Myths about congestion management in high speed networks

European Journal of Control, 2001

The problem of controlling congestion in high-speed communication networks is introduced. An easy-toimplement explicit rate congestion control algorithm is presented, and its stability properties are discussed. The algorithm is decentralized and is robust to network delays. Furthermore, it does not require per-flow information. It is shown that the network level implementation of this algorithm leads to a``hybrid'' control system, whose analysis for stability presents challenges in a control context. A variant of the same algorithm is used in the paper to demonstrate the possibility of an Internet implementation using``marking'' with the proper choice of a rate update function.

Due to the recent trends in Internet, for exchange of information in the form of pure data traffic and multimedia traffic, High-speed network is necessary. As there is a growing demand for high-speed networks, data transfer must take place without any congestion. In data networking and queueing theory, Network congestion occurs when a link or node is carrying so much data that its quality of service deteriorates. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of these latter two is that incremental increases in offered load lead either only to small increase in network throughput, or to an actual reduction in network throughput. The Transmission Control Protocol (TCP) is one of the core protocols of the Internet Protocol Suite. TCP has not performed well on high-speed network because the standard TCP's algorithm for congestion control may cause thousands of packet drops in one Round Trip Time (RTT) and the window size is halved at the time of congestion. So the utilization of the bandwidth and throughput is minimized. The researchers developed different TCP variants to improve the performance of the congestion control algorithms in high-speed network. In this paper we propose a sequence of algorithms based on window adjustment, feedback mechanism and buffer management to overcome the limitations for high-speed network. The congestion control mechanism that we adopt starts with Queue Management, which enables to modify and control the transmission queue. The Window Adjustment Mechanism alters the Congestion window size based on the Input load. The Feedback mechanism renders the optimum load that can be serviced currently when congestion had taken place. Also the feedback information is notified to the sender. This solution to control the congestion in the network achieves maximum throughput and bandwidth utilization, with minimum delay and drop probability. The performance of the congestion window, throughput, utilization of the bandwidth, delay are analyzed and presented.

IJCSNS, 2008

In this paper an effort has been made to study various Congestion control techniques used for reducing/easing the level of congestion and subsequently avoiding the congestion of the wired communication networks in general and High Speed Networks in particular. Many authors have suggested several congestion control techniques [2], [3], [4], [8], [12], [14], [15], [23], [29], [32] & [33] and studied their behavior under various network conditions, for a range of parameters also under heterogeneous networking environments. A special effort has been made to study the problems associated with the TCP congestion control mechanisms and the several solutions that have been proposed to improve its performance. This analysis tries to study the limitations of the suggested solutions, based on various parameters and propose algorithms to overcome these limitations for the High Speed Networks.

Proc. 44th Annual Allerton …, 2006

Congestion is intrinsic to the operation of networks and is usually handled by a combination of algorithms at the link and network/transport layers. Link level algorithms alleviate "transient congestion" caused by the temporary oversubscription of a link due to a burst of packets arriving at a switch or router buffer. Network or transport level algorithms alleviate "sustained congestion" which occurs when the longterm arrival rate at a link exceeds its capacity. Algorithms at the two levels interact to provide a scalable, stable and fair bandwidth allocation to the flows passing through the network. Link level algorithms are typically very simple: drop or mark packets with increasing probability as buffer congestion increases; moreover, if a packet arrives at a full buffer, drop it. These dropped or marked packets are used by the transport algorithms to adjust the transmission rate of sources. In this paper we are concerned with networks in which packets cannot be dropped when there is congestion. In such networks a back-pressure mechanism "pauses" the link or links feeding a congested buffer, thus preventing further packets from arriving at the buffer. The links are later unpaused when the buffer becomes uncongested. This paper is a theoretical study of the stability and fairness properties of network level congestion control when pause mechanisms operate at the link level to prevent packet drops. Our focus is on the Backward Congestion Notification (BCN) algorithm which is being considered by the IEEE 802.1 standards body for deployment in switched Ethernet networks. 1 At the time of this writing the complete BCN specification was not yet available because the IEEE 802.1au Work Group was still working on the mechanism. A number of documents produced by the .1au WG can be found at [10].

Network, IEEE, 1990

Popular myths that cheaper memory, high-speed links, and high-speed processors will solve the problem of congestion in computer networks are shown to be false. A simple definition for congestion based on supply and demand of resources is proposed and is then used to classify various congestion schemes. The issues that make the congestion problem a difficult one are discussed, and the architectural decisions that affect the design of a congestion scheme are presented. It is argued that long-, medium-, and short-term congestion problems require different solutions. Some of the recent schemes are briefly surveyed, and areas for further research are suggested.

1990

The Internet has always done a remarkable job at surprising people. Technology oscillates, and some envisioned architectures of the future fail while others thrive. From the origination of peer-to-peer computing, it became easier task for communication and information transfer. But there exists still few hysterical issues like congestion, and security. Congestion occurs when one part of subnet becomes overloaded. The means of moderating the traffic in the networks is referred as congestion control. This paper critically analyses various issues behind congestion in various networks and various techniques to avoid and prevent from congestion and to efficiently control the congestion in the networks. This paper essentially focuses on the future networks posing various challenges and exposed issues regarding congestion control.

Psi Chi Journal of Psychological Research, 2020

With extensive research having illustrated the lack of self-esteem nourishing attributes that individuals with communication apprehension exhibit, the present investigation evaluated the strength of correlations between general and context-specific forms of communication apprehension and self-esteem. College students (N = 40; Mage = 19.48) completed measures that assessed their general and context-specific communication apprehension as well as their self-esteem. General and context-specific forms of communication apprehension were all predicted to be strongly and negatively correlated with self-esteem, and the correlation between interpersonal communication apprehension and self-esteem was predicted to be the strongest out of all contexts of communication apprehension. A linear regression showed a significant relation between general communication apprehension and self-esteem (R = .61, Radj = .36, p < .001). Multicollinearity in the multiple regression prevented the intended test...

Temos grande prazer em apresentar aos estudantes e investigadores da Doutrina Secreta esta pequena obra baseada nos Preceitos herméticos do mundo antigo. Existem poucos escritos sobre este assunto apesar das inúmeras referências feitas pelos ocultistas aos Preceitos que expomos, de modo que por isso esperamos que os investigadores dos Arcanos da Verdade saberão dar bom acolhimento ao livro que agora aparece. O fim desta obra não é a enunciação de uma filosofia ou doutrina especial, mas sim fornecer aos estudantes uma exposição da Verdade que servirá para reconciliar os fragmentos do conhecimento oculto que adquiriram, mas que são aparentemente opostos uns aos outros e que só servem para desanimar é desgostar o principiante neste estudo. O nosso intento não é construir um novo Templo de Conhecimento, mas sim colocar nas mãos do estudante uma Chave−Mestra com que possa abrir todas as portas internas que conduzem ao Templo do Mistério cujos portais já entrou. Nenhum fragmento dos conhecimentos ocultos possuídos pelo mundo foi tão zelosamente guardado como os fragmentos dos Preceitos herméticos que chegaram − até nós através dos séculos passados desde o tempo do seu grande estabelecedor, Hermes Trismegisto, o mensageiro dos deuses, que viveu no antigo Egito quando a atual raça humana estava em sua infância. Contemporâneo de Abraão e se for verdadeira a lenda, instrutor deste venerável sábio, Hermes foi e é o Grande Sol Central do Ocultismo, cujos raios têm iluminado todos os ensinamentos que foram publicados desde o seu tempo. Todos os preceitos fundamentais e básicos introduzidos nos ensinos esotéricos de cada raça foram formulados por Hermes. Mesmo os mais antigos preceitos da índia tiveram indubítavelmente a sua fonte nos Preceitos herméticos originais.

Hermès, 1991

PAROLE MAGIQUE ET MODERNITÉ « Toute annonce de l'avenir est une infraction à la règle et a ce danger qu'elle peut changer l'événement, auquel cas toute la science tombe par terre comme un véritable jeu d'enfant; et d'ailleurs il y avait des choses dures à dire à cette duchesse toujours si jolie. » Stendhal Une conception naïve de la communication entre les hommes consiste à ne voir en celle-ci qu'un pur et simple processus d'échange d'informations objectives entre des agents émetteurs et récepteurs, le seul problème d'importance étant dès lors celui de la compréhension du message transmis. Mais le langage a bien d'autres usages, comme l'a montré entres autres Austin (1970). En particulier, l'information communiquée peut induire des comportements qui sont tels que les agents en viennent à transformer en réalité l'événement décrit par l'information en question, alors même que cette information est transmise à l'indicatif et non comme un ordre ou un souhait, et que l'on peut raisonnablement supposer qu'en l'absence de cette anticipation, l'événement ne se serait pas produit : une anticipation de e est une condition nécessaire de l'occurrence de è.