Nortel Networks Corporation

Other

Marty Borden

Nanying Yin

Victor Firoiu

Shiping Li

Michael G Hluchyj

Michael Hluchyj

A method, apparatus, and computer program product for modeling dynamics of a queue are disclosed. A queue law function can be used to determine a control function for use in a congestion control module in a network for dropping packets. A queue law function may be determined based upon traffic conditions in the network. First a quantity that is representative of the link utilization between first and second nodes is determined. If the link is fully utilized, a quantity that is representative of an average round transmission trip time for data to be sent from the first node to the second node and an acknowledgment to be received by the first node is calculated. The queue law function which is dependent on a data drop probability based upon the link utilization, the buffer size, and the average round trip transmission time is determined. From this queue law function, parameters for defining a control function can be derived. These parameters include the minimum buffer size and the maximum expected queue size during normal operation for the node.

Method and apparatus for queue modeling

A method, apparatus, and computer program product for determining a drop probability for use in a congestion control module located in a node in a network is disclosed. A weight value for determining a weighted moving average of a queue in a node is first systematically calculated. The weighted moving average is calculating and an average queue size for the node is determined based upon the weighted moving average. A control function associated with the congestion control module is evaluated using the average queue size to determine the drop probability. In a further embodiment, the control function is calculated based upon a queue function where the queue function is calculated based upon predetermined system parameters. Thus, when the congestion control module drops packets based upon the drop probability determined by the control function the queue will not oscillate.

Method and apparatus for queue management

To determine when to service a cell queue in an ATM network, a cell scheduler can use an ideal service interval time. The ideal service interval time of each cell queue is the reciprocal of the bandwidth assigned to that cell queue. An interval based cell scheduler is then initialized by setting a time reference to zero and setting a next service time for each queue to the queue's ideal service interval. The cell scheduler then enters a repeating loop. During each iteration of the loop, the first nonempty cell queue having the smallest next service time value is selected. The selected queue is serviced and its next service time is updated by adding its ideal service interval. The time reference value is also updated. If all the queues are empty, then an idle time slot is allowed to pass. The cell queues may consists of queue groups. For example, several queues can be gathered into a queue group that assigned a single ideal service time. Within this queue group, each queue may be serviced equally using a fair queuing system.

Queue service interval based cell schedular with hierarchical queuing configurations

Queue service interval based cell scheduler with hierarchical queuing

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Littleton, MA, United States of America

Marty Borden