Packet-based traffic shaping

A system for controlling packet-based traffic flow, comprising:

• a plurality of queues configured to hold a plurality of packets until said plurality of packets are forwarded;
• a rate shaper, associated with a queue of said plurality of queues, configured to:
• enable said queue to allow forwarding of a first packet if transmission credit has at least a minimum good credit value;
• reduce said transmission credit by a transmission cost associated with said first packet if said packet is forwarded;
• restore said transmission credit incrementally over time during an idle period to an idle credit value;
• and
• enable said queue to allow forwarding of a second packet made available for forwarding after said idle period when said transmission credit has at least said minimum good credit value;
• and
• a scheduler, coupled to said plurality of queues, that forwards packets from said queue in accordance with a scheduling algorithm if said queue is enabled.

A rate shaper apparatus for use with a scheduler to accomplish rate shaping in a packet-based network, comprising:

• a first register containing a first value corresponding to transmission credit associated with a queue, wherein said first value has an idle credit value after an idle period, and wherein said queue is enabled when said first value has a predetermined minimum good credit value;
• a subtractor for subtracting from said first value a transmission cost associated with a packet dequeued from said queue when said first value has said minimum good credit value, wherein the result of said subtracting is loaded into said first register;
• and
• an adder for adding to said first value a second value corresponding to an amount of credit restored in a time increment, wherein a sum of said adding is loaded into said first register if either another packet is enqueued, or said sum is less than said idle credit value, wherein said first register is set to said idle credit value when said queue is empty and said sum has at least said idle credit value.

A method for packet-based traffic shaping, comprising:

• enabling a queue to allow forwarding of a first packet if transmission credit has at least a minimum good credit value;
• reducing said transmission credit by a transmission cost associated with said first packet if said first packet is forwarded;
• restoring said transmission credit incrementally over time during an idle period to an idle credit value;
• and
• enabling said queue to allow forwarding of a second packet made available for forwarding after said idle period if transmission credit has at least said minimum good credit value.