Scheduler method and device in a switch

A scheduling device in a switch in which an input data stream is received in an enqueuer means and stored in a number of output queues, the scheduling device selecting data from the output queues to send, and comprising:

• means for setting and keeping an order for polling the queues;
• means for providing and storing a deficit for each queue, the deficit indicating the maximum amount of data which the queue may send;
• means for providing a flag for each queue, the flag indicating if the queue can send data;
• wherein the scheduling device is arranged to set a flag of all queues as a first value (enabled);
• poll all queues in order;
• if the polled queue contains data, refill the deficit value;
• if the deficit value permits, then set a flag of the queue as a second value (active), send data, and decrease the deficit value a corresponding amount for the polled queue, else set a flag of the queue as a third value (disabled);
• if any queue is active after all the queues have been polled, go to a local round, else set a flag of all queues as enabled and start polling the first queue of the order again.

A scheduling method in a switch in which an input data stream is received and stored in a number of output queues, the scheduling method handling the output queues and comprising the steps of:

• polling all queues in order;
• if the polled queue contains data, refill a deficit value indicating a maximum amount of data that may be sent from this queue;
• if the deficit value permits, send data, and decrease the deficit value a corresponding amount for the polled queue, else disable the queue;
• if any queue is permitted to send after all the queues have been polled, go to a local round, else start polling the first queue of the order again.

A scheduling device in a switch in which an input data stream is received in an enqueuer means and stored in a number of output queues, the scheduling device selecting data from the output queues to send, and comprising:

• means for setting and keeping an order for polling the queues;
• means for providing and storing a deficit for each queue, the deficit indicating the maximum amount of data which the queue may send;
• wherein the scheduling device is arranged to;
• poll all queues in order;
• if the polled queue contains data, refill the deficit value;
• if the deficit value permits, then send data, and decrease the deficit value a corresponding amount for the polled queue, else disable the queue;
• if any queue is permitted to send after all the queues have been polled, go to a local round, else start polling the first queue of the order again.