Implementation and Evaluation of Proportional Integral Controller Enhanced (PIE) Algorithm in ns-3

Proportional Integral controller Enhanced (PIE) is an Active Queue Management (AQM) mechanism to address the bufferbloat problem. AQM mechanisms tackle bufferbloat by dropping or marking packets before the buffers fill up, but typically do not ensure fairness between responsive and unresponsive flows that share the same bottleneck link i.e., unresponsive flows can starve responsive flows when they co-exist. Recently, there has been an active interest in integrating flow protection mechanisms with AQM mechanisms to collectively tackle the problem of bufferbloat and fairness. There exist two such algorithms: Flow Queue Controlled Delay (FQ-CoDel) and Flow Queue Proportional Integral Controller Enhanced (FQ-PIE) that integrate flow protection with AQM mechanisms. Flow protection is achieved by dividing the incoming flows into separate queues and then applying CoDel/PIE algorithm on respective queues. Although FQ-CoDel is available in the mainline of Linux, there does not exist a model for FQ-PIE. In this paper, we discuss the design and implementation of FQ-PIE in the Linux kernel. We test and evaluate our proposed model of FQ-PIE in different scenarios by comparing the results obtained from it to those obtained for PIE and FQ-CoDel. Besides evaluating the fairness among responsive and unresponsive flows, we also evaluate the fairness among different types of responsive flows, such as when CUBIC TCP shares the same bottleneck link as TCP BBR. We also assess the benefits of integrating flow protection with AQM mechanisms in terms of reducing the latency for thin, latency sensitive flows when they coexist with thick, latency tolerant flows.

In this paper we compare the three Active Queue Management (AQMs) Adaptive Random Early Detection (ARED), Controlled Delay (CoDel) and Proportional Integral controller Enhanced (PIE) in static as well as dynamic scenarios. We find significant issues when these algorithms are used for big Round Trip Times (RTTs) as well as a significant utilization decrease when used for high bandwidth links. When used for low and medium sized links, CoDel, PIE and ARED are suitable alike, but for corner scenarios clear recommendations can be given.

In the recent years, the bufferbloat phenomenon was observed which is mainly due to oversized unmanaged buffers in the Internet. This triggered a new discussion of active queue management (AQM) algorithms in the IETF. Controlled Delay (CoDel) and Proportional Integral controller Enhanced (PIE) are considered as an alternative to Random Early Detection (RED). Their intention is both to take advantage of large buffers for occasional bursts and to limit queueing delays most of the time. Moreover, they are able to cope with varying bandwidth. In this paper, we study the performance of CoDel, PIE, and CoDel-ACT, which is an effective modification of CoDel that leads to better performance than CoDel in our studies. We experiment with saturated TCP sources and a fixed-bandwidth bottleneck link and focus on the delay-limiting phase of the algorithms. We investigate the impact of configuration parameters and traffic load on link utilization and queueing delay. We study the timely evolution of queuing delays and drop patterns, and point out significant differences among the algorithms. In particular, we show that CoDel's drop behavior changes over time and may lead to underutilization.

In this paper, we describe active queue management (AQM) mechanisms that are employed in the Internet protocol (IP) routers. We address the functionality and implementation of AQM blocks in IP routers. We also describe the benefits of the AQM mechanisms and justify the need for their implementation. Simulation results illustrate the fairness and the efficient use of resources in networks with the AQM support.

Last decade seen an astronomical growth in the development of the multi-hop wireless technologies such as mobile ad-hoc network, vehicular ad-hoc network and cognitive radio network, the network congestion poses a serious threat in full scale deployment of wireless multi-hop technologies towards internet architecture. An active queue management (AQM) is a proactive, effective congestion control mechanism deployed at the intermediate gateway. Random Early Detection (RED) is the earliest and most widely used Active Queue Management (AQM) mechanism in backbone gateways, which in turn reduce global synchronization and bias against burst traffic. The traditional RED and its variants such GRED, AGRED, ARED, NL-RED, REM, RIO, etc. has more parameters to be tuned each time for the arrival of the packet. The tuning of more parameters leads to computation load, so it is unsuitable for low memory less devices such as laptops, handset, etc. In this paper, a micro level analysis was made on standard AQM's under multi-hop wireless environment. The results were analyzed based on the metrics such as average queue length, packet loss, queuing delay, end to end delay and throughput. This work forms a base work in designing a new queuing algorithm over heavily tailed multi-hop networks.

AQM (Active Queue Management) is an effective scheme to enhance congestion control. Most of the mobile networks today use queue management to manage and improve network performance. In this paper, we deploy AQM mechanism in Mobile Ad Hoc networks to manage the packets queue in the network nodes. By modeling a node with multi-receiver in Ad Hoc networks, we develop an analytical model for a multi-server and finite capacity queuing system with AQM mechanisms under multi-classes of traffic. We consider multiple classes of traffic modeled by Poisson arrival and exponentially service processes. It deduced the performance metrics including the average queue length, system throughput, probability of drop packet and the average waiting time. Then, it illustrated the relationship between above metrics and the number of servers. Finally, by demonstrating the effective number of servers, it illuminate that we should deploy appropriate number of servers for a certain condition.

This document provides recommendations of best current practice for dropping or marking packets using any active queue management (AQM) algorithm, including Random Early Detection (RED), BLUE, Pre- Congestion Notification (PCN), and newer schemes such as CoDel (Controlled Delay) and PIE (Proportional Integral controller Enhanced). We give three strong recommendations: (1) packet size should be taken into account when transports detect and respond to congestion indications, (2) packet size should not be taken into account when network equipment creates congestion signals (marking, dropping), and therefore (3) in the specific case of RED, the byte- mode packet drop variant that drops fewer small packets should not be used. This memo updates RFC 2309 to deprecate deliberate preferential treatment of small packets in AQM algorithms.

As use of non-TCP applications such as streaming media and network games increases, the potential for unfair, misbehaving flows and the threat of congestion collapse also increases. This paper introduces a statistical traffic filtering technique, stochastic fairness guardian (SFG), that effectively regulates misbehaving flows with minimal traffic state information. SFG can be used in conjunction with an active queue management (AQM) mechanism to improve both network protection and efficiency. Simulations are used to evaluated SFG and the integration of SFG with a proportional-integral (PI) controller in comparison with other similar statistical flow management mechanisms including RED-PD, SFB and CHOKe. The SFG-PI combination outperforms other mechanisms in terms of fairness, queuing delay, stability and TCP performance over a wide range of realistic traffic loads and conditions.

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

The explosive increase in the volume and variety of Internet traffic has placed a growing emphasis on congestion control and fairness in Internet routers. Approaches to the problem of congestion, such as active queue management schemes like Random Early Detection (RED) use congestion avoidance techniques and are successful with TCP flows. Approaches to the problem of fairness, such as Fair Random Early Drop (FRED), keep per-flow state and punish misbehaved, non-TCP flows. Unfortunately, these punishment mechanisms also result in a significant performance drop for multimedia flows that use flow control. We extend Class-Based Threshold (CRT) [12], and propose a new active queue management mechanism as an extension to RED called Dynamic Class-Based Threshold (D- CBT) to improve multimedia performance on the Internet. Also, as an effort to reduce multimedia jitter, we propose a lightweight packet scheduling called Cut-In Packet Scheduling (ChIPS) as an alternative to FIFO packet scheduling. The performance of our proposed mechanisms is measured, analyzed and compared with other mechanisms (RED and CBT) in terms of throughput, fairness and multimedia jitter through simulation using NS. The study shows that D-CBT improves fairness among different classes of flows and ChIPS improves multimedia jitter without degrading fairness.

In recent years, Active Queue Management (AQM) mechanisms to improve the performance of TCP/IP networks have acquired a relevant role. In this paper, we present a simple and robust RED-type algorithm together with a couple of dynamical variants with the ability to adapt to the specific characteristics of different network environments, as well as to the user’s needs. We first present a basic version called Beta RED (BetaRED), where the parameters can be tuned according to the specific network conditions. The aim is to introduce control parameters that are easy to interpret and provide a good performance over a wide range of values. Secondly, BetaRED is used as a framework to design two dynamic algorithms, which we will call Adaptive Beta RED (ABetaRED) and Dynamic Beta RED (DBetaRED). In those new algorithms, certain parameters are dynamically adjusted so that the queue length remains stable around a predetermined reference value and according to changing network traffic conditions. Finally, we present a battery of simulations using the Network Simulator 3 (ns-3) software with a two-fold objective: to guide the user on how to adjust the parameters of the BetaRED mechanism, and to show a performance comparison of ABetaRED and DBetaRED with other representative algorithms that pursue a similar objective.

Random early detection (RED) is an active queue management (AQM) mechanism for routers on the Internet. In this paper, performance of RED and adaptive RED is compared from the viewpoint of nonlinear dynamics. In particular, we reveal the relationship between the performance of the network and its nonlinear dynamical behavior. We measure the maximal Lyapunov exponent and Hurst parameter of the average queue length of RED and adaptive RED, as well as the throughput and packet loss rate of the aggregate traffic on the bottleneck link. Our simulation scenarios include FTP flows and Web flows, one-way and two-way traffic. In most situations, adaptive RED has smaller maximal Lyapunov exponents, lower Hurst parameters, higher throughput and lower packet loss rate than that of RED. This confirms that adaptive RED has better performance than RED.

One of the main objectives of Active Queue Management (AQM) mechanisms is to provide low delay and low packet loss in best-effort service networks. Nevertheless, AQM algorithms exhibit some weaknes ...

In this paper we address the issue of cross-layer design in transport layer enhancement mechanisms, where the data-link and transport layer information is shared with each other, in order to provide improved system throughput of the wireless cellular network. We propose a cross-layer transport layer enhancement mechanism with name of XST (cross-layer snoop protocol for TCP), which is based on Snoop protocol combined with the forced duplicate acknowledgement congestion control strategy in wireless cellular networks. XST employs the cross-layer design, working at the data-link layer but using the transport layer information as operating criteria. We conduct a comparative study between the XST mechanism and active queue management (AQM) mechanism in the literature, such as random early detection (RED) in wireless environments with varying link characteristics. Simulation results demonstrate that the proposed XST significantly outperforms RED in wireless cellular network, especially under high-error-rate which is a major characteristic of wireless links.

This document discusses the metrics to be considered in an evaluation of new or modified congestion control mechanisms for the Internet. These include metrics for the evaluation of new transport protocols, of proposed modifications to TCP, of application-level congestion control, and of Active Queue Management (AQM) mechanisms in the router. This document is the first in a series of documents aimed at improving the models that we use in the evaluation of transport protocols. This document is a product of the Transport Modeling Research Group (TRMG), and has received detailed feedback from many members of the Research Group (RG). As the document tries to make clear, there is not necessarily a consensus within the research community (or the IETF community, the vendor community, the operations community, or any other community) about the metrics that congestion control mechanisms should be designed to optimize, in terms of tradeoffs between throughput and delay, fairness between competing flows, and the like. However, we believe that there is a clear consensus that congestion control mechanisms should be evaluated in terms of tradeoffs between a range of metrics, rather than in terms of optimizing for a single metric.