Wan, Wing San. / "September 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (p. 53-55). / Abstracts in English and Chinese. / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.iv / Contents --- p.v / Chapter Chapter 1 --- INTRODUCTION --- p.1 / Chapter Chapter 2 --- BACKGROUND AND RELATED WORK --- p.4 / Chapter 2.1 --- Sender-receiver-based approaches --- p.4 / Chapter 2.2 --- Sender-based approaches --- p.5 / Chapter 2.3 --- Receiver-based approaches --- p.6 / Chapter Chapter 3 --- TCP FLOW CONTROL REVISITED --- p.8 / Chapter Chapter 4 --- OPPORTUNISTIC TRANSMISSION --- p.12 / Chapter 4.1 --- Link bandwidth estimation --- p.16 / Chapter 4.2 --- Reception rate estimation --- p.18 / Chapter 4.3 --- Transmission scheduling --- p.19 / Chapter 4.4 --- Performance --- p.21 / Chapter Chapter 5 --- Local Retransmission --- p.23 / Chapter 5.1 --- The blackout period --- p.24 / Chapter 5.2 --- Proactive retransmission --- p.28 / Chapter 5.3 --- Performance --- p.30 / Chapter Chapter 6 --- Loss Event Suppression --- p.31 / Chapter 6.1 --- RTT modulation --- p.32 / Chapter 6.2 --- Performance --- p.35 / Chapter Chapter 7 --- Fairness --- p.37 / Chapter 7.1 --- Packet forwarding --- p.37 / Chapter 7.2 --- Non-uniform bandwidth allocation --- p.41 / Chapter Chapter 8 --- EXPERIMENTS --- p.43 / Chapter 8.1 --- Experiment setup --- p.43 / Chapter 8.2 --- Packet loss --- p.44 / Chapter 8.3 --- Unaccelerated TCP throughput --- p.45 / Chapter 8.4 --- Accelerated TCP throughput --- p.46 / Chapter 8.5 --- Fairness --- p.47 / Chapter 8.6 --- Mobile handset performance --- p.47 / Chapter Chapter 9 --- FUTURE WORK --- p.49 / Chapter 9.1 --- Dynamic AWnd control --- p.49 / Chapter 9.2 --- Split-TCP --- p.50 / Chapter 9.3 --- Dynamic resource allocation --- p.50 / Chapter 9.4 --- Sender-based acceleration --- p.51 / Chapter Chapter 10 --- CONCLUSION --- p.52 / BIBLIOGRAPHY --- p.53

Yeung, Fei-Fei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 144-146). / Abstracts in English and Chinese. / Introduction --- p.1 / Chapter Part I: --- A New Socket API for Enhancing Server Efficiency --- p.5 / Chapter Chapter 1 --- Introduction --- p.6 / Chapter 1.1 --- Brief Background --- p.6 / Chapter 1.2 --- Deficiencies of Nagle's Algorithm and Goals and Objectives of this Research --- p.7 / Chapter 1.2.1 --- Effectiveness of Nagle's Algorithm --- p.7 / Chapter 1.2.2 --- Preventing Small Packets via Application Layer --- p.9 / Chapter 1.2.3 --- Minimum Delay in TCP Buffer --- p.10 / Chapter 1.2.4 --- Maximum Delay in TCP Buffer --- p.11 / Chapter 1.2.5 --- New Socket API --- p.12 / Chapter 1.3 --- Scope of Research and Summary of Contributions --- p.12 / Chapter 1.4 --- Organization of Part 1 --- p.13 / Chapter Chapter 2 --- Background --- p.14 / Chapter 2.1 --- Review of Nagle's Algorithm --- p.14 / Chapter 2.2 --- Additional Problems Inherent in Nagle's Algorithm --- p.17 / Chapter 2.3 --- Previous Proposed Modifications on Nagle's Algorithm --- p.22 / Chapter 2.3.1 --- The Minshall Modification --- p.22 / Chapter 2.3.1.1 --- The Minshall Modification --- p.22 / Chapter 2.3.1.2 --- The Minshall et al. Modification --- p.23 / Chapter 2.3.2 --- The Borman Modification --- p.23 / Chapter 2.3.3 --- The Jeffrey et al. Modification --- p.25 / Chapter 2.3.3.1 --- The EOM and MORE Variants --- p.25 / Chapter 2.3.3.2 --- The DLDET Variant --- p.26 / Chapter 2.3.4 --- Comparison Between Our Proposal and Related Works --- p.26 / Chapter Chapter 3 --- Min-Delay-Max-Delay TCP Buffering --- p.28 / Chapter 3.1 --- Minimum Delay --- p.29 / Chapter 3.1.1 --- Why Enabling Nagle's Algorithm Alone is Not a Solution? --- p.29 / Chapter 3.1.2 --- Advantages of Min-Delay TCP-layer Buffering versus Application-layer Buffering --- p.30 / Chapter 3.2 --- Maximum Delay --- p.32 / Chapter 3.2.1 --- Why Enabling Nagle's Algorithm Alone is Not a Solution? --- p.32 / Chapter 3.2.2 --- Advantages of Max-delay TCP Buffering versus Nagle's Algorithm --- p.33 / Chapter 3.3 --- Interaction with Nagle's Algorithm --- p.34 / Chapter 3.4 --- When to Apply Our Proposed Scheme? --- p.36 / Chapter 3.5 --- New Socket Option Description --- p.38 / Chapter 3.6 --- Implementation --- p.40 / Chapter 3.6.1 --- Small Packet Transmission Decision Logic --- p.42 / Chapter 3.6.2 --- Modified API --- p.44 / Chapter Chapter 4 --- Experiments --- p.46 / Chapter 4.1 --- The Effect of Kernel Buffering Mechanism on the Service Time --- p.47 / Chapter 4.1.1 --- Aims and Methodology --- p.47 / Chapter 4.1.2 --- Comparison of Transmission Time Required --- p.49 / Chapter 4.2 --- Performance of Min-Delay-Max-Delay Scheme --- p.56 / Chapter 4.2.1 --- Methodology --- p.56 / Chapter 4.2.1.1 --- Network Setup --- p.56 / Chapter 4.2.1.2 --- Traffic Model --- p.58 / Chapter 4.2.1.3 --- Delay Measurement --- p.60 / Chapter 4.2.2 --- Efficiency of Busy Server --- p.62 / Chapter 4.2.2.1 --- Performance of Nagle's algorithm --- p.62 / Chapter 4.2.2.2 --- Performance of Min-Delay TCP Buffering Scheme --- p.67 / Chapter 4.2.3 --- Limiting Delay by Setting TCP´ؤMAXDELAY --- p.70 / Chapter 4.3 --- Performance Sensitivity Discussion --- p.77 / Chapter 4.3.1 --- Sensitivity to Data Size per Invocation of send() --- p.77 / Chapter 4.3.2 --- Sensitivity to Minimum Delay --- p.83 / Chapter 4.3.3 --- Sensitivity to Round Trip Time --- p.85 / Chapter Chapter 5 --- Conclusion --- p.88 / Chapter Part II: --- Two Analytical Models for a Refined TCP Algorithm (TCP Veno) for Wired/Wireless Networks --- p.91 / Chapter Chapter 1 --- Introduction --- p.92 / Chapter 1.1 --- Brief Background --- p.92 / Chapter 1.2 --- Motivation and Two Analytical Models --- p.95 / Chapter 1.3 --- Organization of Part II --- p.96 / Chapter Chapter 2 --- Background --- p.97 / Chapter 2.1 --- TCP Veno Algorithm --- p.97 / Chapter 2.1.1 --- Packet Loss Type Identification --- p.97 / Chapter 2.1.2 --- Refined AIMD Algorithm --- p.99 / Chapter 2.1.2.1 --- Random Loss Management --- p.99 / Chapter 2.1.2.2 --- Congestion Management --- p.100 / Chapter 2.2 --- A Simple Model of TCP Reno --- p.101 / Chapter 2.3 --- Stochastic Modeling of TCP Reno over Lossy Channels --- p.103 / Chapter Chapter 3 --- Two Analytical Models --- p.104 / Chapter 3.1 --- Simple Model --- p.104 / Chapter 3.1.1 --- Random-loss Only Case --- p.105 / Chapter 3.1.2 --- Congestion-loss Only Case --- p.108 / Chapter 3.1.3 --- The General Case (Random + Congestion Loss) --- p.110 / Chapter 3.2 --- Markov Model --- p.115 / Chapter 3.2.1 --- Congestion Window Evolution --- p.115 / Chapter 3.2.2 --- Average Throughput Formulating --- p.119 / Chapter 3.2.2.1 --- Random-loss Only Case --- p.120 / Chapter 3.2.2.2 --- Congestion-loss Only Case --- p.122 / Chapter 3.2.2.3 --- The General Case (Random + Congestion Loss) --- p.123 / Chapter Chapter 4 --- Comparison with Experimental Results and Discussions --- p.127 / Chapter 4.1 --- Throughput versus Random Loss Probability --- p.127 / Chapter 4.2 --- Throughput versus Normalized Buffer Size --- p.132 / Chapter 4.3 --- Throughput versus Bandwidth in Asymmetric Networks --- p.135 / Chapter 4.3 --- Summary --- p.136 / Chapter Chapter 5 --- Sensitivity of TCP Veno Throughput to Various Parameters --- p.137 / Chapter 5.1 --- Multiplicative Decrease Factor (α) --- p.137 / Chapter 5.2 --- Number of Backlogs (β) and Fractional Increase Factor (γ) --- p.139 / Chapter Chapter 6 --- Conclusions --- p.142 / Bibliography --- p.144

Ma Ke. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 64-68). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Motivation --- p.2 / Chapter 1.3 --- Contribution --- p.3 / Chapter 1.4 --- Organization --- p.4 / Chapter 2 --- Literature Review --- p.5 / Chapter 2.1 --- Overview --- p.5 / Chapter 2.2 --- Multi-Path Routing --- p.6 / Chapter 2.2.1 --- OSPF-ECMP --- p.7 / Chapter 2.2.2 --- LFI --- p.7 / Chapter 2.2.3 --- QSMP and QDMP --- p.9 / Chapter 2.2.4 --- WDP --- p.10 / Chapter 2.2.5 --- DMPR --- p.11 / Chapter 2.2.6 --- Cidon's Analysis --- p.13 / Chapter 3 --- LSLF and SLSLF Conditions --- p.15 / Chapter 3.1 --- Problem Formulation --- p.15 / Chapter 3.2 --- LFI Conditions --- p.16 / Chapter 3.3 --- LSLF Conditions --- p.17 / Chapter 3.4 --- SLSLF Conditions --- p.20 / Chapter 4 --- Performance of LSLF and SLSLF --- p.24 / Chapter 4.1 --- Overview --- p.24 / Chapter 4.2 --- Numerical Results --- p.26 / Chapter 5 --- Analysis of Multi-path Routing --- p.42 / Chapter 5.1 --- Assumptions --- p.43 / Chapter 5.2 --- M/M/C/C Queueing System --- p.44 / Chapter 5.3 --- Performance Analysis --- p.48 / Chapter 5.3.1 --- "Case 1 Only QoS flows between (s, d) exist" --- p.48 / Chapter 5.3.2 --- Case 2 QoS flows between other SD pairs also exist --- p.50 / Chapter 5.3.3 --- Case 3 A QoS flow can try m times before it is dropped --- p.53 / Chapter 5.4 --- Numerical Results --- p.56 / Chapter 6 --- Conclusion --- p.62

In order to serve hundreds of millions of users, contemporary content providers employ tens of thousands of servers to scale their systems. The system software in these environments, however, is struggling to keep up with the increase in demand: contemporary network and storage stacks, as well as related APIs (e.g., BSD socket API) follow a `one-size-fits-all' design, heavily emphasising generality and feature richness at the cost of performance, leaving crucial hardware resources unexploited. Despite considerable prior research in improving I/O performance for conventional stacks, substantial hardware potential still remains unexploited because most of these proposals are fundamentally limited in their scope and effectiveness, as they still have to fit in a general-purpose design. In this dissertation, I argue that specialisation and microarchitectural awareness are necessary in system software design to effectively exploit hardware capabilities, and scale I/O performance. In particular, I argue that trading off generality and compatibility, allows us to radically re-architect the stack emphasising application-specific optimisations and efficient data movement throughout the hardware to improve performance. I first demonstrate that conventional general-purpose stacks fail to effectively utilise contemporary hardware while serving critical Internet workloads, and show why modern microarchitectural properties play a critical role in scaling I/O performance. I then identify core decisions in Operating Systems design that, although they were originally introduced to optimise performance, are now proven redundant or even detrimental. I propose clean-slate, specialised architectures for network and storage stacks designed to exploit modern hardware properties, and application domain-specific knowledge in order to sidestep historical bottlenecks in systems I/O performance, and achieve great scalability. With thorough evaluation of my systems, I illustrate how specialisation and greater microarchitectural awareness could lead to dramatic performance improvements, which could ultimately translate to improved scalability and reduced capital expenditure simultaneously.

Chen, Liang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 87-91). / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Problem --- p.1 / Chapter 1.2 --- Motivation --- p.3 / Chapter 1.3 --- Thesis Contribution and Organization --- p.5 / Chapter 2 --- Background Study --- p.9 / Chapter 2.1 --- TFRC --- p.9 / Chapter 2.2 --- Related Work --- p.11 / Chapter 3 --- Network Modeling --- p.15 / Chapter 3.1 --- Network Utility Maximization Framework --- p.15 / Chapter 3.1.1 --- Primal Algorithm --- p.16 / Chapter 3.1.2 --- Dual Algorithm --- p.17 / Chapter 3.2 --- Overview of TCP Reno Modeling --- p.18 / Chapter 3.3 --- Modeling TFRC --- p.19 / Chapter 3.3.1 --- TFRC Model I --- p.20 / Chapter 3.3.2 --- TFRC Model II --- p.21 / Chapter 3.4 --- Modeling Coexistence Case --- p.23 / Chapter 4 --- Stability Analysis --- p.27 / Chapter 4.1 --- TFRC Network --- p.27 / Chapter 4.1.1 --- Global Stability --- p.28 / Chapter 4.1.2 --- Rate of Convergence --- p.32 / Chapter 4.1.3 --- Rate-adaptation Comparison --- p.36 / Chapter 4.2 --- TCP Reno and TFRC Coexistence Network --- p.40 / Chapter 4.2.1 --- Existence and Uniqueness of Equilibrium --- p.40 / Chapter 4.2.2 --- Stability Analysis of the Coexistence Case --- p.41 / Chapter 5 --- Delay Analysis --- p.45 / Chapter 5.1 --- TFRC Network Model I --- p.46 / Chapter 5.2 --- TFRC Network Model II --- p.51 / Chapter 5.3 --- Robustness Comparison of TCP and TFRC --- p.55 / Chapter 6 --- Simulation Results --- p.61 / Chapter 6.1 --- Matlab Simulations --- p.61 / Chapter 6.1.1 --- Smoothed Effects and Rate Convergence --- p.61 / Chapter 6.1.2 --- Rate-adaptation Comparison of Two Models --- p.64 / Chapter 6.1.3 --- Delay Instability --- p.65 / Chapter 6.2 --- NS2 Simulations --- p.69 / Chapter 6.2.1 --- Traffic Smoothness and Jitter Property --- p.70 / Chapter 6.2.2 --- Necessity of Adaptive Scheme --- p.73 / Chapter 7 --- Conclusion --- p.77 / Chapter A --- Appendix --- p.81 / Chapter A.l --- Delay Analysis for the Single Link Case of TFRC I --- p.81 / Chapter A.2 --- Delay Analysis for the Single Link Case of TFRC II --- p.84 / Bibliography --- p.87

Chen, Wei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 64-67). / Abstracts in English and Chinese. / Dedication --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Contributions --- p.2 / Chapter 1.3 --- Thesis Organization --- p.3 / Chapter 2 --- Related Work --- p.4 / Chapter 2.1 --- Previous Work on Rate Control and link Scheduling in Wireless Networks --- p.4 / Chapter 2.2 --- Previous Work on Multi-connection TCP --- p.6 / Chapter 2.3 --- Previous Work on AQM --- p.6 / Chapter 3 --- Problem Settings --- p.7 / Chapter 3.1 --- Network Modeling --- p.7 / Chapter 3.2 --- Capacity Region of Wireless Networks and Throughput-optimal Scheduling --- p.9 / Chapter 3.3 --- Throughput-optimality of A-CSMA --- p.10 / Chapter 3.4 --- TCP Reno Congestion Control Modeling --- p.11 / Chapter 4 --- Starvation of TCP Reno over L-CSMA and A-CSMA --- p.13 / Chapter 4.1 --- TCP Reno Starves over L-CSMA --- p.13 / Chapter 4.2 --- TCP Reno Starves over A-CSMA --- p.15 / Chapter 4.2.1 --- Simulations --- p.15 / Chapter 4.2.2 --- Observations and Explanations --- p.17 / Chapter 5 --- Analysis and Our Proposed Solution --- p.19 / Chapter 5.1 --- Proposed Solution: Multi-connection TCP Reno Scheme --- p.19 / Chapter 5.2 --- Implementation --- p.25 / Chapter 5.3 --- Discussion --- p.28 / Chapter 5.3.1 --- Achieve Arbitrary Utility --- p.28 / Chapter 5.3.2 --- Extension to Networks with Both Wired and Wireless Links --- p.28 / Chapter 5.3.3 --- Impact of ACK Traffic --- p.30 / Chapter 5.3.4 --- Tradeoff between performance and overhead --- p.31 / Chapter 5.3.5 --- Overhead of Multi-connection TCP --- p.32 / Chapter 6 --- Simulations --- p.37 / Chapter 6.1 --- Single-hop Wireless Networks Scenario --- p.38 / Chapter 6.1.1 --- Fairness and Throughput --- p.38 / Chapter 6.1.2 --- Impact of Measuring Queue Length in Number of Bytes for n-ACK --- p.42 / Chapter 6.1.3 --- Impact of Dummy Packets --- p.43 / Chapter 6.1.4 --- Impact of Product k2β --- p.45 / Chapter 6.1.5 --- Effects of Parameterβ --- p.47 / Chapter 6.1.6 --- Effects of Parameter k --- p.49 / Chapter 6.1.7 --- Overhead of n-ACK Solution --- p.50 / Chapter 6.2 --- Multihop Wireless Networks Scenario --- p.52 / Chapter 6.3 --- Multihop Networks with Wireless and Wired Links Scenario --- p.53 / Chapter 7 --- Conclusions and Future Work --- p.56 / Chapter 7.1 --- Conclusions --- p.56 / Chapter 7.2 --- Future Work --- p.57 / Chapter A --- Explanation to Starvation of TCP Reno over A-CSMA --- p.58 / Chapter B --- TCP Reno over A-CSMA with AQM --- p.60 / Chapter B.1 --- TCP Reno starves --- p.60 / Chapter B.2 --- Explanation --- p.61 / Bibliography --- p.64

Tese de mestrado integrado. Engenharia Electrotécnica e de Computadores (Major Automação). Faculdade de Engenharia. Universidade do Porto. 2009

The main aim of the project is to launch multiple processes and have those processes communicate with each other using peer to peer communication to eliminate the problems of multiple processes running on a single server, and multiple processes running on inhomogeneous servers as well as the problems of scalability. This entire process is done using MPICH which is a high performance and portable implementation of Message Passing Interface standard. The project involves setting up the passwordless authentication between two local servers with the help of SSH connection. By establishing a peer to peer communication and by using a unique shell script which is written using MPICH and its derivatives, I am going to demonstrate the process of inter-process communication between the servers.

Voice over IP and video applications continue to increase the amount of traffic over the Internet. These applications utilize the UDP protocol because TCP is not suitable for streaming applications. The flow and congestion control mechanisms of TCP can change the connection transmission rate too drastically, affecting the user-perceived quality of the transmission. Also, the TCP protocol provides a level of reliability that may waste network resources, retransmitting packets that have no value. On the other hand, the use of end-to-end flow and congestion control mechanisms for streaming applications has been acknowledged as an important measure to ease or eliminate the unfairness problem that exist when TCP and UDP share the same congested bottleneck link. Actually, router-based and end-to-end solutions have been proposed to solve this problem. This thesis introduces a new end-to-end protocol based on TCP SACK called SF-SACK that promises to be smooth enough for streaming applications while implementing the known flow and congestion control mechanisms available in TCP. Through simulations, it is shown that in terms of smoothness the SF-SACK protocol is considerably better than TCP SACK and only slightly worse than TFRC. Regarding friendliness, SF-SACK is not completely fair to TCP but considerably fairer than UDP. Furthermore, if SF-SACK is used by both streaming and data-oriented applications, complete fairness is achieved. In addition, SF-SACK only needs sender side modifcations and it is simpler than TFRC.

In recent times, the imminent lack of public IPv4 addresses has attracted the attention of both the research community and industry. The cellular industry has decided to combat this problem by using IPv6 for all new terminals. However, the success of 3G network deployment will depend on the services offered to end users. Currently, almost all services reside in the IPv4 address space, making them inaccessible to users in IPv6 networks. Thus, an intermediate translation mechanism is required. Previous studies on network address translation methods have shown that Realm Base Kluge Address Heuristic-IP, REBEKAH-IP supports all types of services that can be offered to IPv6 hosts from the public IPv4 based Internet, and provides excellent scalability. However, the method suffers from an ambiguity problem which may lead to call blocking. This thesis presents an improvement to REBEKAH-IP scheme in which the side effect is removed, creating a robust and fully scalable system. The improvement can be divided into two major tasks including a full investigation on the scalability of addressing and improvements to the REBEKAH-IP scheme that allow it to support important features such as ICMP and IP mobility. To address the first task a method called REBEKAH-IP with Port Extension (RPX) is introduced. RPX is extended from the original REBEKAH-IP scheme to incorporate centralised management of both IP address and port numbers. This method overcomes the ambiguity problem, and improves scalability. We propose a priority queue algorithm to further increase scalability. Finally, we present extensive simulation results on the practical scalability of RPX with different traffic compositions, to provide a guideline of the expected scalability in large-scale networks. The second task concerns enabling IP based communication. Firstly, we propose an ICMP translation mechanism which allows the RPX server to support important end-toend control functions. Secondly, we extend the RPX scheme with a mobility support scheme based on Mobile IP. In addition, we have augmented Mobile IP with a new tunneling mechanism called IP-in-FQDN tunneling. The mechanism allows for unique mapping despite the sharing of IP addresses while maintaining the scalability of RPX. We examine the viability of our design through our experimental implementation.