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Summary: Management of Multi-Queue Switches In QoS
Networks
Yossi Azar Yossi Richter y
Abstract
The concept of Quality of Service (QoS) networks has gained growing attention recently,
as the traÆc volume in the Internet constantly increases, and QoS guarantees are essential to
ensure proper operation of most communication based applications. A QoS switch serves m
incoming queues by transmitting packets arriving at these queues through one output port, one
packet per time unit. Each packet is marked with a value indicating its guaranteed quality
of service. Since the queues have bounded capacity and the rate of arriving packets can be
much higher than the transmission rate, packets can be lost due to insuÆcient queue space.
The goal is to maximize the total value of transmitted packets. This problem encapsulates
two dependent questions: admission control, namely which packets to discard in case of queue
over
ow, and scheduling, i.e. which queue to use for transmission in each time unit. We use
competitive analysis to study online switch performance in QoS based networks. Speci cally, we
provide a novel generic technique that decouples the admission control and scheduling problems.
Our technique transforms any single queue admission control strategy (preemptive or non-
preemptive) to a scheduling and admission control algorithm for our general m queues model,
whose competitive ratio is at most twice the competitive ratio of the given admission control
strategy. We use our technique to derive concrete algorithms for the general preemptive and
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