the buffered data units are processed by the packet-switching logic;
• calculating a delay measure associated with at least a particular queue of the queues based on an arrival timestamp associated with at least a certain data unit in the particular queue, the delay measure for the particular queue is calculated by subtracting an arrival timestamp of a data unit at the head of the particular queue from a current time, the calculation occurring in response to one or more of:
• dequeuing the data unit at the head of the particular queue, assigning a new data unit to the particular queue, or lapsing of a certain amount of time since the delay measure was last calculated;
• determining one or more policies to apply to particular data units assigned to the particular queue based on the delay measure;
• performing one or more actions indicated by the one or more policies on at least a subset of the particular data units;
• wherein the one or more policies include a tail drop policy that is applicable when the queue delay measure for the particular queue exceeds a tail drop threshold;
• wherein while the tail drop policy is applicable to the particular queue, discarding all data units assigned to the particular queue instead of enqueueing the data units in the particular queue;
• forwarding at least some of the particular data units to other network devices via a plurality of communication interfaces of the network device.