A Non-Work-Conserving Scheduler to Provide Proportional Delay Differentiated Services and Best Effort Service

Yuan-Cheng LAI
Arthur CHANG

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B    No.9    pp.2493-2502
Publication Date: 2006/09/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.9.2493
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
Keyword: 
proportional delay differentiation,  non-work conserving,  best effort,  media synchronization,  

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Summary: 
The proportional delay differentiation (PDD) model provides consistent packet delay differentiation between classes of service. Currently, the present schedulers performing the PDD model cannot achieve desired delay proportion observed in short timescales under light/moderate load. Thus, we propose a Non-Work-Conserving (NWC) scheduler, which utilizes the pseudo-waiting time for an empty queue and forces each class to compare its priority with those of all other classes. Simulation results reveal that NWC outperforms all current schedulers in achieving the PDD model. However, NWC suspends the server from transmitting packets immediately if an empty class has the maximum priority, resulting in an idle server. Therefore, we further propose two approaches, which will serve a best-effort class during this idle time. Compared with other schedulers, the proposed approaches can provide more predictable and controllable delay proportion, accompanied with satisfactory throughput and average queuing delay.