Method and apparatus for providing differentiated Quality-of-Service guarantees in scalable packet switches
AssigneeAgere Systems Inc.
InventorsFabio M. Chiussi, Andrea Francini
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Abstract
The invention comprises a method and apparatus for providing differentiated Quality-of-Service (QoS) guarantees in scalable packet switches. The invention advantageously uses a decentralized scheduling hierarchy to regulate the distribution of bandwidth and buffering resources at multiple contention points in the switch, in accordance with the specified QoS requirements of the configured traffic flows.
Claims21
A method for transferring data through a packet switch while providing differentiated Quality-of-Service (QoS) guarantees to respective traffic flows received at individual inputs of the packet switch, the method comprising the steps of:
- storing received data packets associated with said traffic flows in a respective input buffer wherein each respective input buffer resides in an ingress port card and is associated with a particular individual input of the packet switch;
- grouping said traffic flows within a respective input butter on at least a QoS guarantee basis;
- selecting stored data packets for transmission to a switch fabric according to a first plurality of schedulers, each scheduler in the first plurality of schedulers residing in said ingress port cards;
- assigning bandwidth to said selected data packets according to a second plurality of schedulers, each scheduler in the second plurality of schedulers residing in said ingress port cards;
- storing said selected data packets in a plurality of output buffers in said switch fabric, wherein the buffer capacity of the plurality of input buffers exceeds the buffer capacity of said plurality of output buffers;
- adapting the operation of at least one of said first and second schedulers in response to a determination that a utilization level of any output buffer has exceeded a threshold parameter;
- and
- choosing the data packets to be transmitted out of said plurality of output buffers according to a third plurality of schedulers, each scheduler of the third plurality of schedulers residing in said switch fabric.
An apparatus for transferring data packets through a packet switch while providing differentiated Quality-of-Service (QoS) guarantees, comprising:
- a first plurality of schedulers for selecting traffic flows arranged in groups based on a particular packet switch input at which the traffic flows are received and at least a QoS guarantee basis;
- a second plurality of schedulers coupled to said first plurality of schedulers for assigning bandwidth to said selected groups of traffic flows;
- a plurality of input buffers, coupled to said first and second pluralities of schedulers, for holding data packets associated with said grouped traffic flows;
- a third plurality of schedulers, for selecting data packets for transmission to respective output ports;
- a plurality of output buffers, coupled to said third plurality of schedulers, for holding data packets before transmission to said respective output ports, wherein the buffer capacity of said plurality of input buffers exceeds the buffer capacity of said plurality of output buffers;
- and
- a backpressure-signal circuit connected between each of said respective plurality of output buffers and each of said respective plurality of input buffers, transmitting a stop-transmission signal to each of said respective plurality of input buffers when a threshold parameter in any of said respective plurality of output buffers is exceeded.
Dependencies are inferred from the claim text.