Characterization of long-range dependent traffic regulated by leaky-bucket policers and shapers

摘要

Long-range dependence (LRD) is a widely verified property of Internet traffic, which severely affects network queuing performance. An approach for guaranteeing quality-of-service requirements is enforcing the statistical profile of input traffic by policing or shaping regulators. In this paper, it is investigated by thorough simulation how leaky-bucket (LB) policers and shapers affect the LRD of regulated traffic having 1/f~α power spectral density. Unlike previous studies on this subject, spectral analysis of regulated traffic and estimation of its LRD parameter α are carried out in the time domain using the Modified Allan Variance, because of its demonstrated superior accuracy in LRD parameter estimation. Adoption of this tool allows to attain unprecedented precision and fineness in characterizing the LRD of LB regulated traffic. In addition, the probability that LRD traffic is dropped by policers or that it exceeds a delay limit in shapers is also studied. The queuing behaviour of LRD regulated traffic in FIFO schedulers is finally investigated, highlighting conditions under which a service level agreement based on delay bounds can be violated by varying α in input LRD traffic, even if this is controlled by policers or shapers.