Master of Science

The growing usage of computer networks is requiring improvements in network technologies and management techniques so users will receive high quality service. As more individuals transmit data through a computer network, the quality of service received by the users begins to degrade. A major aspect of computer networks that is vital to quality of service is data routing. A more effective method for routing data through a computer network can assist with the new problems being encountered with today's growing networks. Effective routing algorithms use various techniques to determine the most appropriate route for transmitting data. Determining the best route through a wide area network (WAN), requires the routing algorithm to obtain information concerning all of the nodes, links, and devices present on the network. The most relevant routing information involves various measures that are often obtained in an imprecise or inaccurate manner, thus suggesting that fuzzy reasoning is a natural method to employ in an improved routing scheme. The neural network is deemed as a suitable accompaniment because it maintains the ability to learn in dynamic situations. Once the neural network is initially designed, any alterations in the computer routing environment can easily be learned by this adaptive artificial intelligence method. The capability to learn and adapt is essential in today's rapidly growing and changing computer networks. These techniques, fuzzy reasoning and neural networks, when combined together provide a very effective routing algorithm for computer networks. Computer simulation is employed to prove the new fuzzy routing algorithm outperforms the Shortest Path First (SPF) algorithm in most computer network situations. The benefits increase as the computer network migrates from a stable network to a more variable one. The advantages of applying this fuzzy routing algorithm are apparent when considering the dynamic nature of modern computer networks. / Ph. D.

To achieve information superiority in a coalition environment the U. S. has to seamlessly integrate coalition members, both NATO and Non-NATO, into its command and control processes along all echelons of military operations. In a coalition environment, it is extremely challenging to fuse multinational information systems to achieve seamless integration. This thesis focuses on the security issues that are involved in establishing coalition network interoperability. The coalition environment is defined in terms of purpose, command structure, mission area, and control functions. Network and information protection are discussed in terms of minimizing the threats to information systems security. Coalition information system user requirements are defined and some of the security mechanisms required to meet those requirements are discussed. Current solutions to secure coalition network interoperability are surveyed, followed by conclusions, recommendations and areas for further study. / US Navy (USN) author

A thesis submitted to the Faculty of Engineering, University of the '\Vitwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy / THIS STUDY identifies and evaluates factors that affect call connections in the South African public data networks, modelling these factors to aid data network planning. The research shows the relationship between the economic rank of each region served and the data communication resources required for that region. Moreover, it shows the resources required between regions. THE THRUST of this thesis is that the volume of cans from a region can be estimated from its economic ...k and more than 75% olthe variation in the volume of calls between regions can be explained using the ranks of the originating and terminating regions. To prove this, records of more than four million calls are accumulated for all regions of the South African packet switched data network. An appropriate filtering and aggregation method is developed. EXISTING growth models including the gravity model are separately examined. Based on probability and dimensional arguments, the Bell System growth model is selected. It is revealed that the success of this model depends on one premise being satisfied: this model tacitly anti implicitly assumes that the originating and terminating calls are statistically independent. RETURNING to the data network, it is found that the call connections (after filtering and aggregation) display dependence of destination on origin. Reasons for the dependence are discovered. Multiple linear regression reveals the nature of this dependence. Surprisingly, distance is not a factor. The importance of regional ranks and an inter-regional indicator variable are also discovered. FINALL Y, call volume from a node is shown to be directly linked with the weighted Gross Regional and Industrial Product of the region. This quantity, in tum, is inversely related to the rank of the region. Call connections are then modelled to be equal to the call connections within the first tanked region divided by the product of the originating region's rank and the terminating region's rank. This simple and economical model explains 76% of the variations that occur in call connections. It has proved its use by being included in the data transfer services product-line report. / Andrew Chakane 2018

Message brokers are the backbone of modern publish subscribe messaging systems. These brokers can degrade or fail for a variety of reasons. This research specifically looks at the detection, prediction and mitigation of bottlenecks in brokers. The message-oriented-middleware framework here uses either a cluster of brokers on a Local Area Network (LAN) or a federation of brokers on a Wide Area Network (WAN) to route messages, facilitate multicasting and ameliorate demand surges and geographically related faults. Sensors have been constructed to monitor brokers and controllers to run the bottleneck detection algorithms. An overlay manager controls broker and topic pairing. Each topic is assigned a primary and secondary broker. When a failure is predicted, the overlay manager routes messages from the failing broker by switching topics to its secondary broker(s). The application for bottleneck forecasting is to allow us to pre-empt a broker failure and hence reroute messages to other brokers to increase resilience and reliability. The key contributions of this research are an abstract model of message-oriented-middleware broker based on the Apache Qpid message broker coupled with the use of analytical autoregressive exogenous (ARX) models that describes the broker behaviour during bottleneck conditions. The Apache Qpid message broker is a message broker that implements the Advanced Message Queuing Protocol (AMQP) for publish-subscribe messaging. ARX models are autoregressive models where the output depends on the previous output as well as external stimuli. These components are integrated to produce a generalised technique for calibrating broker performance and detection of bottlenecks in the broker. This research show how models were initially constructed using a complete range of input data. As bottlenecks occur only when the broker is heavily loaded, input data during idle periods can cause corruption to the model fit. Models were constructed with segmented input data, with each segment covering the range of one peak period. The segmented input allows the modelling of the broker behaviour only when it is experiencing a bottleneck. The result of this is a much-improved fit of the predictive models. The work here is compared against previous work using Markov-chains for creating predictive models. The results of both approaches are compared and reported.

Abstract not available

The dissertation addresses the communication issues of interconnecting the different government sectors LANs, and access to the global Internet. Network capacities are being purposely overengineered in today's commercial Internet. Any network provider, be it a commercial Internet Service Provider (ISP) or Information Technology Service department at government sector, company or university site, will design network bandwidth resources in such a way that there will be virtually no data loss, even during the worst possible network utilization scenario. Thus, the service delivered by today's end-to-end wide area Internet would be perfect if it wasn't for the inter-domain connections, such as Internet access link to the ISP, or peering points between ISPs. The thesis studies the performance of the network in Eritrea, displaying the problems of Local Area Networks (LANs) and Wide Area Networks (WAN) and suggesting initial solutions and investigating the performance of (WAN) through the measured traffic analysis between Asmara LAN and Massawa LAN, using queuing theory system (M/M/1 and M/M/2) solution. The dissertation also uses OPNET IT Guru simulation software program ·to study the performance of LAN and WLAN in Eritrea. The items studied include traffic, collision, packet loss, and queue delay. Finally in order to follow the current trends, we study the performance ofVOIP links in Eritrean WANs environment, with a focus on five different link capacities: 28 kbps, 33 kbps, 64 kbps, and 128 kbps for voice and 256/512 kbps for voice and data. Using the R value as a measure of mean opinion score (MOS), we determine that the 33 kbps link would be adequate for Eritrean WANs. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2006.

Thesis (M. App. Sc.)--Carleton University, 2005. / Includes bibliographical references (p. 179-183). Also available in electronic format on the Internet.

Report (M.S.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (M.B.A.)--University of Hong Kong, 1997. / Includes bibliographical references (leaf 72-73).