Event-based shaper for a packet switch

摘要

Egress of data packets from a packet switch is controlled in a manner that involves adjusting the shaper accumulators only when a packet egress event or accumulator credit threshold event occurs. A timeline having a number of timeslots is maintained in a memory to mark the times at which events are predicted to occur. If an egress event occurs, in which one or more data packets have been sent from a queue, or if the current timeslot contains a marker, then a count stored in an accumulator is adjusted. If an egress event has occurred or a threshold event in which a count stored in an accumulator has crossed a threshold has occurred, then a marker is stored in a future timeslot.

主权项

1. A method for controlling egress of data packets from a packet switch having a plurality of queues and a plurality of accumulators, each accumulator corresponding to one of the queues, the method comprising:
controlling egress of data packets from the plurality of queues in response to counts stored in the plurality of accumulators; maintaining a timeline in a memory, the timeline comprising a plurality of sequential timeslots including a current timeslot representing a current time and a plurality of future timeslots representing future times; determining if an egress event has occurred in which one or more data packets have been sent from a queue; determining if the current timeslot contains a marker; adjusting a count stored in an accumulator if it is determined that an egress event has occurred or if it is determined that the current timeslot contains the marker; determining if a threshold event has occurred in which a count stored in an accumulator has crossed a threshold; and storing a marker in a future timeslot if it is determined that an egress event or a threshold event has occurred.