Proportional differentiated services: delay differentiation andpacket scheduling
Dovrolis, C.; Stiliadis, D.; Ramanathan, P.
Networking, IEEE/ACM Transactions on
Volume 10, Issue 1, Feb 2002 Page(s):12 - 26
Digital Object Identifier 10.1109/90.986503
Summary: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
View citation and abstract |
Cart
