Thesis (M.S.)--Baylor University, 2006. / Includes bibliographical references (p. 50-52).

This dissertation is concerned with the management and performance issues of those register-insertion (R-I) ring type local area networks (LANs) which employ the message removal by destination node protocol. A typical example of such a network is the Distributed Loop Computer Network (DLCN). developed by Liu et al for fundamental research in the field of distributed computing. After considering the management issues of low cost R-J LANs. the research deals with performance analysis of the dynamically reconfigurable register-insertion (DRR) network. In the first part of this research. a set of management functions is identified which are desirable and can be provided economically by a low cost LAN. A unique feature of the DLCN is that messages are removed from the network by the destination node. that is. messages do not travel whole of the loop. Therefore. it is not possible for a special control node to monitor the data traffic on the network without providing support functionality in each network access unit (NAU). The minimum functionality which must be provided in each NAU is identified in the thesis. A skeleton network was implemented to verify the feasibility of the proposed scheme. A paper describing the findings of this research was published and is reproduced as appendix A. In the second part of this research. a new feature of the DLCN network is introduced. namely. that the performance of a network employing removal by destination protocol can be improved by reconfiguring the network in a particular way. A methodology to find the optimal configuration is developed and is shown. by worked examples. to lead to improved performance. The findings of this research are particularly applicable to the dynamically reconfigurable register-insertion (DRR) network. A paper dealing with the optimisation of a hypothetical fully connected DRR network has been accepted for publication. Another paper. which considers the general case of less than fully connected DRR networks. is to be published. Both papers are reproduced as append ices Band C. Finally. a performance study of the ORR network is undertaken. As there seems to be no published attempt at formal analysis or simulation of a ORR network. a survey of literature dealing with performance study of the basic OLeN is performed. A simulation model of the DRR was then developed and implemented to verify the results arrived at in the previous section. Later. a queueing model of the DRR network. based on the work of Bux and Schlatter [7] is developed and analysed. Both simulation and analysis support the claim that the performance of a DRR network can be improved by adopting the configuration strategy developed in this thesis.

This thesis discusses the problems of the conventional ISO 9646 methodology for OSI conformance testing, and proposes a new methodology based on trace analysis. In the proposed methodology, a trace analyzer is used to determine whether the observed behavior of the implementation under test is valid or invalid. This simplifies test cases dramatically, since they now need only specify the expected behavior of the IUT; unexpected behavior is checked by the trace analyzer. Test suites become correspondingly smaller. Because of this reduction in size and complexity, errors in test suites can be found and corrected far more easily. As a result, the reliability and the usefulness of the conformance testing process are greatly enhanced. In order to apply the proposed methodology, trace analyzers are needed. Existing trace analyzers are examined, and found to be unsuitable for OSI conformance testing. A family of new trace analysis algorithms is presented and proved. To verify the feasibility of the proposed methodology, and to demonstrate its benefits, it is applied to a particular protocol, the LAPB protocol specified by ISO 7776. The design and implementation of a trace analyzer for LAPB are described. The conventional ISO 8882-2 test suite for LAPB, when rewritten to specify only the expected behavior of the IUT, is found to be more than an order of magnitude smaller. / Science, Faculty of / Computer Science, Department of / Graduate

As Local Area Networks gain momentum in recent Computer Science research, implementation is generally characterized by various factors such as efficiency, reliability, error recovery, and synchronism; however, how well the above issues can be achieved is heavily dependent on the facilities available in an implementation environment. Due to the recent popularity of message passing and concurrent processes, the UNIX 4.2bsd operating system with its interprocess communication facility is chosen to be the implementation environment for the Cambridge Ring's Basic Block and Byte Stream Protocols. Basic Block Protocol, implemented as a device driver in the system kernel, is the lowest level protocol which provides an unreliable datagram service, while the Byte Stream Protocol, implemented using multi-concurrent processes in the user space, provides a reliable, full-duplex virtual circuit service based on the service provided by the Basic Block Protocol. This thesis describes the protocol implementation on a 68000 based SUN workstation, and discusses results learnt from the experiment. The multi-concurrent processes approach is found to work adequately well for a small number of clients, but incur high overhead when the number of clients is large. / Science, Faculty of / Computer Science, Department of / Graduate

This thesis addresses the problem of protocol verification. We first present a brief review of the existing specification methods for communication protocols, with emphasis on the hybrid techniques. The alternating bit protocol is specified in ISO/FDT, BBN/FST and UNISPEX to provide a comparison between three interesting hybrid models of protocol specification. A method for applying the unbounded state Temporal Logic to verify a protocol specified in a hybrid technique (in particular FDT) is outlined. Finally, a new specification and verification method called SETL is proposed, which is based on event sequences and temporal logic. To illustrate the method two data transfer protocols namely, the stop-wait and alternating bit protocols are specified in SETL and verified. We demonstrate that SETL is a generalization of the hybrid techniques, it is sound and that it can be semi-automated. / Science, Faculty of / Computer Science, Department of / Graduate

VALISYN, an automated system for the validation and synthesis of error-free protocols has been implemented in C language. It assists designers in the detection and prevention of various kinds of potential design errors, such as state deadlocks, non-executable interactions, unspecified receptions and state ambiguities. The technique employed is a stepwise application of a set of production rules which guarantee complete reception capability. These rules are implemented in a tracking algorithm, which prevents the formation of non-executable interactions and unspecified receptions, and which monitors the existence of state deadlocks and state ambiguities. The implementation of VALISYN is discussed and a number of protocol validation and synthesis examples are presented to illustrate its use and features. / Science, Faculty of / Computer Science, Department of / Graduate

published_or_final_version / Computer Science / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Network applications and Internet services fail all too frequently. However, end users cannot effectively identify the root cause using traditional troubleshooting techniques due to the limited capability to distinguish failures caused by local network elements from failures caused by elements located outside the local area network. To overcome these limitations, we propose a new approach, one that leverages collaboration of user machines to assist end users in diagnosing various failures related to Internet connectivity and poor network performance. First, we present DYSWIS ("Do You See What I See?"), an automatic network fault detection and diagnosis system for end users. DYSWIS identifies the root cause(s) of network faults using diagnostic rules that consider diverse information from multiple nodes. In addition, the DYSWIS rule system is specially designed to support crowdsourced and distributed probes. We also describe the architecture of DYSWIS and compare its performance with other tools. Finally, we demonstrate that the system successfully detects and diagnoses network failures which are difficult to diagnose using a single-user probe. Failures in lower layers of the protocol stack also have the potential to disrupt Internet access; for example, slow Internet connectivity is often caused by poor Wi-Fi performance. Channel contention and non-Wi-Fi interference are the primary reasons for this performance degradation. We investigate the characteristics of non-Wi-Fi interference that can severely degrade Wi-Fi performance and present WiSlow ("Why is my Wi-Fi slow?"), a software tool that diagnoses the root causes of poor Wi-Fi performance. WiSlow employs user-level network probes and leverages peer collaboration to identify the physical location of these causes. The software includes two principal methods: packet loss analysis and 802.11 ACK number analysis. When the issue is located near Wi-Fi devices, the accuracy of WiSlow exceeds 90%. Finally, we expand our collaborative approach to the Internet of Things (IoT) and propose a platform for network-troubleshooting on home devices. This platform takes advantage of built-in technology common to modern devices --- multiple communication interfaces. For example, when a home device has a problem with an interface it sends a probe request to other devices using an alternative interface. The system then exploits cooperation of both internal devices and remote machines. We show that this approach is useful in home networks by demonstrating an application that contains actual diagnostic algorithms.

by Wong Leung-Chung Chris. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 86-[92]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Routing Overview --- p.2 / Chapter 1.2 --- Routing in the Internet --- p.5 / Chapter 1.2.1 --- Inter-Domain Routing --- p.6 / Chapter 1.2.2 --- Intra-Domain Routing --- p.7 / Chapter 1.2.3 --- The Future Trend --- p.7 / Chapter 2 --- Inter-Domain Routing --- p.9 / Chapter 2.1 --- Inter-Domain Routing Protocols --- p.9 / Chapter 2.1.1 --- Exterior Gateway Protocol (EGP) --- p.10 / Chapter 2.1.2 --- Border Gateway Protocol (BGP) --- p.11 / Chapter 2.1.3 --- Inter-Domain Policy Routing (IDPR) --- p.12 / Chapter 2.1.4 --- Other Protocols --- p.13 / Chapter 2.2 --- The Need for Pricing on Inter-Domain Routing Protocols --- p.13 / Chapter 2.3 --- Pricing Scheme on the Inter-Domain level --- p.15 / Chapter 2.4 --- Routing Protocols to Support Pricing on the Internet --- p.16 / Chapter 2.4.1 --- Routing Towards Multiple-Additive Metrics --- p.16 / Chapter 2.4.2 --- "Network Model, Notations and Assumptions" --- p.16 / Chapter 2.4.3 --- The Problem Statement --- p.18 / Chapter 3 --- Application of Neural Nets in Route Selection --- p.20 / Chapter 3.1 --- Neural Network (NN) Overview --- p.20 / Chapter 3.1.1 --- Brief History on Neural Network Research --- p.20 / Chapter 3.1.2 --- Definition of Neural Network --- p.21 / Chapter 3.1.3 --- Neural Network Architectures --- p.22 / Chapter 3.1.4 --- Transfer Fucntion of a Neuron --- p.24 / Chapter 3.1.5 --- Learning Methods --- p.25 / Chapter 3.1.6 --- Applications in Telecommunications --- p.26 / Chapter 3.2 --- Review on the Applications of Neural Networks in Packet Routing --- p.27 / Chapter 3.2.1 --- The JEB Branch --- p.27 / Chapter 3.2.2 --- The Hopfield/Energy Minimization Branch (HEM) --- p.29 / Chapter 3.2.3 --- Supervised Learning (SL) --- p.34 / Chapter 3.3 --- Discussions --- p.35 / Chapter 4 --- Route Selection as “Link-state´ح Classification --- p.36 / Chapter 4.1 --- Multi-Layer Feedforward Network (MLFN) --- p.37 / Chapter 4.1.1 --- Function Approximation Power of MLFN --- p.38 / Chapter 4.1.2 --- Choosing MLFN parameters..........´ب --- p.40 / Chapter 4.1.3 --- Trailing a MLFN --- p.41 / Chapter 4.2 --- The Utility Function --- p.43 / Chapter 4.3 --- The Neural Network Architecture --- p.46 / Chapter 4.3.1 --- Routing Graph Representation with Successor Sequence Table (SST) --- p.46 / Chapter 4.3.2 --- The Neural Network Layout --- p.52 / Chapter 4.3.3 --- How the Neural Network Controller Works --- p.55 / Chapter 4.3.4 --- Training --- p.56 / Chapter 4.4 --- Simulation --- p.56 / Chapter 4.4.1 --- Performance Parameters --- p.56 / Chapter 4.4.2 --- Simulation Results --- p.57 / Chapter 4.5 --- Conclusions and Discussions --- p.70 / Chapter 5 --- Route Selection as Energy Minimization - A Theoretical Study --- p.73 / Chapter 5.1 --- The Hopfield/Tank NN Model --- p.73 / Chapter 5.2 --- Boltzman's Machine --- p.76 / Chapter 5.3 --- Boltzman's Machine Model for Multiple-Metrices Routing --- p.79 / Chapter 5.4 --- Conclusions --- p.82 / Chapter 6 --- Conclusions --- p.84 / Bibliography --- p.86