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2008
This paper investigates the degradation of to mice flows caused by standard TCP congestion control mechanisms, especially during the Slow Start phase what can cause multiple packet losses. Thus, a modified TCP startup mechanism was proposed. The Burst TCP (B-TCP) is an intuitive TCP startup mechanism that employs a responsive window growth scheme to improve performance of small flows. Moreover, B-TCP is easy to implement and requires TCP adjustment at the sender side only. Simulation experiments show that B-TCP can significantly reduce transfer times and packet losses of small flows without causing damage to large flows.
2007
Standard TCP congestion control mechanisms degrade performance of small flows, especially during the Slow Start phase, which often causes multiple packet losses. We propose a modified TCP startup mechanism, called Burst TCP (B-TCP), which employs a responsive growth scheme based on current window size, to improve performance for small flows. Our simulation experiments, considering heavy-tailed traffic, show that B-TCP can significantly reduce both transfer times and packet losses for small flows without causing damage to large flows. Additionally, B-TCP is easy to implement and requires TCP adjustment at the sender side only.
A reliable end to end communication is a buzzword that is promised by the transport layer protocol TCP. TCP, a Reliable transport protocols are tuned to perform well in different networks but, packet losses occur mostly because of congestion. TCP contains several mechanisms (such as slow start, congestion avoidance, fast retransmit and fast recovery) for ensuring reliability. However, it has reached its limitation in some challenging network environments like-High speed communication, Communication over different media. Thus, it requires further analysis and development of congestion control algorithms. In this paper, we have explored the reliability and robustness of TCP variants (Tahoe, Reno, New-Reno, SACK, FACK and TCP VEGAS, HSTCP, CUBIC TCP) based on different parameters such as throughput, end-to-delay, jitter and packet drop ratio over wired and wireless networks. We have also compared and discussed different congestion control and avoidance mechanisms of TCP variants to show how they affect the throughput and efficiency of different network environments.
2009 First International Conference on Evolving Internet, 2009
In this document, we introduce Cap Start TCP, an adaptive Slow Start scheme that consistently achieves fast TCP file transfer times regardless of high speed network scenario. Once the TCP session is established, we estimate TCP session path capacity scenario, and tune the transport protocol to deliver fast transfer times. We demonstrate significant transaction performance improvements, of as much as three times faster completion times in transcontinental high speed network experiments for various capacity scenarios.
2003
Short web transfers that dominate the Internet suffer from TCP's inadequate provisioning for short flows. This paper surveys ten proposals that attempt to solve one or more of the problems of short flows, and suggests general criteria to evaluate them. The proposals range from T/TCP in 1992 to RIO-PS in 2001. We classify the proposals into three categories: (1) those that reduce connection setup/teardown overheads, (2) those that use different network state sharing mechanisms, and (3) those that improve performance during slow start.
— The Transmission Control Protocol (TCP), a key functional building block of the Internet, operates as a rate-adaptive end-to-end protocol at the Transport Layer of the network protocol stack. It regulates the prevailing load conditions within the network by getting the source node to adapt the packet transfer rate in accord with the processing capacity of the receiver. The regulation is enforced by means of dropping of packets on the part of the receiver. The TCP sender then reduces the packet injection rate so as to allow the network to recover from congestion. The focus of this paper is performance evaluation of certain notable TCP congestion avoidance algorithms, namely, Vegas, Reno and New Reno. Specifically, a number of performance measures have been analysed based on ns-2 simulation data where the scenarios involved TCP flows operating with identical and cross-variant congestion control mechanisms. Congestion window behaviour, packet loss, throughput, transmission delay and jitter are the performance criteria studied with the setup mentioned. In the flows with identical variants, Vegas outperforms other TCP variants. However, TCP Vegas has been observed to contribute to unfair appropriation of the resources in the cross-variant setting. I. INTRODUCTION Transmission Control Protocol is a widely used connection-oriented transport layer protocol which provides a reliable packet delivery over an unreliable network. Originally flow control of TCP was governed simply by the maximum allowed window size, advertised by the receiver and the policy that allowed the sender to send new packets only after receiving the acknowledgement for the previous packet. There has been a significant amount of research toward modelling variants of the Transmission Control Protocol (TCP) in order to understand the impact of this protocol on file transmission times and network utilization. TCP uses a network congestion avoidance algorithm that includes various aspects of an additive increase/multiplicative decrease (AIMD) scheme, with other schemes such as slow-start in order to achieve congestion avoidance. Among these TCP variants, TCP Vegas claims to have a better throughput [4]. Like other TCP congestion control algorithm, Vegas is purely a sender-side algorithm. TCP Vegas uses bandwidth estimation scheme to avoid congestion rather than waiting for congestion to happen to invokes its congestion control mechanism [5]. Like other TCP variants, TCP Vegas control the amount of data injected into the network by using two phases: slow start and congestion avoidance. TCP Vegas reduces queuing and packet loss, and thus reduces latency and increases overall throughput, by carefully matching the sending rate to the rate at which packets are successfully being drained by the network [12]. This paper simulates a computers network with TCP flows on simulation topology. Evaluation using simulation in specified network topologies helps understand the dynamics of the associated parameters in connection with TCP performance. The simulation of the network gives a better perspective on network functionality. With simulations help it is easier to reveal architecture and parameters influence on the network's behaviour. The previous studies [13] show the performance issue of TCP variants only on the basis of throughput and throughput fairness. This paper studies the network behaviour both in identical and cross-Variant congestion control in wired network. For these, not only throughput but also different performance criterions are considered to evaluate the performance of TCP Vegas, TCP Reno and TCP New Reno. One of the contributions in this paper is to show the network behavior through different performance criterion such as congestion window behaviour, packet loss, average throughput and transmission delay, jitter rate of TCP Variants in such a situation where they share the bottleneck link with TCP variants both in identical and cross-Variant wired network.
2020
A protocol is a set of rules that governs data communication which decides when to communicate, how to communicate and where to communicate and also what to communicate. One of them is Transmission Control Protocol (TCP) that is the most popular and known protocol for controlling of the data transmission from source to destination or from one node to another node. It gives the best results in offline streaming of the data as compared to User Datagram Protocol (UDP). Congestion is the mechanism in networking that takes place in the time of communication when the data exceeds from its actual limit and it becomes overhead then congestion problem occurs. It usually occurs on the network like if there exist a router then the overhead occurs on router when there is limited time-baud buffer due to which the data may loss or overhead occurs. For this solution TCP is the best option to control and avoid from this problem. In this paper, an analysis has been made with the help of TCP for examining the congestion control queuing mechanism. Along with that, some parameters have been taken into account take are throughput and delay. These parameters have been tested under different settings and have been showed that by utilizing TCP congestion control queuing approach high throughput and low delay of queuing has encountered. From OPNET simulation results it has been concluded that TCP have shown remarkable and outstanding performance for controlling congestion issue with the help of other existing schemes that has shown poor performance.
Recently, TCP incast problem in data center networks has attracted a wide range of industrial and academic attention. Lots of attempts have been made to address this problem through experiments and simulations. This paper analyzes the TCP incast problem in data centers by focusing on the relationships between the TCP throughput and the congestion control window size of TCP. The root cause of the TCP incast problem is explored and the essence of the current methods to mitigate the TCP incast is well explained. The rationality of our analysis is verified by simulations. The analysis as well as the simulation results provides significant implications to the TCP incast problem. Based on these implications, an effective approach named IDTCP (Incast Decrease TCP) is proposed to mitigate the TCP incast problem. Analysis and simulation results verify that our approach effectively mitigates the TCP incast problem and noticeably improves the TCP throughput.
The widely used reliable transport protocol TCP, is an end to end protocol designed for the wireline networks characterized by negligible random packet losses. This paper represents exploratory study of TCP congestion control principles and mechanisms. Modern implementations of TCP contain four intertwined algorithms: slow start, congestion avoidance, fast retransmit, and fast recovery. In addition to the standard algorithms used in common implementations of TCP, this paper also describes some of the more common proposals developed by researchers over the years. We also study, through extensive simulations, the performance characteristics of four representative TCP schemes, namely TCP Tahoe, New Reno and Vegas under the network conditions of bottleneck link capacities for wired network.
2010
This paper designs a novel congestion control algorithm named application based rate controllable TCP (ABC-TCP), whose transfer rate can be adjusted by the applications. If the required transfer rate doesn't meet the requirement of the application, the sender's congestion control window (CWND) will increase aggressively and if it gets the required transfer rate the congestion control window will stop growing, in which way to ensure the required transfer rate. ABC-TCP is implemented by modifying TCP code in Linux. Experiments on an FLDnet test-bed show that ABC-TCP is able to keep a stable throughput and satisfy critical application's needs.
2011
Transmission Control Protocol (TCP) is a basic communication language and a connection oriented protocol tied with transport layer consists of collection of rules and procedures to control communication between links. There are many TCP variants that modified and developed with respectively with the communications needs. Most of TCP current versions are include set of algorithms which built to control the congestion in critical links of network with maintaining the network throughput. In present years, TCP has been faced the fast growth in internet in parallel with the demand increasing to transfer the media on high speed links supported TCP. In the last years, computer networks and mobile cellular systems have qualified incredible evolution and a lot of computers and other user equipment's become linked together with most mutual protocol stack used being TCP . Currently, it is hard to recognize the congestion control mechanisms that are applied by different engines in Internet. One more imperative problem is the manner that these mechanisms are employed in diverse operating systems. The greatest universal transport protocol involved is the TCP and in the original accomplishment of TCP, a very small number of variants were done to minimalize the congestion in network path. Employment used accumulative confident acknowledgements and the expiration of a retransmission timer to afford reliability based on a modest go-back-n model. Some successive variants of TCP grounded on the mechanisms of congestion control and avoidance have been proposed and established. This article introducing a study and background to the performance of different congestion control mechanisms with various TCP variants and provide an investigation to the behavior for each mechanism.
TCP or Transmission Control Protocol represents one of the prevailing ''languages'' of the Internet Protocol Suite, complementing the Internet Protocol (IP), and therefore the entire suite is commonly referred to as TCP/IP. TCP provides reliability to data transferring in all end-to-end data stream services on the internet. This protocol is utilized by major internet applications such as the e-mail, file transfer, remote administration and world-wide-web. Other applications which do not require reliable data stream service may use the User Datagram Protocol (UDP), which provides a datagram service that emphasizes reduced latency over reliability. The task of determining the available bandwidth of TCP packets flow is in fact, very tedious and complicated. The complexity arises due to the effects of congestion control of both the network dynamics and TCP. Congestion control is an approved mechanism used to detect the optimum bandwidth in which the packets are to be sent by TCP sender. The understanding of TCP behaviour and the approaches used to enhance the performance of TCP in fact, still remain a major challenge. In conjunction to this, a considerable amount of researches has been made, in view of developing a good mechanism to raise the efficiency of TCP performance. The article analyses and investigates the congestion control technique applied by TCP, and indicates the main parameters and requirements required to design and develop a new congestion control mechanism.
Communications and Network, 2011
Transmission control protocol (TCP) has undergone several transformations. Several proposals have been put forward to change the mechanisms of TCP congestion control to improve its performance. A line of research tends to reduce speed in the face of congestion thereby penalizing itself. In this group are the window based congestion control algorithms that use the size of congestion window to determine transmission speed. The two main algorithm of window based congestion control are the congestion avoidance and the slow start. The aim of this study is to survey the various modifications of window based congestion control. Much work has been done on congestion avoidance hence specific attention is placed on the slow start in order to motivate a new direction of research in network utility maximization. Mathematical modeling of the internet is discussed and proposals to improve TCP startup were reviewed. There are three lines of research on the improvement of slow start. A group uses the estimation of certain parameters to determine initial speed. The second group uses bandwidth estimation while the last group uses explicit request for network assistance to determine initial startup speed. The problems of each proposal are analyzed and a multiple startup for TCP is proposed. Multiple startups for TCP specify that startup speed is selectable from an n-arry set of algorithms. We then introduced the e-speed start which uses the prevailing network condition to determine a suitable starting speed.
Journal of Network and Information Security, 2020
As we know Transmission Control Protocol (TCP) is improving itself with the help of many researchers working in this area all over the World. Many papers and proposals have been submitted by the different researchers to improve the performance of TCP by the congestion control mechanism. In this concern paper, we are able to improve the transmission speed through the window size congestion control technique which is playing an important role in the field of communication. As we already know there are two main important techniques to overcome the congestion and these are the Avoidance algorithm and Slow start mechanism. Now to specify the TCP there are multiple start-ups are existing to specify that start-up speed is selectable from an n-array set of algorithms. If well work and implement these algorithms we can improve our performance and control the congestion. This paper provide the depth analysis of the existing congestion control techniques and provide the model which is helpful to control congestion.
11th International Conference on Parallel and Distributed Systems (ICPADS'05), 2005
In this article, we present a new slow-start variant, which improves the throughput of TCP Vegas, we call this new mechanism Gallop-Vegas which quickly ramps up to the available bandwidth and reduces the burstiness during the slow-start phase. Since TCP (Transmission Control Protocol) is known to send bursts of packets during its slowstart phase due to the fast increase of window size and the ACK-clock based transmission. This phenomenon causes TCP Vegas to change from slow-start phase to congestionavoidance phase too early in the large BDP (bandwidthdelay product) links. Therefore, in Gallop-Vegas, we increase the congestion window size with a rate between exponential growth and linear growth during slow-start phase. Our extensive simulation results show that Gallop-Vegas significantly improves the performance during the slow-start phase. Furthermore, it is implementation feasible because only sending part needs to be modified.
2006
In this article, we present a new slow-start variant, which improves the throughput of transmission control protocol (TCP) Vegas. We call this new mechanism Gallop-Vegas because it quickly ramps up to the available bandwidth and reduces the burstiness during the slow-start phase. TCP is known to send bursts of packets during its slow-start phase due to the fast window increase and the ACK-clock based transmission. This phenomenon causes TCP Vegas to change from slow-start phase to congestionavoidance phase too early in the large bandwidth-delay product (BDP) links. Therefore, in Gallop-Vegas, we increase the congestion window size with a rate between exponential growth and linear growth during slow-start phase. Our analysis, simulation results, and measurements on the Internet show that Gallop-Vegas significantly improves the performance of a connection, especially during the slow-start phase. Furthermore, it is implementation feasible because only sending part needs to be modified.
2012 IEEE International Conference on Communications (ICC), 2012
Transmission Control Protocol (TCP) slow start degrades TCP performance under conditions of long-distance and high end-to-end latency, i.e., inherent characteristics of wide area networks (WANs). In this paper, we propose a new TCP slow start algorithm for WANs, called Adaptive Fast Start (AFStart), which incorporates an inline available bandwidth measurement over TCP technique into TCP slow start to set the slow start threshold adaptively and adjusts the congestion window intelligently. The performance of AFStart is evaluated through simulations using the dumb-bell topology and parking-lot topology by applying AFStart to Fast TCP. The simulation results show that AFStart can ramp up the congestion window from its initial value to the slow start threshold more quickly and smoothly than standard slow start, and AFStart achieves higher network link utilization and TCP throughput during the slow start than Fast TCP.
Computer Networks, 2011
Standard slow start does not work well under large bandwidthdelay product (BDP) networks. We find two causes of this problem in existing three popular operating systems, Linux, FreeBSD and Windows XP. The first cause is that because of the exponential increase of cwnd during standard slow start, heavy packet losses occur. Recovering from heavy packet losses puts extremely high load on end systems which renders the end systems completely unresponsive for a long time, resulting in a long blackout period of no transmission. This problem commonly occurs with the three operating systems. The second cause is that some of proprietary protocol optimizations applied for slow start by these operating systems to relieve the system load happen to slow down the loss recovery followed by slow start. To remedy this problem, we propose a new slow start algorithm, called Hybrid Start (HyStart) that finds a "safe" exit point of slow start at which slow start can finish and safely move to congestion avoidance without causing any heavy packet losses. HyStart uses ACK trains and RTT delay samples to detect whether (1) the forward path is congested or (2) the current size of congestion window has reached the available capacity of the forward path. HyStart is a plug-in to the TCP sender and does not require any change in TCP receivers. We implemented HyStart for TCP-NewReno and TCP-SACK in Linux and compare its performance with five different slow start schemes with the TCP receivers of the three different operating systems in the Internet and also in the lab testbeds. Our results indicate that HyStart works consistently well under diverse network environments including asymmetric links and high and low BDP networks. Especially with different operating system receivers (Windows XP and FreeBSD), HyStart improves the start-up throughput of TCP more than 2 to 3 times.
Workshop on High- …, 2003
2013
This paper discusses some Transmission Control Protocol (TCP) congestion control algorithm, and proposes increasing TCP’s initial congestion window to at least fifteen segments (about 25 KB). Transmission Control Protocol (TCP) flow start with an initial congestion window at most three (3) segments or about 4 KB of data. Most Web transactions are short-lived and TCP’s initial congestion window is a critical parameter in determining how quickly flows can finish. The rapid growth of the internet in terms of the volume of activity and traffic it carries over the past decades represents a remarkable example of the scalability of the internet architecture, which in spite of the growth, the standard TCP’s initial congestion value has not changed.
The demand for fast transfer of large volumes of data, and the deployment of the network infrastructures is ever increasing. However, the dominant transport protocol of today, TCP, does not meet this demand because it favors reliability over timeliness and fails to fully utilize the network capacity due to limitations of its conservative congestion control algorithm. The slow response of TCP in fast long distance networks leaves sizeable unused bandwidth in such networks. A large variety of TCP variants have been proposed to improve the connection's throughput by adopting more aggressive congestion control algorithms. Some of the flavors of TCP congestion control are loss-based, high-speed TCP congestion control algorithms that uses packet losses as an indication of congestion; delay-based TCP congestion control that emphasizes packet delay rather than packet loss as a signal to determine the rate at which to send packets. Some efforts combine the features of loss-based and delay-based algorithms to achieve fair bandwidth allocation and fairness among flows. A comparative analysis between different flavors of TCP congestion control namely Standard TCP congestion control (TCP Reno), loss-based TCP congestion control (HighSpeed TCP, Scalable TCP, CUBIC TCP), delay-based TCP congestion control (TCP Vegas) and mixed loss-delay based TCP congestion control (Compound TCP) is presented here in terns of congestion window verses elapsed time after the connection is established.
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