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This work approaches the little studied topic of compiler optimisations directed to network applications. It starts by investigating if there exist any fundamental differences between application domains that justify the development and tuning of domain-specific compiler optimisations. It shows an automated approach that is capable of identifying domain-specific workload characterisations and presenting them in a readily interpretable format based on decision trees. The generated workload profiles summarise key resource utilisation issues and enable compiler engineers to address the highlighted bottlenecks. By applying this methodology to data intensive network infrastructure application it shows that data organisation is the key obstacle to overcome in order to achieve high performance. It therefore proposes and evaluates three specialised data transformations (structure splitting, array regrouping, and software caching) against the industrial EEMBC networking benchmarks and real-world data sets. It also demonstrates on one hand that speedups of up to 2.62 can be achieved, but on the other that no single solution performs equally well across different network traffic scenarios. Hence, to address this issue, an adaptive software caching scheme for high frequency route lookup operations is introduced and its effectiveness evaluated one more time against EEMBC networking benchmarks and real-world data sets achieving speedups of up to 3.30 and 2.27. The results clearly demonstrate that adaptive data organisation schemes are necessary to ensure optimal performance under varying network loads. Finally this research addresses another issue introduced by data transformations such as array regrouping and software caching, i.e. the need for static analysis to allow efficient resource allocation. This thesis proposes a static code analyser that allows the automatic resource analysis of source code containing lists and tree structures. The tool applies a combination of amortised analysis and separation logic methodology to real code and is able to evaluate type and resource usage of existing data structures, which can be used to compute global resource consumption values for full data intensive network applications.

Broadband speeds, Internet literacy and digital technologies have been steadily evolving over the last decade. Broadband infrastructure has become a key asset in today’s society, enabling innovation, driving economic efficiency and stimulating cultural inclusion. However, populations living in remote and rural communities are unable to take advantage of these trends. Globally, a significant part of the world population is still deprived of basic access to the Internet. Broadband Wireless Access (BWA) networks are regarded as a viable solution for providing Internet access to populations living in rural regions. In recent years, Wireless Internet Service Providers (WISPs) and community organizations around the world proved that rural BWA networks can be an effective strategy and a profitable business. This research began by deploying a BWA network testbed, which also provides Internet access to several remote communities in the harsh environment of the Scottish Highlands and Islands. The experience of deploying and operating this network pointed out three unresolved research challenges that need to be addressed to ease the path towards widespread deployment of rural BWA networks, thereby bridging the rural-urban broadband divide. Below, our research contributions are outlined with respect to these challenges. Firstly, an effective planning paradigm for deploying BWA networks is proposed: incremental planning. Incremental planning allows to anticipate return of investment and to overcome the limited network infrastructure (e.g., backhaul fibre links) in rural areas. I have developed a software tool called IncrEase and underlying network planning algorithms to consider a varied set of operational metrics to guide the operator in identifying the regions that would benefit the most from a network upgrade, automatically suggesting the best long-term strategy to the network administrator. Second, we recognize that rural and community networks present additional issues for network management. As the Internet uplink is often the most expensive part of the operational expenses for such deployments, it is desirable to minimize overhead for network management. Also, unreliable connectivity between the network operation centre and the network being managed can render traditional centralized management approaches ineffective. Finally, the number of skilled personnel available to maintain such networks is limited. I have developed a distributed network management platform called Stix for BWA networks, to make it easy to manage such networks for rural/community deployments and WISPs alike while keeping the network management infrastructure scalable and flexible. Our approach is based on the notions of goal-oriented and in-network management: administrators graphically specify network management activities as workflows, which are run in the network on a distributed set of agents that cooperate in executing those workflows and storing management information. The Stix system was implemented on low-cost and small form-factor embedded boards and shown to have a low memory footprint. Third, the research focus moves to the problem of assessing broadband coverage and quality in a given geographic region. The outcome is BSense, a flexible framework that combines data provided by ISPs with measurements gathered by distributed software agents. The result is a census (presented as maps and tables) of the coverage and quality of broadband connections available in the region of interest. Such information can be exploited by ISPs to drive their growth, and by regulators and policy makers to get the true picture of broadband availability in the region and make informed decisions. In exchange for installing the multi-platform measurement software (that runs in the background) on their computers, users can get statistics about their Internet connection and those in their neighbourhood. Finally, the lessons learned through this research are summarised. The outcome is a set of suggestions about how the deployment and operation of rural BWA networks, including our own testbed, can be made more efficient by using the proper tools. The software systems presented in this thesis have been evaluated in lab settings and in real networks, and are available as open-source software.

This thesis extends HelenOS operating system in order to be IPv6 capa- ble. New IPv6 protocol implementation is on the same level as previous IPv4 protocol implementation. HelenOS networking stack now offers three modes of networking: IPv4-only, IPv6-only and dual stack mode. Dual stack mode enables usage of both protocols at once. The thesis describes previous state of HelenOS networking stack, analyzes differences between IPv4 and IPv6 protocols and gives reasons for single strategic decisions. In fine, it describes used implementation and debugging techniques, concludes results and compares HelenOS with other microkernel operating system from the IPv6-capability perspective. 1

Telcos are adapting their business to address the rapid changing technology landscape (Moodley and van Olst 2011). Telcos require a flexible architecture to allow seamless adaptation and to leverage these new technologies to gain a competitive advantage (Moodley and van Olst 2011). This research is focused on the transport stratum as an extension to the OSA/Parlay gateway. The proposed OSA/Parlay Network Architecture and Interface has been designed. The OSA/Parlay Network Interface is characterised by openness, simplicity, API based, QoS support and technology independence. The OSA/Parlay Network Architecture features simplicity, technology independence, QoS mechanisms; call admission control; intelligent routing and supporting both federation of telcos and interoperation of legacy technologies. The OSA/Parlay Network Architecture and Interface has been demonstrated over a Java based Distributed Processing Environment (DPE) using CORBA. These architectural concepts and principles are demonstrated in a simulated environment and illustrate the Next Generation Network architectural characteristics. The research contribution therefore achieves an open architecture allowing for 3rd party application developers while also ensuring that call and service requests are provisioned end-to-end with guaranteed application level QoS in the transport network. The OSA/Parlay Network Architecture and Network Interface is synthesised from existing architectural standards and provides the following benefits. It is an extension of the OSA/Parlay standard by including the OSA/Parlay Network Architecture and Network Interface realises the OSA/Parlay next generation network. Both the OSA/Parlay Network Interface and the Network Architecture is specified in a technology agnostic manner. This ensures that the architecture remains future proof as it is not reliant on any particular technology. The long sought after Application level QoS is integrated into the architecture. The periodic network state updates inform the central Connection Coordinator object of both topological network changes as well as current performance of the constituent parts of the network. Intelligent routing of connections is achieved by adapting the Dijkstra algorithm to compute the best path based on dynamic network performance and is tested against QoS requirements, while the call admission control decision naturally allows for load balancing of connection paths within the network. This QoS mechanism achieves the goal of guaranteed QoS for a call admitted into the network.

Vehicular ad hoc network (VANET) is a key component of intelligent transportation System (ITS). In VANETs, vehicles and roadside units exchange information for the purpose of navigation, safe driving, entertainment and so on. The high mobility of vehicles makes efficient and private communications in VANETs a big challenge. Improving the performance of information dissemination while protecting data privacy is studied in this research. Meet-Table based information dissemination method is first proposed, so as to improve the information dissemination, and to efficiently distribute information via utilizing roadside units, Cloud Computing, and Fog Computing. A clustering algorithm is proposed as well, to improve the stability for self-organized cluster-based dissemination in VANETs on highways. Then, fuzzy neural networks are used to improve the stability and security of routing protocols, AODV, and design a novel protocol, GSS-AODV. To further protect data privacy, a multi-antenna based information protection approach for vehicle-to-vehicle(V2V) communications is also proposed.

The past 20 years have seen the Internet evolve from a network connecting academics, to a critical part of our daily lives. The Internet now supports extremely popular services, such as online social networks and user generated content, in addition to critical services such as electronic medical records and power grid control. With so many users depending on the Internet, ensuring that data is delivered dependably is paramount. However, dependability of the Internet is threatened by the dual challenges of ensuring (1) data in transit cannot be intercepted or dropped by a malicious entity and (2) services are not impacted by unreliability of network components. This thesis takes an end-to-end approach and addresses these challenges at both the core and edge of the network. We make the following two contributions: A strategy for securing the Internet's routing system. First, we consider the challenge of improving security of interdomain routing. In the core of the network, a key challenge is enticing multiple competing organizations to agree on, and adopt, new protocols. To address this challenge we present our three-step strategy that creates economic incentives for deploying a secure routing protocol (S*BGP). The cornerstone of our strategy is S*BGP's impact on network traffic, which we harness to drive revenue-generating traffic toward ISPs that deploy S*BGP, thus creating incentives for deployment. Empirical study of data center network reliability. Second, we consider the dual challenge of improving network reliability in data centers hosting popular content. The scale at which these networks are deployed presents challenges to building reliable networks, however, since they are administered by a single organization, they also provide opportunity to innovate. We take a first step towards designing a more reliable network infrastructure by characterizing failures in a data center network comprised of tens of data centers and thousands of devices. Through dialogue with relevant stakeholders on the Internet (e.g., standardization bodies and large content providers), these contributions have resulted in real world impact. This impact has included the creation of an FCC working group, and improved root cause analysis in a large content provider network.