Selective Performance Enhancement of Traffic Flows

Lecture Notes in Computer Science, 2005

The use of multiple concurrent parallel TCP flows is an easy way to achieve higher speed reliable data transfers. However, parallel TCP flows are inherently unfair with respect to single TCP flows. We suggest a new scheme called TCP-P, which controls aggressiveness of a group of parallel TCP flows by regulating their total aggressiveness (or unfairness) to be comparable to a single TCP flow, or any multiple thereof. TCP-P makes a group of N parallel TCP flows appear to other flows like k separable TCP flows-i.e., have strength k-through appropriate manipulations of increase and decrease behavior of the congestion windows of the TCP flows in the group. We implemented our scheme as part of Linux and experimental results show that the proposed scheme effectively controls aggressiveness of parallel TCP flows.

SSRN Electronic Journal

This paper is an exploratory survey of TCP congestion control principles and techniques. In addition to the standard algorithms used in common software implementations of TCP, this paper also describes some of the more common proposals developed by researchers over the years. By studying congestion control techniques used in TCP implementation software and network hardware we can better comprehend the performance issues of packet switched networks and in particular, the public Internet

2001

2021

Introduction of new, more advanced services to the networking paradigm has led to an increased heterogeneity of media types and network traffic. Although several transport protocols have been developed over the years to cater to the Quality-of-Service requirements of these network services, the dynamic nature of the network condition is a variable that creates a hindrance in the mapping of an efficient transport protocol to a network service.Dynamic Protocol Selection can serve as a potential solution for this by applying innovative techniques to adaptively select among pre-existing transport protocols during run-time, thus catering to these requirements dynamically. Although the concept has been proven to be beneficial, there are certain research gaps that are yet to be addressed. In this thesis, we attempt to take a step forward to address a few of these research gaps. As a result, we designed a standardized conceptual framework (DPS framework) for the Dynamic Selection of various...

2000

To model possible suggested changes in TCP window adaptation in response to randomized feedback, such as ECN, we formulate a generalized version of the TCP congestion avoidance algorithm. We first consider multiple such generalized TCP flows sharing a bottleneck buffer under the Assured Service model and use a fixed point technique to obtain the mean window sizes and throughputs for the TCP flows. To further study how changes in the adaptation algorithm affect the variability in the throughput, we use an analytical-cum-numerical technique to derive the window distribution (and related statistics) of a single generalized flow under state-dependent randomized congestion feedback.

— 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.

2017 IEEE International Conference on Communications (ICC), 2017

HTTP Adaptive Streaming (HAS) is a widely used video streaming technology that suffers from a degradation of user's Quality of Experience (QoE) and network's Quality of Service (QoS) when many HAS players are sharing the same bottleneck link and competing for bandwidth. The two major factors of this degradation are: the large OFF period of HAS, which causes false bandwidth estimations, and the TCP congestion control, which is not suitable for HAS given that it does not consider the different video encoding bitrates of HAS. This paper proposes a HAS-based TCP congestion control, TcpHas, that minimizes the impact of the two aforementioned issues. It does this by using traffic shaping on the server. Simulations indicate that TcpHas improves both QoE, mainly by reducing instability, and QoS, mainly by reducing queuing delay and packet drop rate.

Transmission control protocol (TCP) provides a reliable data transfer in all end-to-end data stream services on the internet. There are some mechanisms that TCP has that make it suitable for this purpose. Over the years, there have been modifications in TCP algorithms starting from the basic TCP that has only slow-start and congestion avoidance algorithm to the modifications and additions of new algorithms. Today, TCP comes in various variants which include TCP Tahoe, Reno, new reno, vegas, sack etc. Each of this TCP variant has its peculiarities, merits and demerits. This paper is a review of four TCP variants, they are: TCP tahoe, Reno, new reno and vegas, their congestion avoidance algorithms, and possible future research areas.

IEEE/ACM Transactions on Networking, 1999

A large number of Internet applications are sensitive to overload conditions in the network. While these applications have been designed to adapt somewhat to the varying conditions in the Internet, they can bene t greatly from an increased level of predictability in network services. We propose minor extensions to the packet queueing and discard mechanisms used in routers, coupled with simple control mechanisms at the source that enable the network to guarantee minimal levels of throughput to di erent sessions while sharing the residual network capacity in a cooperative manner. The service realized by the proposed mechanisms is an interpretation of the controlled-load service being standardized by the ietf. Although controlled-load service can be used in conjunction with any transport protocol, our focus in this paper is on understanding its interaction with tcp. Speci cally, we study the dynamics of tcp tra c in an integrated services network that simultaneously supports both best-e ort and controlledload sessions. In light of this study, we propose and experiment with modi cations to tcp's congestion control mechanisms in order to improve its performance in networks where a minimum transmission rate is guaranteed. We then investigate the e ect of network transients, such as changes in tra c load and in service levels, on the performance of controlled-load as well as best-e ort connections. To capture the evolution of integrated services in the Internet, we also consider situations where only a selective set of routers are capable of providing service di erentiation between best-e ort and controlled-load tra c. Finally, we show how the service mechanisms proposed here can be embedded within other packet and link scheduling frameworks in a fully-evolved integrated services Internet.

Proceedings of the FREENIX Track: 2002 …, 2002

The TCP protocol is used by the majority of the net- work applications on the Internet. TCP performance is strongly influenced by its congestion control algo- rithms that limit the amount of transmitted traffic based on the estimated network capacity and utilization. Be- cause the freely available Linux operating system has gained popularity especially in the network servers, its TCP