7,377 research outputs found

    Congestion control for transmission control protocol (TCP) over asynchronous transfer mode (ATM) networks

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    Performance of Transmission Control Protocol (TCP) connections in high-speed Asynchronous Transfer Model (ATM) networks is of great importance due to the widespread use of the TCP/IP protocol for data transfers and the increasing deployment of ATM networks. When TCP runs on top of ATM network, the TCP window based and ATM rate based congestion control mechanisms interact with each other. TCP performance may be degraded by the mismatch between the two mechanisms. We study the TCP performance over ATM networks with Unspecified Bit Rate (UBR) service and Available Bit Rate (ABR) service under various congestion control mechanisms by using simulation techniques, and propose a novel congestion control algorith, "Fair Intelligent Congestion Control", which significantly enhances the congestion control efficiency and improves the TCP performance over ATM networks

    Congestion Control and Traffic Management in ATM Networks: Recent Advances and A Survey

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    Congestion control mechanisms for ATM networks as selected by the ATM Forum traffic management group are described. Reasons behind these selections are explained. In particular, selection criteria for selection between rate-based and credit-based approach and the key points of the debate between the two approaches are presented. The approach that was finally selected and several other schemes that were considered are described.Comment: Invited submission to Computer Networks and ISDN System

    Explicit congestion control algorithms for available bit rate services in asynchronous transfer mode networks

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    Congestion control of available bit rate (ABR) services in asynchronous transfer mode (ATM) networks has been the recent focus of the ATM Forum. The focus of this dissertation is to study the impact of queueing disciplines on ABR service congestion control, and to develop an explicit rate control algorithm. Two queueing disciplines, namely, First-In-First-Out (FIFO) and per-VC (virtual connection) queueing, are examined. Performance in terms of fairness, throughput, cell loss rate, buffer size and network utilization are benchmarked via extensive simulations. Implementation complexity analysis and trade-offs associated with each queueing implementation are addressed. Contrary to the common belief, our investigation demonstrates that per-VC queueing, which is costlier and more complex, does not necessarily provide any significant improvement over simple FIFO queueing. A new ATM switch algorithm is proposed to complement the ABR congestion control standard. The algorithm is designed to work with the rate-based congestion control framework recently recommended by the ATM Forum for ABR services. The algorithm\u27s primary merits are fast convergence, high throughput, high link utilization, and small buffer requirements. Mathematical analysis is done to show that the algorithm converges to the max-min fair allocation rates in finite time, and the convergence time is proportional to the distinct number of fair allocations and the round-trip delays in the network. At the steady state, the algorithm operates without causing any oscillations in rates. The algorithm does not require any parameter tuning, and proves to be very robust in a large ATM network. The impact of ATM switching and ATM layer congestion control on the performance of TCP/IP traffic is studied and the results are presented. The study shows that ATM layer congestion control improves the performance of TCP/IP traffic over ATM, and implementing the proposed switch algorithm drastically reduces the required switch buffer requirements. In order to validate claims, many benchmark ATM networks are simulated, and the performance of the switch is evaluated in terms of fairness, link utilization, response time, and buffer size requirements. In terms of performance and complexity, the algorithm proposed here offers many advantages over other proposed algorithms in the literature

    Rate-Based End-to End Closed Loop Control for ABR Traffic Management

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    ATM has one common feature which guarantees its success, namely the possibility to transport any ATM service, irrespective of its characteristics such as the bit rate, its quality requirements or its bursty nature. ATM also has high flexibility in allocate the bandwidth, and thus allows more calls to enter the network. Unfortunately, this advantage has a negative consequences. ATM presents congestion problems in the network as well as in the end terminals. This research describes about congestion control mechanism that will be applied for Available Bit Rate (ABR) Service in ATM networks, namely, the Rate-Based Congestion Control Scheme. This method supports end-to-end closed-loop control and has been indentified as the most appropriate for the support of this service by ATM Forum. ABR Service is a new ATM Service category. This kind of service automatically and dynamically allocates the available bandwidth to users by controlling the traffic flow based on feedback information. The source increases or decreases the source rate of cells transmission based on the information in the feedback Resource Management (RM) cell it receives. This method minimizes the duties of intermediate nodes and the destination node, so it is expected the source will receive the feedback information faster

    Source Behavior for ATM ABR Traffic Management: An Explanation

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    The Available Bit Rate (ABR) service has been developed to support data applications over Asynchronous Transfer Mode (ATM) networks. The network continuously monitors its traffic and provides feedback to the source end systems. This paper explains the rules that the sources have to follow to achieve a fair and efficient allocation of network resources.Comment: IEEE Communications Magazine, November 1, 1996, vol 34, no11, pp50-5

    Quality of Service over Specific Link Layers: state of the art report

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    The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service
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