Designing a Packet Scheduler for Proportional Delay Differentiation Model

Yi-Hung HUANG  Wang-Hsai YANG  

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.5    pp.1098-1103
Publication Date: 2007/05/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.5.1098
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Network
differentiated services,  proportional delay,  priority queue,  

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We investigate the issues involved in designing a packet scheduler for the proportional delay differentiation (PDD) model in differentiated services (DiffServ) networks. The PDD model controls the average waiting time of each class such that the average waiting time is proportional to its corresponding delay differentiation parameter. This paper proposes a novel packet scheduler for PDD referred to as the longest waiting time first (LWTF). By adding certain conditions, we found that the LWTF scheduler can be reduced to a known packet scheduler-priority queue with linear priorities (PQ-LP). The properties and behaviors of LWTF can be predicted from the analysis of PQ-LP. The simulation results in comparison with other PDD algorithms have also revealed that LWTF provides no worse level of service quality in long timescales and affords more accurate and robust control over the delay ratio in short timescales.