This thesis presents the analysis and experimental results for an evaluation of the performance and Quality of Service (QoL) levels of a virtual private network( QoL) levels of a Virtual Private Network (VPN) implementation of an IEEE 802.11b wireless infrastructure. The VPN tunnelling protocol considered for the above study is IP security (IPSec). The main focus of the research is to identify the major performance limitations and their underlying causes for such VPN implementations under study. The experimentation and data collection involved in the study spans over a number of platforms to suit a range of practical VPN implementations over a wireless medium. The collected data includes vital QoS and performance measures such as the application throughput, packet loss, jitter, and round-trip delay. Once the baseline measure is established, a series of experiments are conducted to analyse the behaviour of a single IPSec VPN operating over an IEEE 802.11b infrastructure, after which the experimentation is extended by investigating the trends of the performance metrics of a simultaneously multiple VPN setup. The overall results and analysis of the investigation concludes that the CPU processing power, payload data size, packet generation rate and the geographical distance are critical factors affecting the performance of such VPN tunnel implementations. Furthermore, it is believed that these results may give vital clues for enhancing and achieving optimal performance and QoS levels for VPN applications over WLANs / Master of Science (Hons.)

The Internet currently supports a best-effort connectivity service. There has been an increasing demand for the Internet to support Quality of Service (QoS) to satisfy stringent service requirements from many emerging networking applications and yet to utilize the network resources efficiently. However, it has been found that even with augmented QoS architecture, the Internet cannot achieve the desired QoS and furthermore, there are concerns about the scalability of any available QoS solutions. If the network is not provisioned adequately, the Internet is not capable to handle congestion condition. This is because the Internet is unaware of its internal network QoS states therefore it is not possible to provide QoS when the network state changes dynamically. This thesis addresses the following question: Is it possible to deliver the applications with QoS in the Internet fairly and efficiently while keeping scalability? In this dissertation we answer this question affirmatively by proposing an innovative service architecture: the Resource Discovery (RD) and Fair Intelligent Admission Control (FIAC) over scalable Internet. The main contributions of this dissertation are as follows: 1. To detect the network QoS state, we propose the Resource Discovery (RD) framework to provide network QoS state dynamically. The Resource Discovery (RD) adopts feedback loop mechanism to collect the network QoS state and reports to the Fair Intelligent Admission Control module, so that FIAC is capable to take resource control efficiently and fairly. 2. To facilitate network resource management and flow admission control, two scalable Fair Intelligent Admission Control architectures are designed and analyzed on two levels: per-class level and per-flow level. Per-class FIAC handles the aggregate admission control for certain pre-defined aggregate. Per-flow FIAC handles the flow admission control in terms of fairness within the class. 3. To further improve its scalability, the Edge-Aware Resource Discovery and Fair Intelligent Admission Control is proposed which does not need the core routers involvement. We devise and analyze implementation of the proposed solutions and demonstrate the effectiveness of the approach. For the Resource Discovery, two closed-loop feedback solutions are designed and investigated. The first one is a core-aware solution which is based on the direct QoS state information. To further improve its scalability, the edge-aware solution is designed where only the edges (not core)are involved in the feedback QoS state estimation. For admission control, FIAC module bridges the gap between 'external' traffic requirements and the 'internal' network ability. By utilizing the QoS state information from RD, FIAC intelligently allocate resources via per-class admission control and per-flow fairness control. We study the performance and robustness of RD-FIAC through extensive simulations. Our results show that RD can obtain the internal network QoS state and FIAC can adjust resource allocation efficiently and fairly.

A new multihop wavelength-division multiplexed (WDM) optical network designed for uniform traffic with two wavelengths per node that can give the maximum throughput and minimum delay is proposed. It is called a 'Simple Star' multihop optical network. This network has good characteristics in traffic balance and small average number of hops. Moreover, Simple Star can be used together with multiple star couplers to reduce the number of wavelength used. Furthermore, unlike most existing networks, this network does not impose an upper limit to the number of nodes. Another interesting pattern is Simple Star with Center Node (Simple Star CN) particularly for prime numbers of nodes. It can be shown that the average number of hops of Simple Star (normal plus CN) is in between those of Shufflenet and Kautz, but the throughput and delay are better. An associated network called Simple Star Shared Channel (Simple Star SC) for two transceivers per node is also presented and it can be used together with multiple star couplers to reduce the number of wavelengths. An example of a 16-node Simple Star SC shows that the number of wavelengths used can be 8 times less than that in the normal Simple Star network. The Shared Channel simulation model is based on the concept of CSMA/CD (Carrier Sense Multiple Access with Collision Detection).

The research recorded in this thesis tells the story of developing and implementing a user-centred intranet in the organisation where I work in a senior management position. My management support of the process led to adopting a networked model in our organisation, and also to my embracing the role of communications management.The organisation in which I work has a high rate of change and an entrepreneurial culture which is sometimes chaotic. This challenging environment was a good testing ground for the project, which sought to explore a number of propositions affirming the value of user-centred intranets.Developing and implementing the intranet encouraged collaboration amongst staff members. The intranet became a new channel of communication, which usefully enhanced the staff's ability to share and find out what was going on, who did what and how to contact them. My interventions as a manager, which occurred in parallel with the technological development of the intranet, led to spin-off organisational improvements such as an improved collaborative reporting system, the restructuring of the organisation manual files, and the establishment of a collaboratively-focussed full monthly staff meeting. Developing and implementing a user-centred intranet was a dynamic way to effect change in the organisation and orient it towards a networked organisational model, one which is communication rich, both collaborative and participative.The project was driven by my belief that a user-centred emphasis in intranet design is necessary in today's knowledge-based global economy, where there is a high rate of change. The networked organisational model should be embraced as a flexible model catering for change by promoting organic and dynamic networking within an organisation. This environment is communication-rich and collaborative, and a user-centred intranet is a communication channel well suited to support this model.A user-centred intranet should not be seen merely as an organisational artefact, but also as the a process of developing and implementing it will open up an organisation's culture, communication, and knowledge management in a participatory way. However, the degree that this will be achieved depends on a number of factors. For instance, the leaders of an organisation need to embrace a networked organisational model, encouraging and resourcing communication management for a culture of participation and collaboration.

Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed December 4, 2007) Includes bibliographical references (p. 74-80).

This thesis proposes new algorithms for restoration strategies that provision bandwidth guaranteed recovery for unicast and multicast connections. The primary focus is on online restoration strategies that sequentially do pre-planning of resource for each request using the current network resource state. Online restoration strategies do not require prior knowledge of all the requests like that of offline restoration strategies. Therefore, online restoration strategies are more suitable for on-demand and dynamic traffic engineering control. The proposed new algorithms are compared to known algorithms from literature. Most literature evaluates the performance of the algorithms with two metrics only: total bandwidth requirement and the number of requests accepted in the network. This thesis evaluates the algorithms in one additional dimension: the computational time. This is an important criterion when response times for establishing new connections are stringent. Each algorithm makes trade-off between computational complexity, bandwidth efficiency, and number of accepted requests. Results show that the proposed algorithms provide alternative trade-offs between the three performance metrics when compared to other existing algorithms. The alternatives provide more choice for the network providers and the best algorithm to use depends on the network's requirements. The restoration strategies used for unicast and multicast connections in this thesis are very compatible thus it is possible to integrate the restoration strategies into a single system where they share the same backup resources. Results from simulations show that using an integrated restoration model has significant benefits, which includes lower backup bandwidth requirement than the separate restoration model.

This thesis proposes new algorithms for restoration strategies that provision bandwidth guaranteed recovery for unicast and multicast connections. The primary focus is on online restoration strategies that sequentially do pre-planning of resource for each request using the current network resource state. Online restoration strategies do not require prior knowledge of all the requests like that of offline restoration strategies. Therefore, online restoration strategies are more suitable for on-demand and dynamic traffic engineering control. The proposed new algorithms are compared to known algorithms from literature. Most literature evaluates the performance of the algorithms with two metrics only: total bandwidth requirement and the number of requests accepted in the network. This thesis evaluates the algorithms in one additional dimension: the computational time. This is an important criterion when response times for establishing new connections are stringent. Each algorithm makes trade-off between computational complexity, bandwidth efficiency, and number of accepted requests. Results show that the proposed algorithms provide alternative trade-offs between the three performance metrics when compared to other existing algorithms. The alternatives provide more choice for the network providers and the best algorithm to use depends on the network's requirements. The restoration strategies used for unicast and multicast connections in this thesis are very compatible thus it is possible to integrate the restoration strategies into a single system where they share the same backup resources. Results from simulations show that using an integrated restoration model has significant benefits, which includes lower backup bandwidth requirement than the separate restoration model.

MANETs are known to be useful in situations where mobile nodes need to communicate and coordinate in dynamic environments with no access to fixed network infrastructure. However, connectivity problems can occur when sub-groups within a MANET move out of communication range from one another. The increasingly prolific use of UAVs in military and civilian contexts suggests that UAVs may be very useful for facilitating connectivity between otherwise disconnected mobile nodes. Network Centric Warfare (NCW) theory makes heavy use of MANETs, and UAVs also fit well into the NCW theory; this paper describes the work involved in integrating network enabled UAVs into a previously-developed simulation of ground troop mobility called UMOMM. Specifically, we created a simple decision model for constrained, constant-radius UAV movements, and developed a target-based method by which UAVs can distribute themselves in order to improve the connectivity of the ground members of the MANET. / Graduation date: 2012

An important objective of tactical ad hoc networks is to deliver threat information from sensors to shooters efficiently and quickly. The information sent to a particular shooter should contain warnings about threats that are within some distance and/or within some time of the shooter's current location. In this thesis we develop a novel multicast model that distributes this form of threat information in a message efficient manner. In addition, information about allied force can also be distributed in a similar way. We present results from extensive simulations that demonstrate the efficiency of our protocol and discuss the scalability of this model to larger networks. / Graduation date: 2001

The most important part of parallel computation is communication. Except in the most embarassingly parallel examples, processors cannot work cooperatively to solve a problem unless they can communicate. One way to solve the problem of communication is to use an interconnection network. Processors are located at nodes of the network, which are joined by communication channels. Desirable aspects of an interconnection network include low maximum and average routing distances (as measured in the number of communication channels crossed), a large number of processors, and low number of communication channels per processor. A number of published networks are created from the hypercube by rearranging the hypercube's communication links in a systematic way [23] [28] [30] [33] [50]. These networks maintain the same number of processors, communication links, and links per processor as the hypercube, but have dramatically smaller maximum and average routing distances. This thesis derives one formal mathematical description for this family of networks. This formal description is used to derive graph-theoretic properties of existing networks, and to design new networks. The description is also used to design generalized routing and other communications algorithms for these networks, and to show that these networks can embed and simulate other standard networks, for instance, ring and mesh networks. A network simulator is used to model the dynamic behavior of this family of networks under both store-and-forward and wormhole routing strategies for message-passing. The simulation results are used to study and compare the networks' behavior under various message-passing loads, and to determine what properties are desirable in a network that exists in this model. / Graduation date: 1995