Evaluation of the Effectiveness of ACK Filtering and ACK Congestion Control in Mitigating the Effects of Bandwidth Asymmetry

The user demand for high speed and ubiquitous connectivity has led to the development and deployment of many new technologies, such as DSL and satellite-based networks, for accessing the Internet network. The goal of these technologies is to mitigate the bottleneck. Other technologies, such as wireless and packet radio networks aimed at providing the user with unrestricted access to their mobile devices and the Internet. Given that these networks are increasingly being deployed as high-speed access networks, it is highly desirable to achieve good network performance over such networks. These technologies show different characteristics (asymmetry) in uplink and downlink directions. Network asymmetry (uneven bandwidth) can negatively affect the performance of feedback-based transport protocol such as Transmission Control Protocol (TCP). This is because that congestion in any direction can affect the flow of feedback in the other direction. ACK Filtering and ACK Congestion Control techniques are used to diminish the congestion on the upstream link. These techniques suffer from sender burstiness and a slowdown in congestion window growth problems. This project addresses the TCP performance problems caused by network asymmetry and discuss the reasons for the inapplicability between TCP and asymmetric networks. It studies the effectiveness of these techniques in mitigating the effects of bandwidth asymmetry in TCP/IP networks and provides suggestions to overcome the problems associated with these techniques. Based on the performance model presented in this project, achieving optimum TCP performance under different asymmetric conditions is described

TCP-Swift: An end-host enhancement scheme for TCP over satellite IP networks

A new transport layer protocol called TCP-Swift is proposed for enhancing the TCP performance over satellite IP networks. TCP-Swift replaces the conventional TCP slow start and fast recovery algorithms by speedy start and speedy recovery. With speedy start, a TCP-Swift sender opens up its congestion window in only two round trip times. This significantly shortens the time needed in probing the network for equilibrium state. With speedy recovery, we can infer the cause of a packet loss by observing the ACK stream received at the sender. If the loss is due to wireless transmission error, the sender's congestion window can be re-opened up more aggressively to fully utilize the available satellite link bandwidth. We show that TCP-Swift outperforms existing TCP schemes by simulations.published_or_final_versio

Online Identification of Last-Mile Throughput Bottlenecks on Home Routers

Supervisors: Renata Teixeira (Inria) , Promethee Spathis (UPMC)Advisors: Anna-Kaisa Pietilainen (Inria) , Srikanth Sundaresan (Samsara Networks/ICSI), Nick Feamster (Princeton University)International audienceWe develop a system that runs online on commodity home routers to locate last-mile throughput bottlenecks to the home wireless network or the access ISP. Pinpointing whether the home wireless or the access ISP bottlenecks Internet through-put is valuable for home users who want to better troubleshoot their Internet experience; for access ISPs that receive numerous calls from frustrated home customers; and for informing the debate on regulating the residential broadband market. Developing such a system is challenging because commodity home routers have limited resources. The main contribution of this thesis is to develop a last-mile throughput bottleneck detection algorithm that relies solely on lightweight metrics available in commodity home routers. Our evaluation shows that our system accurately locates last-mile bottlenecks on commodity home routers with little performance degradation

Enhancing TCP Performance in Mobile Ad Hoc Network Using Explicit Link Failure Notification (ELFN)

The dynamics and the unpredictable behaviour of a wireless mobile ad hoc network results in the hindrance of providing adequate reliability to network connections. Frequent route changes in the network relatively introduce incessant link failures which eventually degrade TCP performance considerably. In this research, we are going to study the potential improvement of TCP performance when Explicit Link Failure Notification is implemented as opposed to the standard TCP mechanism. ELFN modifies the ‘slow start’ mechanism that is used in standard TCP so that the throughput achieved from the network can be maximized

A Rate-based TCP Congestion Control Framework for Cellular Data Networks

Ph.DDOCTOR OF PHILOSOPH

Satellite Networks: Architectures, Applications, and Technologies

Since global satellite networks are moving to the forefront in enhancing the national and global information infrastructures due to communication satellites' unique networking characteristics, a workshop was organized to assess the progress made to date and chart the future. This workshop provided the forum to assess the current state-of-the-art, identify key issues, and highlight the emerging trends in the next-generation architectures, data protocol development, communication interoperability, and applications. Presentations on overview, state-of-the-art in research, development, deployment and applications and future trends on satellite networks are assembled

When Latency Matters: Measurements and Lessons Learned

Several emerging classes of interactive applications are demanding for extremely low-latency to be fully unleashed, with edge computing generally regarded as a key enabler thanks to reduced delays. This paper presents the outcome of a large-scale end-to-end measurement campaign focusing on task-offloading scenarios, showing that moving the computation closer to the end-users, alone, may turn out not to be enough. Indeed, the complexity associated with modern networks, both at the access and in the core, the behavior of the protocols at different levels of the stack, as well as the orchestration platforms used in data-centers hide a set of pitfalls potentially reverting the benefits introduced by low propagation delays. In short, we highlight how ensuring good QoS to latency-sensitive applications is definitely a multi-dimensional problem, requiring to cope with a great deal of customization and cooperation to get the best from the underlying network

Mitigating TCP Degradation over Intermittent Link Failures Using Intermediate Buffers

This thesis addresses the improvement of data transmission performance in a challenged network. It is well known that the popular Transmission Control Protocol degrades in environments where one or more of the links along the route is intermittently available. To avoid this degradation, this thesis proposes placing at least one node along the path of transmission to buffer and retransmit as needed to overcome the intermittent link. In the four-node, three-link testbed under particular conditions, file transmission time was reduced 20 fold in the case of an intermittent second link when the second node strategically buffers for retransmission opportunity

STCP: A New Transport Protocol for High-Speed Networks

Transmission Control Protocol (TCP) is the dominant transport protocol today and likely to be adopted in future high‐speed and optical networks. A number of literature works have been done to modify or tune the Additive Increase Multiplicative Decrease (AIMD) principle in TCP to enhance the network performance. In this work, to efficiently take advantage of the available high bandwidth from the high‐speed and optical infrastructures, we propose a Stratified TCP (STCP) employing parallel virtual transmission layers in high‐speed networks. In this technique, the AIMD principle of TCP is modified to make more aggressive and efficient probing of the available link bandwidth, which in turn increases the performance. Simulation results show that STCP offers a considerable improvement in performance when compared with other TCP variants such as the conventional TCP protocol and Layered TCP (LTCP)