Proportional Differentiated Services: Delay Differentiation and Packet Scheduling

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Proportional Differentiated Services: Delay Differentiation and Packet Scheduling (1999)

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by Constantinos Dovrolis , Dimitrios Stiliadis , Parameswaran Ramanathan

Venue:	IEEE/ACM Transactions on Networking
Citations:	188 - 6 self

BibTeX

@INPROCEEDINGS{Dovrolis99proportionaldifferentiated,
    author = {Constantinos Dovrolis and Dimitrios Stiliadis and Parameswaran Ramanathan},
    title = {Proportional Differentiated Services: Delay Differentiation and Packet Scheduling},
    booktitle = {IEEE/ACM Transactions on Networking},
    year = {1999},
    pages = {109--120}
}

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Abstract

The proportional differentiation model provides the network operator with the `tuning knobs' for adjusting the per-hop quality-of-service (QoS) ratios between classes, independent of the class loads. This paper applies the proportional model in the differentiation of queueing delays, and investigates appropriate packet scheduling mechanisms. Starting from the proportional delay differentiation (PDD) model, we derive the average queueing delay in each class, show the dynamics of the class delays under the PDD constraints, and state the conditions in which the PDD model is feasible. The feasibility model of the model can be determined from the average delays that result with the strict priorities scheduler. We then focus on scheduling mechanisms that can implement the PDD model, when it is feasible to do so. The proportional average delay (PAD) scheduler meets the PDD constraints, when they are feasible, but it exhibits a pathological behavior in short timescales. The waiting time priority (WTP) scheduler, on the other hand, approximates the PDD model closely, even in the short timescales of a few packet departures, but only in heavy load conditions. PAD and WTP serve as motivation for the third scheduler, called hybrid proportional delay (HPD). HPD approximates the PDD model closely, when the model is feasible, independent of the class load distribution. Also, HPD provides predictable delay differentiation even in short timescales.

Keyphrases

pdd model delay differentiation packet scheduling proportional differentiated service short timescales pdd constraint proportional average delay tuning knob packet departure third scheduler average queueing delay predictable delay differentiation average delay pathological behavior network operator hybrid proportional delay heavy load condition feasibility model class load time priority class load distribution per-hop quality-of-service proportional differentiation model proportional model proportional delay differentiation strict priority scheduler appropriate packet

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