| Summary: | 博士 === 國立交通大學 === 資訊工程系 === 89 === In a broadband network, the flows of applications are allowed to request various amounts of bandwidth according to their requirements in the quality of service (QOS), evaluated in terms of delay, delay jitter (delay variance), and loss. A network service provider should provide a mechanism to achieve fair bandwidth allocation among flows according to their requirements. Our research focuses on providing efficient fair-allocation schemes for two main types of services, the circuit mode and the controlled-loss services. The circuit mode service aims to provide guaranteed bandwidth and delay bound while the controlled-loss service aims to enable flows to adjust their rates adapting to the network state for avoiding data loss. There have been such kinds of services defined in the ATM and the Internet. For example, in the Internet, the Guaranteed and Control-load services are the circuit mode and packet mode services, respectively. Two significant mechanisms of bandwidth allocation, Fair Queueing and Rate-based Congestion Control support circuit mode and controlled-load services, respectively. The common design issue of the two mechanisms is the fairness of bandwidth allocation. Fair allocation makes good separation between circuit mode applications and prevents the arguments of unfairness from packet mode applications. Based on Fair Queueing, we propose Bounded Tag Fair Queueing (BTFQ) scheme, which performs better in the three main issues of Fair Queueing: bounded unfairness, bounded packet delay, and computation efficiency. In addition, the enhanced version BTFQ+ is also proposed to improve the fairness property of BTFQ and a low-cost, high-speed hardware is designed for reducing computation time.
Based on Rate-based Congestion Control, we propose Weighted Max-min Fairness with Queue Control scheme (WMFQC). The scheme guarantees minimum rates of flows and distributes the available bandwidth fairly to flows much quickly. Once the rates of flows are reduced to their fair allocation shares, the packet loss will be reduced almost to zero. The queue control mechanism of the scheme also helps to reduce the packet loss while the fair allocation is not achieved yet. As a result, the scheme introduces a very low degree of packet loss. In the future, we will study on the fairness of bandwidth allocation in the Internet introduced by the TCP Congestion Control mechanism. TCP Congestion Control is paid much attention to because it provides the controlled-loss service in the Internet. An unfairness phenomenon resulting from the popular version of the TCP Congestion Control mechanism has been known that for the TCP connections passing through the same bottleneck link, the one with a longer round-trip delay receives a smaller bandwidth share. We seek to find an algorithm based on TCP Congestion Control to replace the popular version of TCP Congestion Control in order to achieve fair allocation.
Abstract (in English)
Acknowledgements
Table of Contents
List of Tables
List of Figures
List of Symbols
Chapter 1. Introduction
Chapter 2. Survey of Related Works
2.1 Services
2.1.1 ATM Service
2.1.2 Internet Transport Service
2.1.3 Integrated Services/RSVP
2.1.4 Differentiated Services
2.2 Circuit Emulation
2.2.1 Time-frame Based Packet Scheduling
2.2.1.1 Stop-and-Go
2.2.1.2 Hierarchical Round Robin
2.2.2 Priority Based Packet Scheduling
2.2.2.1 Delay Earliest-Due-Date
2.2.2.2 Jitter Earliest-Due-Date
2.2.2.3 Rate-Controlled Static-Priority
2.2.2.4 Virtual Clock
2.2.2.5 Fair Queueing
2.2.3 Adopting Fair Queueing for Circuit Emulation
2.2.4 Related Works of Fair Queueing
2.3 Available Bandwidth Access
2.3.1 Rate-based Mechanisms with Explicit Feedback
2.3.2 Rate-based Mechanisms with Implicit Feedback
2.3.3 Window-based Mechanisms with Implicit Feedback
2.3.4 Window-based Mechanisms with Explicit Feedback
2.3.5 Related Works of Rate-based Congestion Control
Chapter 3. Bounded Tag Fair Queueing
3.1 Fair Queueing
3.1.1 System Model
3.1.2 Goal of Fair Queueing
3.1.3 Theoretic Scheme for Fair Queueing
3.2 Bounded Tag Fair Queueing Scheme
3.2.1 Bounded Delay of BTFQ
3.2.2 Fairness of BTFQ
3.2.3 Efficiency of BTFQ
3.3 BTFQ+
3.3.1 Supporting Hardware for BTFQ+
3.4 Comparison
3.4.1 Classification and Comparison
3.4.2 Comparison with the SPFQ Scheme
3.4.3 Comparison with the LFVC Scheme
3.5 Simulation and Results
3.5.1 Fairness Degree
3.5.2 Experiments
3.6 Summary
Chapter 4. Weighted Max-min Fairness with Queue Control
4.1 Background
4.1.1 Rate-adaptive Mechanism
4.1.2 Switch Model
4.1.3 Max-Min Scheme
4.2 Weighted Max-min Fairness with Queue Control Scheme
4.2.1 Bandwidth Allocation
4.2.2 Queue Control
4.3 Correctness in Fairness
4.4 Simulation
4.4.1 Efficiency of WMFQC Scheme
4.4.2 Performance of WMFQC Scheme
4.5 Summary
Chapter 5. Concluding Remarks and Future Works
5.1 Concluding Remarks
5.2 Future Works
Reference
Appendix
Publication List
Vita
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