Tcp Ftat Fast Transmit Adaptive Transmission A New End To End Congestion Control Algorithm
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| Author | : Mohammed Ahmed Melegy Mohammed Afifi |
| Publisher | : |
| Total Pages | : 95 |
| Release | : 2014 |
| Genre | : Local area networks (Computer networks) |
| ISBN | : |
Abstract: Congestion Control in TCP is the algorithm that controls allocation of network resources for a number of competing users sharing a network. The nature of computer networks, which can be described from the TCP protocol perspective as unknown resources for unknown traffic of users, means that the functionality of the congestion control algorithm in TCP requires explicit feedback from the network on which it operates. Unfortunately this is not the way it works with TCP, as one of the fundamental principles of the TCP protocol is to be end-to-end, in order to be able to operate on any network, which can consist of hundreds of routers and hundreds of links with varying bandwidth and capacities. This fact requires the Congestion Control algorithm to be adaptive by nature, to adapt to the network environment under any given circumstances and to obtain the required feedback implicitly through observation and measurements. In this thesis we propose a new TCP end-to-end congestion control algorithm that provides performance improvements over existing TCP congestion control algorithms in computer networks in general, and an even greater improvement in wireless and/or high bandwidth- delay product networks.
| Author | : Christos N. Houmkozlis |
| Publisher | : CRC Press |
| Total Pages | : 332 |
| Release | : 2017-12-19 |
| Genre | : Computers |
| ISBN | : 143984058X |
Establishing adaptive control as an alternative framework to design and analyze Internet congestion controllers, End-to-End Adaptive Congestion Control in TCP/IP Networks employs a rigorously mathematical approach coupled with a lucid writing style to provide extensive background and introductory material on dynamic systems stability and neural network approximation; alongside future internet requests for congestion control architectures. Designed to operate under extreme heterogeneous, dynamic, and time-varying network conditions, the developed controllers must also handle network modeling structural uncertainties and uncontrolled traffic flows acting as external perturbations. The book also presents a parallel examination of specific adaptive congestion control, NNRC, using adaptive control and approximation theory, as well as extensions toward cooperation of NNRC with application QoS control. Features: Uses adaptive control techniques for congestion control in packet switching networks Employs a rigorously mathematical approach with lucid writing style Presents simulation experiments illustrating significant operational aspects of the method; including scalability, dynamic behavior, wireless networks, and fairness Applies to networked applications in the music industry, computers, image trading, and virtual groups by techniques such as peer-to-peer, file sharing, and internet telephony Contains working examples to highlight and clarify key attributes of the congestion control algorithms presented Drawing on the recent research efforts of the authors, the book offers numerous tables and figures to increase clarity and summarize the algorithms that implement various NNRC building blocks. Extensive simulations and comparison tests analyze its behavior and measure its performance through monitoring vital network quality metrics. Divided into three parts, the book offers a review of computer networks and congestion control, presents an adaptive congestion control framework as an alternative to optimization methods, and provides appendices related to dynamic systems through universal neural network approximators.
| Author | : Christo Ananth |
| Publisher | : Grin Publishing |
| Total Pages | : 68 |
| Release | : 2017-10-24 |
| Genre | : |
| ISBN | : 9783668545618 |
Project Report from the year 2017 in the subject Engineering - Computer Engineering, grade: 4.5, language: English, abstract: In this project, we describe FAST TCP, a new TCP congestion control algorithm for high-speed long-latency networks, from design to implementation. We highlight the approach taken by FAST TCP to address the four difficulties, at both packet and flow levels, which the current TCP implementation has at large windows. We describe the architecture and characterize the equilibrium and stability properties of FAST TCP. We present experimental results comparing our first Linux prototype with TCP Reno, HSTCP, and STCP in terms of throughput, fairness, stability, and responsiveness. FAST TCP aims to rapidly stabilize high-speed long-latency networks into steady, efficient and fair operating points, in dynamic sharing environments, and the preliminary results are produced as output of our project. We also explain our project with the help of an existing real-time example as to explain why we go for the TCP download rather than FTP download. The real-time example that is chosen is Torrents which we use for Bulk and safe-downloading. We finally conclude with the results of our new congestion control algorithm aided with the graphs obtained during its simulation in NS2.
| Author | : Gururaj H L |
| Publisher | : GRIN Verlag |
| Total Pages | : 138 |
| Release | : 2021-02-15 |
| Genre | : Computers |
| ISBN | : 3346345009 |
Thesis (M.A.) from the year 2019 in the subject Engineering - Computer Engineering, , language: English, abstract: The digital era of communications shapes the globe from wired networks to wireless network, offline media to online media. The mobile adhoc network is one of the major categories of network where the users depends upon and accessing the services too. As the number of users increases in accessing the data in mobile adhoc networks, the major challenging issue is congestion. The type of data transmitting and receiving in mobile adhoc networks mainly deals with multimedia data i. e audio, video and animations. The bandwidth utilization is high in case of multimedia data in the mobile ad hoc network when compared to other data payloads. The network performance level can be optimized by reducing the congestion in mobile adhoc networks. It is highly difficult to provide best performance to meet the user expectations in mobile adhoc networks. As in mobile adhoc network, Congestion control at the transport layer is the greater role. Subsequently, the various compound designs are being used and system which has to adjusted as per the service providers. As Quality of Service is very much required by users in mobile adhoc networks and it’s very much problematic to attain them by having a less number of resources. TCP is the standard protocol of transport layer which behaves in different flavors. Among such variants NewReno and HSTCP are the most commonly used. However the performance of TCP NewReno and HSTCP are very much sensitive to immediate changes in the traffic load. For achieving the QoS in mobile adhoc networks the problems related with congestion issues has to be addressed. The proposed work identifies certain number of issues during the improvement of QoS in mobile adhoc networks. Hence, the proposed algorithms MHSTCP and SwTCP are designed and developed. MHSTCP and SwTCP give attention towards few parameters such as Bandwidth utilization, Data rate, Delay, and energy. The proposed algorithms are simulated in Network Simulator-2 by varying impairments and results are verified. Based on the simulation results, the research outcome shows that the proposed algorithms outperform the existing TCP congestion control variants in enhancing the QoS parameters in Mobile adhoc networks.
| Author | : Breeson Francis |
| Publisher | : |
| Total Pages | : |
| Release | : 2012 |
| Genre | : TCP/IP (Computer network protocol) |
| ISBN | : |
Transmission Control Protocol (TCP) designed to deliver seamless and reliable end-to-end data transfer across unreliable networks works impeccably well in wired environment. In fact, TCP carries the around 90% of Internet traffic, so performance of Internet is largely based on the performance of TCP. However, end-to-end throughput in TCP degrades notably when operated in wireless networks. In wireless networks, due to high bit error rate and changing level of congestion, retransmission timeouts for packets lost in transmission is unavoidable. TCP misinterprets these random packet losses, due to the unpredictable nature of wireless environment, and the subsequent packet reordering as congestion and invokes congestion control by triggering fast retransmission and fast recovery, leading to underutilization of the network resources and affecting TCP performance critically. This thesis reviews existing approaches, details two proposed systems for better handling in networks with random loss and delay. Evaluation of the proposed systems is conducted using OPNET simulator by comparing against standard TCP variants and with varying number of hops.
| Author | : Md. Israfil Biswas |
| Publisher | : |
| Total Pages | : 366 |
| Release | : 2011 |
| Genre | : Internet governance |
| ISBN | : |
It concluded that CWV is too conservative to support many bursty applications and does not provide an incentive to encourage use by application designers. Instead, application designers often avoid generating variable-rate traffic by padding idle periods, which has been shown to waste network resources. CWV is therefore shown to not provide an acceptable solution for variable-rate traffic. In response to this shortfall, a new modification to TCP, TCP-JAGO, is proposed. This allows variable-rate traffic to restart quickly after an inactive (i.e., idle) period and to effectively utilise available network resources while sending at a lower rate than the available rate (i.e., during an application-limited period). The analysis in Chapter five shows that JAGO provides faster convergence to a steady-state rate and improves throughput by more efficiently utilising the network. TCP-JAGO is also shown to provide an appropriate response when congestion is experienced after restart. Variable-rate TCP traffic can also be impacted by the Initial Window algorithm at the start or during the restart of a session. Chapter six considers this problem, where TCP has no prior indication of the network state. A recent proposal for a larger initial window is analysed. Issues and advantages of using a large IW over a range of scenarios are discussed. The thesis concludes by presenting recommendations to improve TCP support for bursty applications. This also provides an incentive for application designers to choose TCP for variable-rate traffic.
| Author | : Soohyun Cho |
| Publisher | : |
| Total Pages | : |
| Release | : 2006 |
| Genre | : |
| ISBN | : |
In this work, we focus on congestion control mechanisms in Transmission Control Protocol (TCP) for emerging very-high bandwidth-delay product networks and suggest several congestion control schemes for parallel and single-flow TCP. Recently, several high-speed TCP proposals have been suggested to overcome the limited throughput achievable by single-flow TCP by modifying its congestion control mechanisms. In the meantime, users overcome the throughput limitations in high bandwidth-delay product networks by using multiple parallel TCP flows, without modifying TCP itself. However, the evident lack of fairness between the high-speed TCP proposals (or parallel TCP) and existing standard TCP has increasingly become an issue. In many scenarios where flows require high throughput, such as grid computing or content distribution networks, often multiple connections go to the same or nearby destinations and tend to share long portions of paths (and bottlenecks). In such cases benefits can be gained by sharing congestion information. To take advantage of this additional information, we first propose a collaborative congestion control scheme for parallel TCP flows. Although the use of parallel TCP flows is an easy and effective way for reliable high-speed data transfer, parallel TCP flows are inherently unfair with respect to single TCP flows. In this thesis we propose, implement, and evaluate a natural extension for aggregated aggressiveness control in parallel TCP flows. To improve the effectiveness of single TCP flows over high bandwidth-delay product networks without causing fairness problems, we suggest a new TCP congestion control scheme that effectively and fairly utilizes high bandwidth-delay product networks by adaptively controlling the flow's aggressiveness according to network situations using a competition detection mechanism. We argue that competition detection is more appropriate than congestion detection or bandwidth estimation. We further extend the adaptive aggressiveness control mechanism and the competition detection mechanism from single flows to parallel flows. In this way we achieve adaptive aggregated aggressiveness control. Our evaluations show that the resulting implementationis effective and fair. As a result, we show that single or parallel TCP flows in end-hosts can achieve high performance over emerging high bandwidth-delay product networks without requiring special support from networks or modifications to receivers.
| Author | : Sumitha Bhandarkar |
| Publisher | : |
| Total Pages | : |
| Release | : 2010 |
| Genre | : |
| ISBN | : |
In this dissertation we examine some of the challenges faced by the congestion control algorithms of TCP in emerging networks. We focus on three main issues. First, we propose TCP with delayed congestion response (TCP-DCR), for improving performance in the presence of non-congestion events. TCP-DCR delays the conges- tion response for a short interval of time, allowing local recovery mechanisms to handle the event, if possible. If at the end of the delay, the event persists, it is treated as congestion loss. We evaluate TCP-DCR through analysis and simulations. Results show significant performance improvements in the presence of non-congestion events with marginal impact in their absence. TCP-DCR maintains fairness with standard TCP variants that respond immediately. Second, we propose Layered TCP (LTCP), which modifies a TCP flow to behave as a collection of virtual flows (or layers), to improve eficiency in high-speed networks. The number of layers is determined by dynamic network conditions. Convergence properties and RTT-unfairness are maintained similar to that of TCP. We provide the intuition and the design for the LTCP protocol and evaluation results based on both simulations and Linux implementation. Results show that LTCP is about an order of magnitude faster than TCP in utilizing high bandwidth links while maintaining promising convergence properties. Third, we study the feasibility of employing congestion avoidance algorithms in TCP. We show that end-host based congestion prediction is more accurate than previously characterized. However, uncertainties in congestion prediction may be un- avoidable. To address these uncertainties, we propose an end-host based mechanism called Probabilistic Early Response TCP (PERT). PERT emulates the probabilistic response function of the router-based scheme RED/ECN in the congestion response function of the end-host. We show through extensive simulations that, similar to router-based RED/ECN, PERT provides fair bandwidth sharing with low queuing delays and negligible packet losses, without requiring the router support. It exhibits better characteristics than TCP-Vegas, the illustrative end-host scheme. PERT can also be used for emulating other router schemes. We illustrate this through prelim- inary results for emulating the router-based mechanism REM/ECN. Finally, we show the interactions and benefits of combining the different proposed mechanisms.
| Author | : M. A. Alnuem |
| Publisher | : |
| Total Pages | : |
| Release | : 2009 |
| Genre | : |
| ISBN | : |
Transmission Control Protocol (TCP) is considered one of the most important protocolsin the Internet. An important mechanism in TCP is the congestion controlmechanism which controls TCP sending rate and makes TCP react to congestionsignals. Nowadays in heterogeneous networks, TCP may work in networks with somelinks that have lossy nature (wireless networks for example). TCP treats all packetloss as if they were due to congestion. Consequently, when used in networks thathave lossy links, TCP reduces sending rate aggressively when there are transmission(non-congestion) errors in an uncongested network. One solution to the problem is to discriminate between errors; to deal with congestionerrors by reducing TCP sending rate and use other actions for transmissionerrors. In this work we investigate the problem and propose a solution using anend-to-end error discriminator. The error discriminator will improve the currentcongestion window mechanism in TCP and decide when to cut and how much tocut the congestion window. We have identified three areas where TCP interacts with drops: congestion windowupdate mechanism, retransmission mechanism and timeout mechanism. All ofthese mechanisms are part of the TCP congestion control mechanism. We proposechanges to each of these mechanisms in order to allow TCP to cope with transmissionerrors. We propose a new TCP congestion window action (CWA) for transmissionerrors by delaying the window cut decision until TCP receives all duplicate acknowledgmentsfor a given window of data (packets in flight). This will give TCP a clearimage about the number of drops from this window. The congestion window size isthen reduced only by number of dropped packets. Also, we propose a safety mechanismto prevent this algorithm from causing congestion to the network by usingan extra congestion window threshold (tthresh) in order to save the safe area wherethere are no drops of any kind. The second algorithm is a new retransmission actionto deal with multiple drops from the same window. This multiple drops action(MDA) will prevent TCP from falling into consecutive timeout events by resendingall dropped packets from the same window. A third algorithm is used to calculatea new back-off policy for TCP retransmission timeout based on the network?s availablebandwidth. This new retransmission timeout action (RTA) helps relating thelength of the timeout event with current network conditions, especially with heavytransmission error rates. The three algorithms have been combined and incorporated into a delay basederror discriminator. The improvement of the new algorithm is measured along withthe impact on the network in terms of congestion drop rate, end-to-end delay, averagequeue size and fairness of sharing the bottleneck bandwidth. The results show thatthe proposed error discriminator along with the new actions toward transmissionerrors has increased the performance of TCP. At the same time it has reduced theload on the network compared to existing error discriminators. Also, the proposederror discriminator has managed to deliver excellent fairness values for sharing thebottleneck bandwidth. Finally improvements to the basic error discriminator have been proposed byusing the multiple drops action (MDA) for both transmission and congestion errors. The results showed improvements in the performance as well as decreases in thecongestion loss rates when compared to a similar error discriminator.
| Author | : Lianjie Cao |
| Publisher | : |
| Total Pages | : 136 |
| Release | : 2011 |
| Genre | : Computer algorithms |
| ISBN | : |
Traditional TCP/IP networks provide a best effort delivery service which places the complexity of congestion control in the end hosts, leaving the network relatively simple. It is well-known that the performance of the TCP congestion control scheme degrades severely under conditions of large bandwidth-delay products and/or high loss rates. As the traffic load on the Internet increases, overall network performance and the quality-of-service (QoS) experienced by individual users will degrade. To address this problem, a rate-based congestion control system operating as an overlay network is studied. The nodes in the overlay network provide congestion control for the overlay links, which correspond to physical network paths. By implementing congestion control as an overlay, network congestion can be alleviated without significantly increasing the complexity of the network. In this thesis, a bandwidth probe control (BPC) system is designed for an overlay link, which estimates the delay and loss characteristics of the overlay link by probing and then uses this information dynamically to determine an appropriate transmission rate for the link. A rate control algorithm is proposed for this purpose, based on a simplified fuzzy logic controller. In contrast, the legacy TCP/IP congestion control is based on an additive-increase, multiplicative-decrease (AIMD) control scheme triggered by packet loss timeouts. The proposed rate control scheme can achieve much higher utilization and more stable performance than TCP/IP congestion control, which is especially crucial for the rate-based congestion control overlay. The BPC system also provides reasonable fairness to cross-traffic which may traverse a portion of the overlay link, thus sharing the link capacity. The BPC system was originally developed as an overlay version of the Software Adaptive Flow-Intelligent RoutEr (SAFIRE) which was developed as part of the Control for High-throughput Adaptive Resilient Transport (CHART) project, led by Hewlett-Packard (HP) Laboratories and sponsored by the DARPA Internet Control Plane program.
