Throughput and fairness of multiple TCP connections in wireless networks

TCP suffers from poor throughput performance in wireless networks. Furthermore, when multiple TCP connections compete at the base station, link errors and congestion lead to serious unfairness among the connections. Although the issue of TCP performance in wireless networks has attracted significant attention, most reports focus only on TCP throughput and assume that there is only a single connection in a congestion-free network. This paper studies the throughput and fairness of popular improvement mechanisms (the Snoop [8] and ELN [5]) and TCP variants with multiple TCP connections. Simulation results show that the improvement mechanisms under investigation are effective to improve TCP throughput in a wireless network. However, they cannot provide fairness among multiple TCP connections. From the studies presented, it is concluded that mechanisms to enhance TCP fairness are needed in wireless network

TCP Congestion Control Identification

Transmission Control Protocol (TCP) carries most of the traffic on the Internet these days. There are several implementations of TCP, and the most important difference among them is their mechanism for controlling congestion. One of the methods for determining type of a TCP is active probing. Active probing considers a TCP implementation as a black box, sends different streams of data to the appropriate host. According to the response received from the host, it figures out the type of TCP version implemented. TCP Behavior Inference Tool (TBIT) is an implemented tool that uses active probing to check the running TCP on web servers. It can check several aspects of the running TCP including initial value of congestion window, congestion control algorithm, conformant congestion control, response to selective acknowledgment, response to Explicit Congestion Notification (ECN) and time wait duration. In this paper we focus on congestion control algorithm aspect of it, explain the mechanism used by TBIT and present the results

Experiences In The Development Of A Computer Networking Course

Comunicació presentada a EDULEARN2019, 11th International Conference on Education and New Learning Technologies (July 1-3, 2019, Palma, Mallorca, Spain).The degree in Computational Mathematics Universitat Jaume I (UJI) of Castellón, Spain, is a degree that offers a training that unites mathematics with computer science and focuses on areas where both are very relevant. The graduate in this degree have a mixed profile because it combines a theoretical training, typical of a pure degree in mathematics, with the technical training of a pure degree in computer science. This mixed profile make them very versatile, that is, with the ability to perform different types of tasks and have a high rate of employment. On the other hand, their capacity for analysis and abstraction will allow them to adapt very easily to any change and innovation. This degree is composed by different courses. One of these courses is the introduction to computer networking course. Computer networks allow its users to communicate and share information regardless of the geographic distance between them. Ensuring the optimal operation of computer networks is no easy task, and there is a necessity of highly trained professionals with a solid knowledge of network planning, design, and configuration, as well as the capacity to address the different and complex connectivity and security requirements. The computer networking course provides students with the fundamental concepts of computer networks along with training to acquire the basic skills necessary to solve the various technical problems of the world of computer networks. The aim of this paper is to show the methodology and learning solutions used to train the students to to plan flexible, scalable computer networking systems for a business or organization of virtually any size. Paper shows the course objectives, the target competencies, the course contents, the assessments, and how the technology resources for e-learning are used to teach the subject

Исследование взаимодействия потоков данных в гетерогенных сетях

Проведено исследование влияния протоколов ТСР Vegas и TCP Reno на равномерность распределения доступной соединению пропускной способности. При гетерогенном управлении наблюдаются колебания размеров плавающих окон соединений различными протоколами. Предложена модификация алгоритма управления текущим окном протокола ТСР Vegas. Приведены результаты имитационного моделирования гетерогенного управления процессом передачи данных в сети. Проведен анализ результирующего трафика передачи данных в результате которого установлено, что этот трафик характеризуется параметром Херста H=0,75, что свидетельствует о его фрактальном характере

Comparative Study on the Performance of Different TCP Flavors

Indeed the Transmission Control Protocol (TCP) is the main transport layer protocol for the end-to-end control that helps the creation of information communication. Most of today`s Internet applications depend on the Performance TCP simply because the most frequently used networks by today are the TCP/IP networks. TCP was originally created to handle the problem of network congestion collapse. In this research project, we had investigated the performance of four TCP variants namely Reno, Vegas, NewReno and SACK based on two performance measures: The Bandwidth (effective throughput) and fairness. The network topology is simple wired network and it will be configured into different scenarios to maximize the chances of achieving the desired goal. Simulation methodology is used in this study. The simulation tool or software that was used as an investigation environment is the popular NS-2 simulator. The objective was to investigate and find out the performance of TCP variants according to the bandwidth and fairness in a simple dumbbell wired network, in a hope to observe a better performance.However, the results are daunting, TCP Reno is the most aggressive (least fair one), and highest amount of throughput. In the case of TCP NewReno it follows Reno’s steps by becoming the second most aggressive (second least fair), and second highest throughput.SACK (Sack1) is fair to Reno and NewReno, but when it is competing with Vegas, it shows that it is very unfair. Finally Vegas shows the highest degree of fairness (least aggressive) and as well Vegas produces the lowest amount throughput

Performance Analysis of TCP Tahoe, Reno, New Reno, Sack and Vegas using NS-2

The Transmission Control Protocol TCP is the dominating end-to-end protocol on the internet today but still it faces congestion problems in some cases To overcome congestion problems several congestion control and avoiding mechanisms namely Tahoe Reno Vegas and Sack etc all with different features and advantages but with maximal throughput as main objective which are termed as the clones of TCP have been incorporated into TCP IP protocol for handling congestion efficiently in different network scenarios However one clone cannot be suitable for each case So this paper has investigated the characteristics of the mentioned clones and calculated throughputs of them in simulated environment varying various performances metrics such as delay buffer size error rate number of traffic and bandwidth for finding which one is the best for what scenario The performance of these clones for varying network conditions and settings can effectively be evaluated using NS-2 In this work by doing simulation in NS-2 environment the throughputs of some exiting TCP implementations are calculated considering various metrics and then the calculated throughputs are compared among one another These comparisons show that which one is suitable in which case

Rate-Based End-to-End Congestion Control of Multimedia Traffic in Packet Switched Networks

This paper proposes an explicit rate-based end-to-end congestion control mechanism to alleviate congestion of multimedia traffic in packet switched networks such as the Internet. The congestion is controlled by adjusting the transmission rates of the sources in response to the feedback information from destination such as the buffer occupancy, packet arrival rate and service rate at the outgoing link, so that a desired quality of service (QoS) can be met. The QoS is defined in terms of packet loss ratio, transmission delay, power, and network utilization. Comparison studies demonstrate the effectiveness of the proposed scheme over New-Reno TCP (a variant of AIMD: additive increase multiplicative decrease) technique during simulated congestion. Since it is end-to-end, no router support is necessary, the proposed methodology can be readily applied to today\u27s Internet, as well as for real-time video and voice data transfer in unicast networks

Analisis Performansi Transmission Control Protocol (TCP) Yang Disebabkan Oleh Wideband Effect Loss Pada Jaringan UMTS

Universal Mobile Telecommunications System (UMTS) is the forthcoming global mobile network for packet data. This network uses the Wideband Code Division MultIPle Access (WCDMA) air interface. Contrary to other Radio Networks like GPRS, most of UMTS applications will be end-to-end applications and as a result the Transmission Control Protocol (TCP) will be used. In a wireless environment that used radio channel, mobile users can make the performance of system decrease. The influence of multIPath (Rayleigh fading) was calculated by MatLab software. The result from MatLab trace used in NS-2 environment to looking for the performance of UMTS system that used HSDSCH channel. The result of simulation have done, the performance of UMTS system HSDSCH channel that influence with radius user from node B, the number of user in cell, the moving of users, shadowing, multIPath, and Rayleigh fading. The best performance result was received if the radius of users is near from node B (±300m), moreless if radius users from node B is far, so the performance will be decrease