How Unfair Can Weighted Fair Queueing Be?



This paper presents a study carried out on a Weighted Fair Queuing implementation for Unix routers - the WFQ implementation of the ALTQ project. It shows the WFQ/ALTQ weaknesses and explains why we cannot expect an interesting behavior from a system using such a scheduler .
The conclusions here presented are supported by a set of tests using UDP traffic only. With a tool developed in our laboratory, we were able to show that changing the classes' weights does not necessarily result on a different Quality of Service for each of the existing classes. To achieve this differentiation, the lengths of the queues which serve the scheduler (one for each class) must be increased beyond reasonable values.
We found that the low-level dynamics of FreeBSD systems practically turns WFQ schedulers useless. The same is applicable to any other work-conserving discipline. Thus, an important conclusion of this paper, is that one must design very carefully the platforms that support work conserving disciplines in order to expect adequate behaviors from those systems, in terms of QoS provision.


QoS fairness


ISCCâ??2000 â?? Fifth IEEE Symposium on Computers and Communications, Antibes, France, 04-06 July 2000, July 2000

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Year 2015 : 1 citations

 Megha Goyal, Yashpal Lather, Vivek Lather, “Modelling & Simulation of Queuing Disciplines Over The N/W Carried Applications (Ftp, Video and Voip) for Traffic Dropped & Time Delay”, International Journal of Computer Science and Mobile Computing, ISSN 2320–088X, Vol. 4, Issue. 1, pg.562 – 570, January 2015.

Year 2012 : 1 citations

 Sukhjit Singh Sehra, Sumeet Kaur Sehra, Navjot Kaur, “Analyzing the Effect of Queuing Disciplines On Network Performance”, International Journal of Computers & Distributed System, Vol 2, No 1, December 2012.

Year 2009 : 1 citations

 Helder Pereira, Andre ? Ribeiro, Paulo Carvalho, "L7 Classification and Policing in the pfSense Platform?, Actas da CRC 2009 - 9ª Conferência sobre Redes de Computadores, Oeiras, Portugal, 15 e 16 de Outubro de 2009.

Year 2006 : 1 citations

 Jiann-Liang Chen, and Nong-Kun Chen, "Feedback Closed-Loop Scheduling Discipline for QoS Guarantee in Mobile Applications? in Wireless Networks, Vol 12, pp. 223"232, Springer Science, 2006.

Year 2004 : 1 citations

 J.-L. Chen and N.-K. Chen, "Feedback Closed-Loop Scheduling Discipline for QoS Guarantee in Mobile Applications? in Proceeding of Parallel and Distributed Computing and Network, (PDCN 2004), Innsbruck, Austria, February 17-19, 2004.

Year 2002 : 2 citations

 Tedi Susanto and Jason Sze, "Smart Queuing: An Adaptive Approach?, High Performance Networks Course Final Project Report, Simon Fraser University, Vancouver, Canada, 2002.

 Tedi Susanto and Jason Sze "Comparison of Queuing Algorithms using OPNET Modeler?: Ensc 835: Network Protocols And Performance, Cmpt 885: Special Topics: High-Performance Networks, Spring 2002.

Year 2001 : 2 citations

 Myung C. Choi, Henry L. Owen, Joachim Sokol, "Packet-Size Based Queuing Algorithm for QoS Support?, Proceedings of the First International Conference on Networking (ICN 2001), P. Lorenz (Ed.), Lecture Notes in Computer Science, Colmar, France, July 9-13, 2001;

 Lisandro Zambenedetti Granville, "Gerenciamento Integrado de Qos em Redes de Computadores?, Tese Submetida à Avaliação, como Requisito Parcial para Obtenção do Grau de Doutor em Ciência da Computação, Universidade Federal do Rio Grande do Sul, Setembro de 2001.