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Quality of Service Routing: A Performance Perspective
George Apostolopoulos (University of Maryland), Roch Guérin (IBM), Sanjay Kamat (IBM), Satish K. Tripathi (UC Riverside)
Recent studies provide evidence that Quality of Service (QoS) routing
can provide increased network utilization compared to routing that is
not sensitive to QoS requirements of traffic. However, there are still
strong concerns about the increased cost of QoS routing, both in terms
of more complex and frequent computations and increased routing
protocol overhead. The main goals of this paper are to study these two
cost components, and propose solutions that achieve good routing
performance with reduced processing cost. First, we identify the
parameters that determine the protocol traffic overhead, namely (a)
policy for triggering updates, (b) sensitivity of this policy, and (c)
clampdown timers that limit the rate of updates. Using simulation, we
study the relative significance of these factors and investigate the
relationship between routing performance and the amount of update
traffic. In addition, we explore a range of design options to reduce
the processing cost of QoS routing algorithms, and study their effect
on routing performance. Based on the conclusions of these studies, we
develop extensions to the basic QoS routing, that can achieve good
routing performance with limited update generation rates. The paper
also addresses the impact on the results of a number of secondary
factors such as topology, high level admission control, and
characteristics of network traffic.
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