Performance Evaluation of Aggregate Flow Control on Differentiated Services Syatem

Abstrak Differentiated Services (Diffserv) menyediakan cara yang sederhana untuk menangani Quality of Service (Qos) di dalam jaringan Internet Protocol (IP) dengan mekanisme klasifikasi paket dan pembedaan perlakuan, serta alokasi sumber daya jaringan untuk trafik-trafik tertentu. Masalah yang sering terjadi di Diffserv adalah unfairness dan kongesti. Untuk mengatasi masalah tersebut, maka diperlukan suatu mekanisme yang dapat mengatur aliran paket data, salah satunya adalah Aggregate Flow Control (AFC). Penggunaan AFC pada sistem tidak hanya mengendalikan kongesti, tetapi juga meningkatkan fairness dalam throughput sehingga dalam penelitian ini, kinerja Diffserv tanpa dan dengan AFC, yaitu troughput dan packet loss dievaluasi menggunakan Network Simulator 2 (NS-2). Skenario simulasi yang digunakan dalam penelitian adalah simulasi variasi jumlah microflows, variasi ukuran paket, variasi RTT, dan variasi kelas AF. Hasil simulasi menunjukkan bahwa Diffserv dengan AFC dapat meningkatkan fairness dalam throughput dan menekan packet loss yang terjadi di dalam jaringan. Namun, untuk simulasi variasi kelas AF, Diffserv dengan AFC tidak dapat menciptakan fairness dalam throughput tetapi dapat menekan packet loss yang terjadi di dalam jaringan. Kata kunci: aggregate flow control, differentiated service, fairness, network simulator, quality of service, AF PHB.  Abstract Differentiated Services (Diffserv) provides a simple way for addressing Quality of Service (QoS) in the network Internet Protocol (IP) with the packet classification mechanism and treatment differentiation as well as network resources allocation for certain traffics. A problem frequently occurs in Diffserv is unfairness and congestion. To overcome these problems, a mechanism is required to regulate the flow of data packets, one of which is Aggregate Flow Control (AFC). The use of AFC in the system does not only control congestion but also improve the fairness in throughput. This study therefore evaluates the performance of Diffserv with and without AFC, namely  throughput and packet loss, using the Network Simulator 2 (NS-2). Simulation scenario used in this study were simulations of varied microflows amount, packet size, RTT, and AF class. Simulation result showed that Diffserv with AFC could increase fairness in throughput and decrease packet loss in network. In the case of AF class variation, Diffserv with AFC could not increase fairness in throughput but decrease the packet loss that happened in the network. Keywords:     aggregate flow control, differentiated service, fairness, network simulator, quality of service, AF PHB.Â

GTFRC, a TCP friendly QoS-aware rate control for diffserv assured service

This study addresses the end-to-end congestion control support over the DiffServ Assured Forwarding (AF) class. The resulting Assured Service (AS) provides a minimum level of throughput guarantee. In this context, this article describes a new end-to-end mechanism for continuous transfer based on TCP-Friendly Rate Control (TFRC). The proposed approach modifies TFRC to take into account the QoS negotiated. This mechanism, named gTFRC, is able to reach the minimum throughput guarantee whatever the flow’s RTT and target rate. Simulation measurements and implementation over a real QoS testbed demonstrate the efficiency of this mechanism either in over-provisioned or exactly-provisioned network. In addition, we show that the gTFRC mechanism can be used in the same DiffServ/AF class with TCP or TFRC flows

gTFRC: a QoS-aware congestion control algorithm

This study addresses the end-to-end congestion control support over the DiffServ Assured Forwarding (AF) class. The resulting Assured Service (AS) provides a minimum level of throughput guarantee. In this context, this paper describes a new end-to-end mechanism for continuous transfer based on TCP-Friendly Rate Control (TFRC) originally proposed in [11]. The proposed approach modifies TFRC to take into account the QoS negotiated. This mechanism, named gTFRC, is able to reach the minimum throughput guarantee whatever the flow's RTT and target rate. Simulation measurements show the efficiency of this mechanism either in over-provisioned or exactly-provisioned network. In addition, we show that the gTFRC mechanism can be used in the same DiffServ/AF class with TCP or TFRC flows

TCP throughput guarantee in the DiffServ Assured Forwarding service: what about the results?

Since the proposition of Quality of Service architectures by the IETF, the interaction between TCP and the QoS services has been intensively studied. This paper proposes to look forward to the results obtained in terms of TCP throughput guarantee in the DiffServ Assured Forwarding (DiffServ/AF) service and to present an overview of the different proposals to solve the problem. It has been demonstrated that the standardized IETF DiffServ conditioners such as the token bucket color marker and the time sliding window color maker were not good TCP traffic descriptors. Starting with this point, several propositions have been made and most of them presents new marking schemes in order to replace or improve the traditional token bucket color marker. The main problem is that TCP congestion control is not designed to work with the AF service. Indeed, both mechanisms are antagonists. TCP has the property to share in a fair manner the bottleneck bandwidth between flows while DiffServ network provides a level of service controllable and predictable. In this paper, we build a classification of all the propositions made during these last years and compare them. As a result, we will see that these conditioning schemes can be separated in three sets of action level and that the conditioning at the network edge level is the most accepted one. We conclude that the problem is still unsolved and that TCP, conditioned or not conditioned, remains inappropriate to the DiffServ/AF service

A Utility-based QoS Model for Emerging Multimedia Applications

Existing network QoS models do not sufficiently reflect the challenges faced by high-throughput, always-on, inelastic multimedia applications. In this paper, a utility-based QoS model is proposed as a user layer extension to existing communication QoS models to better assess the requirements of multimedia applications and manage the QoS provisioning of multimedia flows. Network impairment utility functions are derived from user experiments and combined to application utility functions to evaluate the application quality. Simulation is used to demonstrate the validity of the proposed QoS model

Design, implementation and evaluation of a QoS-aware transport protocol

In the context of a reconfigurable transport protocol framework, we propose a QoS-aware Transport Protocol (QSTP), specifically designed to operate over QoS-enabled networks with bandwidth guarantee. QSTP combines QoS-aware TFRC congestion control mechanism, which takes into account the network-level bandwidth reservations, with a Selective ACKnowledgment (SACK) mechanism in order to provide a QoS-aware transport service that fill the gap between QoS enabled network services and QoS constraint applications. We have developed a prototype of this protocol in the user-space and conducted a large range of measurements to evaluate this proposal under various network conditions. Our results show that QSTP allows applications to reach their negotiated QoS over bandwidth guaranteed networks, such as DiffServ/AF network, where TCP fails. This protocol appears to be the first reliable protocol especially designed for QoS network architectures with bandwidth guarantee

Final report on the evaluation of RRM/CRRM algorithms

Deliverable public del projecte EVERESTThis deliverable provides a definition and a complete evaluation of the RRM/CRRM algorithms selected in D11 and D15, and evolved and refined on an iterative process. The evaluation will be carried out by means of simulations using the simulators provided at D07, and D14.Preprin