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Improving the Implementation Complexity of the Latency-Optimized Fair Queuing Algorithm

최적 레이턴시 기반 공정 큐잉 알고리즘의 구현 복잡도 개선

  • 김태준 (공주대학교 정보통신공학부) ;
  • 서봉수 (공주대학교 정보통신공학부)
  • Received : 2012.03.01
  • Accepted : 2012.05.31
  • Published : 2012.06.30

Abstract

WFQ(Weighted Fair Queuing) is the most popular fair queuing algorithm to guarantee the Quality-of-Service(QoS), but it has the inherent drawback of a poor resource utilization, particularly under the low rate traffic requiring a tight delay bound. It was recently identified that the poor utilization is mainly due to non-optimized latency of a traffic flow and then LOFQ(Latency-Optimized Fair Queuing) to overcome the drawback was introduced. The LOFQ algorithm, however, renews their optimal latencies for all flows whenever a new flow arrives, which results in the high implementation complexity of O($N^2$).This paper is to reduce thecomplexity to O(1). The proposed method is first to derive the optimal latency index function from the statistical QoS characteristics of the offered load, and then to simply calculate the optimal latency index of the arriving flow using the function.

서비스 품질을 보장하기 위해 널리 사용되는 WFQ(Weighted Fair Queuing)는 엄격한 지연한계를 요구하는 저속 트래픽 흐름의 경우 자원 이용도가 아주 나빠지는 구조적인 한계를 갖고 있다. 이러한 WFQ의 문제점은 최적화 되지 않은 트래픽 흐름의 레이턴시에 기인하는 것으로 밝혀졌고, 최적 레이턴시를 실현하여 자원 이용도를 높일 수 있는 LOFQ(Latency-Optimized Fair Queuing) 가 도입되었다. 그러나 LOFQ는 새로운 흐름을 수락할 때마다 모든 흐름에 대해 최적의 레이턴시를 재 설정해야 하므로 흐름 수락시 O($N^2$)의 복잡도를 가져 구현에 어려움이 있다. 본 논문은 이러한 복잡도를 O(1) 수준으로 낮추는 방식을 제안한다. 제안된 방식은 가해진 트래픽 부하의 서비스 품질의 통계적인 특성을 이용하여 최적 레이턴시 지수 함수를 구한 후 이 함수를 이용하여 도착 흐름의 최적 레이턴시 지수를 간단하게 구하는 것이다.

Keywords

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