Active Queue Management Performance Research Articles

Nonlinear performance evaluation model for throughput of AQM scheme using full factorial design approach

SummaryThe performance of active queue management (AQM) is measured in terms of throughput, delay, queue size, and loss rate. We have carried out the optimized performance measure of throughput for AQM scheme random early detection (RED) using full factorial design (FDD) technique that is a new approach of performance analysis particularly for congestion control algorithms. We have considered the input factors, viz, buffer size, maximum threshold, and the number of file transfer protocol (FTP) sources for the evaluation of RED that can be used for other AQM schemes, viz, adaptive RED, three‐section RED (TRED), and adaptive queue management with random dropping (AQMRD). The effect of each input factor as well as their interactions are evaluated using factorial design technique that results to obtain the nonlinear equation for performance measure in terms of input factors buffer size, maximum threshold, and the number of FTP sources. Finally, we show the contour plots for variation of performance measure throughput (steady state) from minimum to maximum values with respect to the different setting of input parameters.

On fairness and application performance of active queue management in broadband cable networks

We evaluate the performance of modern delay-based active queue management (AQM) algorithms in downstream DOCSIS 3.0 cable environments. Our simulation-based study involves scenarios that include tiered service levels and application workloads that include FTP, HTTP-based adaptive streaming (HAS), VoIP, and web traffic.Our results show that AQM maintains target queuing delays and consequently provides strong isolation between responsive high bandwidth and low bandwidth latency sensitive flows. We also show that lowering target queuing delays exacerbates TCP’s RTT unfairness. Nevertheless, in the scenarios that we studied, observed application performance was not significantly impacted by the specific AQM in use.With the potential large deployment of AQM imminent for DOCSIS 3.0, the analysis presented in this paper provides timely feedback to the community concerning how delay-based AQM can manage bandwidth allocation fairness and application performance in realistic downstream DOCSIS 3.0 cable network systems.

Model Integrating Fuzzy Argument with Neural Network Enhancing the Performance of Active Queue Management

The bottleneck control by active queue management mechanisms at network nodes is essential. In recent years, some researchers have used fuzzy argument to improve the active queue management mechanisms to enhance the network performance. However, the projects using the fuzzy controller depend heavily

Active Queue Management of TCP Flows with Self-scheduled Linear Parameter Varying Controllers

Control-theoretic approaches to Active Queue Management (AQM) are typically based on linearizations of fluid flow models around design conditions. These conditions depend on the Round Trip Time (RTT), and the AQM performance is known to degrade if RTT values during actual operation depart substantially from design values. To overcome this difficulty a self-scheduled LPV controller for AQM is considered in this paper, where the controller is modified in real-time based on RTT. Simulations show that the self-scheduled LPV controller has good performance for both constant and time-varying RTTs, and outperforms two other common control-theoretic approaches to AQM.

Using interval phase margin assignment to self-tune a PI AQM controller for TCP traffic

We propose a self-tuning PI (Proportional-Integral) controller for an AQM (Active Queue Management) router supporting TCP traffic in the Internet. Classical control theory is applied in the controller design to meet the phase margin specification in the frequency domain. By assigning a proper interval of the phase margin, we can achieve good AQM performance by making the control system adapt to dramatic load changes. Our self-tuning PI controller self-tunes only when there is a great change in the network environment that would cause the phase margin of the AQM control system to drift outside the specified interval. Based on the knowledge of the queue size, our PI controller can regulate the TCP source window size by adjusting the packet drop probability, thus clamping the steady queue size around a desirable target buffer occupancy. We demonstrate by OPNET® simulations that with our self-tuning PI controller applied, the network exhibits a good transient behavior. A simple PID (Proportional-Integral-Derivative) controller design method is also provided.

Performance analysis of buffer allocation schemes under MMPP and Poisson traffic with individual thresholds

Various buffer management and congestion control mechanisms have been proposed to support differentiated Quality-of-Service (QoS) requirements due to the heterogeneous properties of real-world network traffic and applications. Active Queue Management (AQM) with multiple thresholds, which starts dropping packets before the queue becomes full in order to notify incipient stages of congestion, is a promising buffer allocation mechanism. With the aim to capture the effects of heterogeneous traffic and justify the choice of appropriate parameters, this paper develops an original analytical model for a finite buffer queueing system with AQM under two heterogeneous classes of traffic which are modelled, respectively, by the non-bursty Poisson Process and bursty Markov-Modulated Poisson Process (MMPP). We derive the aggregated and marginal performance metrics including the mean queue length, response time, utilization, throughput, and loss probability. Extensive simulation experiments are used to validate the accuracy of the analytical model. Furthermore the model is adopted to evaluate the performance of AQM with heterogeneous traffic and under different working conditions.

Self-tuning TCP traffic controller using gain margin specification

The paper proposes a self-tuning active queue management (AQM) controller for Internet protocol (IP) routers supporting transmission control protocol (TCP) traffic in the Internet. Classical control theory is applied in the design to meet the frequency-domain-specification gain margin. The user can assign a proper gain margin to achieve good AQM performance. Simple equations for obtaining the AQM controller are derived. The designed AQM controller self-tunes, only when changes in Internet traffic have drifted the traffic monitoring parameter outside its specified interval, otherwise the self-tuning AQM controller remains unchanged. The OPNET® simulations used by the authors in single and in multiple bottleneck links demonstrate that, with the use of a self-tuning AQM controller in the routers, this AQM control system adapts very well to great fluctuations in the TCP traffic, thus providing the network with good stability robustness.

Design of an adaptive PI rate controller for streaming media traffic based on gain and phase margins

An adaptive proportional-integral (PI) rate controller for best-effort streaming media traffic in the Internet is proposed. Classical control theory is employed in the control design, which allows the user to achieve good performance of active queue management (AQM) in the router by specifying the proper gain and phase margins. The proposed adaptive PI rate controller will self-tune only when the number of active controlled source nodes changes or the average round trip time becomes longer. The adaptive PI rate controller located in the router can calculate the advertised source transmission rate for the streaming media traffic based on the instantaneous queue length of the buffer, which clamps the steady value of the queue length around the target buffer occupancy. Every controlled source node always transmits streaming media traffic through IP packets into the network at the maximum allowed transmission rate, thus providing the best-effort service traffic and maximising the bandwidth utilisation of the Internet. Our OPNET simulations demonstrate that the rate-based AQM control system can adapt to the fluctuation of the uncontrolled guaranteed traffic very well, thus providing the network with good stability robustness.

Adaptive AQM controllers for IP routers with a heuristic monitor on TCP flows

We propose adaptive proportional (P) and proportional-integral (PI) controllers for Active Queue Management (AQM) in the Internet. We apply the classical control theory in the controller design and choose a proper phase margin to achieve good performance of AQM. We have identified a simple heuristic parameter that can monitor the changes of network environment. Our adaptive controllers would self-tune only when the dramatic change in the network parameters drift the monitoring parameter outside its specified interval. When compared to P controller, a PI controller has the advantage of regulating the TCP source window size by adjusting the packet drop probability based on the knowledge of instantaneous queue size, thus steadying the queue size around a target buffer occupancy. We have verified our controllers by OPNET simulation, and shown that with an adaptive PI controller applied, the network is asymptotically stable with good robustness. Copyright © 2005 John Wiley & Sons, Ltd.

A stable queue-based adaptive controller for improving AQM performance

Active queue management (AQM) mechanisms are designed to provide better support for end-to-end congestion control mechanisms of transmission control protocol (TCP) in TCP/IP networks. This paper introduces a stable queue-based adaptive proportional–integral (Q-SAPI) controller for AQM and presents an implementation. The starting points of our approach are the recently developed fluid-flow modeling and control theoretic interpretation of the TCP/AQM dynamics, and the recently developed fixed-gain proportional–integral (PI) controller for AQM. Q-SAPI aims to improve the transient performance of the fixed-gain PI controller while maintaining its steady-state performance over a wide range of uncertainties in round-trip time (RTT) and the number of active TCP flows. The robustness of Q-SAPI is studied in detail, which provides guidelines for selecting control parameters. Through extensive simulations, we demonstrate the ability of Q-SAPI in controlling queue length in both transient and steady states. Q-SAPI achieves this by adapting the controller gains according to the queue length.

On Designing Self-Tuning Controllers for AQM Routers Supporting TCP Flows Based on Pole Placement

This paper revisits the simple pole placement technique in the classical control theory, and exploits this technique to propose two kinds of controllers for active queue management (AQM) in Internet protocol (IP) routers: the self-tuning proportional controller based on pole placement (ST/spl I.bar/P/spl I.bar/PP) and the self-tuning proportional-plus-integral controller based on pole placement (ST/spl I.bar/PI/spl I.bar/PP). The damping ratio /spl xi/ and undamped natural frequency /spl omega//sub n/ can be appropriately chosen such that: 1) the transient response performance of the system is satisfied and 2) all the poles would lie in the left-half s-plane to guarantee the stability of the control system. The self-tuning controllers can assign proper intervals of /spl xi/ and /spl omega//sub n/ to achieve good AQM performance and thereby adapting the system to significant load changes very well. Furthermore, the ST/spl I.bar/PI/spl I.bar/PP controller can regulate the packet drop probability based on the knowledge of the instantaneous queue size, and clamp the steady value of the queue length to a specified reference value. We verify the effectiveness of these two controllers via OPNET simulation. Our simulation results show the following: 1) choosing appropriate /spl xi/ and /spl omega//sub n/ can successfully satisfy the transient response of the system and 2) when the network load changes, the ST/spl I.bar/P/spl I.bar/PP controller and the ST/spl I.bar/PI/spl I.bar/PP controller exhibit extremely short settling time.

Improving the performance of active buffer management with per-flow information

This letter proposes a new technique to improve the performance of active queue management (AQM) with per-flow information such as balanced random early detection (BRED). The technique is virtual buffer occupancy, which represents not the actual buffer occupancy but the buffer occupancy as it would be if packets were serviced in a fair round robin fashion. In AQM using virtual buffer occupancy, packets of flow i are dropped based on the virtual buffer occupancy of flow i. We show that BRED using virtual buffer occupancy achieves fairer bandwidth allocation than original BRED.