A. Legout

Publications (8)4.27 Total impact

• Source

  Available from: psu.edu

  Article: Revisiting the fair queuing paradigm for end-to-end congestion control

  A. Legout, E.W. Biersack
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  ABSTRACT: Today, the dominant paradigm for congestion control in the Internet is based on the notion of TCP friendliness. To be TCP-friendly, a source must behave in such a way as to achieve a bandwidth that is similar to the bandwidth obtained by a TCP flow that would observe the same round-trip time (RTT) and the same loss rate. However, with the success of the Internet comes the deployment of an increasing number of applications that do not use TCP as a transport protocol. These applications can often improve their own performance by not being TCP-friendly, which severely penalizes TCP flows. To design new applications to be TCP-friendly is often a difficult task. The idea of the fair queuing (FQ) paradigm as a means to improve congestion control was first introduced by Keshav (1991). While Keshav made a fundamental step toward a new paradigm for the design of congestion control protocols, he did not formalize his results so that his findings could be extended for the design of new congestion control protocols. We make this step and formally define the FQ paradigm as a paradigm for the design of new end-to-end congestion control protocols. This paradigm relies on FQ scheduling with per-flow scheduling and longest queue drop buffer management in each router. We assume only selfish and noncollaborative end users. Our main contribution is the formal statement of the congestion control problem as a whole, which enables us to demonstrate the validity of the FQ paradigm. We also demonstrate that the FQ paradigm does not adversely impact the throughput of TCP flows and explain how to apply the FQ paradigm for the design of new congestion control protocols. As a pragmatic validation of the FQ paradigm, we discuss a new multicast congestion control protocol called packet pair receiver-driven layered multicast (PLM).
  IEEE Network 10/2002; · 2.24 Impact Factor
• Article: Bandwidth Allocation Policies for Unicast and Multicast

  A. Legout, J. Nonnenmacher, E.W. Biersack
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  ABSTRACT: Using multicast delivery to multiple receivers reduces the aggregate bandwidth required from the network compared to using unicast delivery to each receiver.
  08/2002;
• Article: Revisiting the Fair Queueing Paradigm for End-to-End Congestion Control

  A. Legout, E.W. Biersack
  [show abstract] [hide abstract]
  ABSTRACT: Today, the dominant paradigm for congestion control in the Internet is based on the notion of TCPfriendliness.
  05/2002;
• Source

  Available from: psu.edu

  Article: Bandwidth-allocation policies for unicast and multicast flows

  A. Legout, J. Nonnenmacher, E.W. Biersack
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  ABSTRACT: Using multicast delivery to multiple receivers reduces the aggregate bandwidth required from the network compared to using unicast delivery to each receiver. However, multicast is not yet widely deployed in the Internet. One reason is the lack of incentive to use multicast delivery. To encourage the use of multicast delivery, we define a new bandwidth-allocation policy, called LogRD, taking into account the number of downstream receivers. This policy gives more bandwidth to a multicast flow as compared to a unicast flow that shares the same bottleneck, without starving the unicast flows, however. The LogRD policy also provides an answer to the question on how to treat a multicast flow compared to a unicast flow sharing the same bottleneck. We investigate three bandwidth-allocation policies for multicast flows and evaluate their impact on both receiver satisfaction and fairness using a simple analytical study and a comprehensive set of simulations. The policy that allocates the available bandwidth as a logarithmic function of the number of receivers downstream of the bottleneck achieves the best tradeoff between receiver satisfaction and fairness
  IEEE/ACM Transactions on Networking 09/2001; 9(4):464-478. · 2.03 Impact Factor
• Source

  Available from: psu.edu

  Article: Beyond TCP-Friendliness: A New Paradigm for End-to-End Congestion Control

  A. Legout, E.W. Biersack
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  ABSTRACT: The dominant paradigm for congestion control in the Internet today is based on the notion of TCP-friendliness.
  10/2000;
• Source

  Available from: psu.edu

  Article: Pathological Behaviors for RLM and RLC

  A. Legout, E.W. Biersack
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  ABSTRACT: RLM [4] and RLC [7] are two well known receiver-driven cumulative layered multicast congestion control protocols. They both represent an indisputable advance in the area of congestion control for multimedia applications. However, there are very few studies that evaluate these protocols, and most of the time, these studies conclude that RLM and RLC perform reasonably well over a broad range of conditions.
  08/2000;
• Source

  Available from: psu.edu

  Article: PLM: Fast Convergence for Cumulative Layered Multicast Transmission Schemes

  A. Legout, E.W. Biersack
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  ABSTRACT: A major challenge in the Internet is to deliver live audio/video content with a good quality and to transfer files to large number of heterogeneous receivers. Multicast and cumulative layered transmission are two mechanisms of interest to accomplish this task efficiently. However, protocols using these mechanisms suffer from slow convergence time, lack of inter-protocol fairness or TCP-fairness, and loss induced by the join experiments. In this paper we define and investigate the properties of a new multicast congestion control protocol (called PLM) for audio/video and file transfer applications based on a cumulative layered multicast transmission. A fundamental contribution of this paper is the introduction and evaluation of a new and efficient technique based on packet pair to infer which layers to join. We evaluated PLM for a large variety of scenarios and show that it converges fast to the optimal link utilization, induces no loss to track the available bandwidth, has inter...
  04/2000;
• Article: Fast Convergence for Cumulative Layered Multicast Transmission Schemes

  A. Legout, E.W. Biersack
  [show abstract] [hide abstract]
  ABSTRACT: A major challenge in the Internet is to deliver live audio/video content with a good quality to large number of receivers. Multicast transmission and cumulative layered transmission are two mechanisms of interest to accomplish this task efficiently. However, protocols using these mechanisms suffer from low convergence time, lack of interprotocol fairness or TCP-fairness, and loss induced by the join experiments. In this paper we define and investigate the properties of a new multicast congestion control protocol for audio /video applications based on a cumulative layered multicast transmission. The protocol uses Packet Pair to discover the available bandwidth. It converges in the order of one second to the optimal link utilization, induces no loss to discover the available bandwidth, has inter-protocol fairness and TCP-fairness, and scales with the number of receivers and the number of sessions. Keywords: Congestion Control, Multicast, Capacity inference, Cumulative layers, Pa...
  12/1999;