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

Network level performance of differentiated services (diffserv) networks

The Differentiated Services (DiffServ) architecture is a promising means of providing Quality of Service (QoS) in Internet. In DiffServ networks, three service classes, or Per-hop Behaviors (PHBs), have been defined: Expedited Forwarding (EF), Assured Forwarding (AF) and Best Effort (BE). In this dissertation, the performance of DiffServ networks at the network level, such as end-to-end QoS, network stability, and fairness of bandwidth allocation over the entire network have been extensively investigated. It has been shown in literature that the end-to-end delay of EF traffic can go to infinity even in an over-provisioned network. In this dissertation, a simple scalable aggregate scheduling scheme, called Youngest Serve First (YSF) algorithm is proposed. YSF is not only able to guarantee finite end-to-end delay, but also to keep a low scheduling complexity. With respect to the Best Effort traffic, Random Exponential Marking (REM), an existing AQM scheme is studied under a new continuous time model, and its local stable condition is presented. Next, a novel virtual queue and rate based AQM scheme (VQR) is proposed, and its local stability condition has been presented. Then, a new AQM framework, Edge-based AQM (EAQM) is proposed. EAQM is easier to implement, and it achieves similar or better performance than traditional AQM schemes. With respect to the Assured Forwarding, a network-assist packet marking (NPM) scheme has been proposed. It has been demonstrated that NPM can fairly distribute bandwidth among AF aggregates based on their Committed Information Rates (CIRs) in both single and multiple bottleneck link networks

Implementation and performance analysis of a QoS-aware TFRC mechanism

This paper deals with the improvement of transport protocol behaviour over the DiffServ Assured Forwarding (AF)class. The Assured Service (AS) provides a minimum throughput guarantee that classical congestion control mechanisms, like window-based in TCP or equation-based in TCP-Friendly Rate Control (TFRC), are not able to use efficiently. In response, this paper proposes a performance analysis of a QoS aware congestion control mechanism, named gTFRC, which improves the delivery of continuous streams. The gTFRC (guaranteed TFRC) mechanism has been integrated into an Enhanced Transport Protocol (ETP) that allows protocol mechanisms to be dynamically managed and controlled. After comparing a ns-2 simulation and our implementation of the basic TFRC mechanism, we show that ETP/gTFRC extension is able to reach a minimum throughput guarantee whatever the flow’s RTT and target rate (TR) and the network provisioning conditions

Design and evaluation of an adaptive traffic conditioner in differentiated services networks

Abstract—We design and evaluate an adaptive traffic conditioner to improve application performance over the differentiated services assured forwarding behavior. The conditioner is adaptive because the marking algorithm changes based upon the current number of flows traversing through an edge router. If there are a small number of flows, the conditioner maintains and uses state information to intelligently protect critical TCP packets. On the other hand, if there are many flows going through the edge router, the conditioner only uses flow characteristics as indicated in the TCP packet headers to mark without requiring per flow state. Simulation results indicate that this adaptive conditioner improves throughput of data extensive applications like large FTP transfers, and achieves low packet delays and response times for Telnet and WWW traffic. I

Pre-Congestion Notification (PCN) Architecture

This document describes a general architecture for flow admission and termination based on pre-congestion information in order to protect the quality of service of established, inelastic flows within a single Diffserv domain.\u

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

An adaptive algorithm for Internet multimedia delivery in a DiffServ environment.

To meet the Quality of Service (QoS) requirements of multimedia applications and to reduce the network congestion, several service models and mechanisms have been proposed. Among these, Differentiated Service (DiffServ) architecture has been considered as a scalable and flexible QoS architecture for the Internet. DiffServ provides class-based QoS guarantees. Applications in different classes receive different QoS and are priced differently. If network congestion occurs, DiffServ may not be able to guarantee the QoS for the application. Thus, the QoS may not reflect the price paid for the service. A problem of considerable economic and research importance is how to achieve a good price and quality tradeoff even at times of congestion. This thesis presents an Adaptive Class Switching Algorithm (ACSA) which intends to provide good quality with good price for real-time multimedia applications in a DiffServ environment. The ACSA algorithm combines the techniques of Real-time Transport Protocol (RTP), DiffServ, and Adaptation together. It also takes both QoS and price into account to provide users a good QoS with a good price. The algorithm dynamically selects the most suitable class based on both the QoS feedback received and the highest user utility. The user utility is a function of quality, price, and the weight which reflects the relative sensitivity to quality and price. The class with the highest user utility is the class that provides the best quality and price tradeoff. The QoS feedback is conveyed by RTP\u27s Control Protocol (RTCP) Receiver Reports. The results of simulation demonstrate that ACSA can react fast to the current class state in the network and reflects the best QoS and price tradeoff. It always seeks to find a class which provides the highest user utility except when the Internet is congested and the required QoS in all classes can not be satisfied. If this happens, the real-time multimedia flow chooses Best-Effort class with no payment. (Abstract shortened by UMI.) Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .F46. Source: Masters Abstracts International, Volume: 44-01, page: 0389. Thesis (M.Sc.)--University of Windsor (Canada), 2005