A flexible receiver-driven cache replacement scheme for continuous media objects in best-effort networks

In this paper, we investigate the potential of caching to improve quality of reception (QoR) in the context of continuous media applications over best-effort networks. Specifically, we investigate the influence of parameters such as loss rate, jitter, delay and area in determining a proxy\u27s cache contents. We propose the use of a flexible cost function in caching algorithms and develop a framework for benchmarking continuous media caching algorithms. The cost function incorporates parameters in which, an administrator and or a client can tune to influence a proxy\u27s cache. Traditional caching systems typically base decisions around static schemes that do not take into account the interest of their receiver pool. Based on the flexible cost function, an improvised Greedy Dual (GD) algorithm called GD-multi has been developed for layered multiresolution multimedia streams. The effectiveness of the proposed scheme is evaluated by simulation-based performance studies. Performance of several caching schemes are evaluated and compared with those of the proposed scheme. Our empirical results indicate GD-multi performs well despite employing a generalized caching policy

Naming and discovery in networks : architecture and economics

In less than three decades, the Internet was transformed from a research network available to the academic community into an international communication infrastructure. Despite its tremendous success, there is a growing consensus in the research community that the Internet has architectural limitations that need to be addressed in a effort to design a future Internet. Among the main technical limitations are the lack of mobility support, and the lack of security and trust. The Internet, and particularly TCP/IP, identifies endpoints using a location/routing identifier, the IP address. Coupling the endpoint identifier to the location identifier hinders mobility and poorly identifies the actual endpoint. On the other hand, the lack of security has been attributed to limitations in both the network and the endpoint. Authentication for example is one of the main concerns in the architecture and is hard to implement partly due to lack of identity support. The general problem that this dissertation is concerned with is that of designing a future Internet. Towards this end, we focus on two specific sub-problems. The first problem is the lack of a framework for thinking about architectures and their design implications. It was obvious after surveying the literature that the majority of the architectural work remains idiosyncratic and descriptions of network architectures are mostly idiomatic. This has led to the overloading of architectural terms, and to the emergence of a large body of network architecture proposals with no clear understanding of their cross similarities, compatibility points, their unique properties, and architectural performance and soundness. On the other hand, the second problem concerns the limitations of traditional naming and discovery schemes in terms of service differentiation and economic incentives. One of the recurring themes in the community is the need to separate an entity\u27s identifier from its locator to enhance mobility and security. Separation of identifier and locator is a widely accepted design principle for a future Internet. Separation however requires a process to translate from the identifier to the locator when discovering a network path to some identified entity. We refer to this process as identifier-based discovery, or simply discovery, and we recognize two limitations that are inherent in the design of traditional discovery schemes. The first limitation is the homogeneity of the service where all entities are assumed to have the same discovery performance requirements. The second limitation is the inherent incentive mismatch as it relates to sharing the cost of discovery. This dissertation addresses both subproblems, the architectural framework as well as the naming and discovery limitations

Doctor of Philosophy

dissertationNetwork emulation has become an indispensable tool for the conduct of research in networking and distributed systems. It offers more realism than simulation and more control and repeatability than experimentation on a live network. However, emulation testbeds face a number of challenges, most prominently realism and scale. Because emulation allows the creation of arbitrary networks exhibiting a wide range of conditions, there is no guarantee that emulated topologies reflect real networks; the burden of selecting parameters to create a realistic environment is on the experimenter. While there are a number of techniques for measuring the end-to-end properties of real networks, directly importing such properties into an emulation has been a challenge. Similarly, while there exist numerous models for creating realistic network topologies, the lack of addresses on these generated topologies has been a barrier to using them in emulators. Once an experimenter obtains a suitable topology, that topology must be mapped onto the physical resources of the testbed so that it can be instantiated. A number of restrictions make this an interesting problem: testbeds typically have heterogeneous hardware, scarce resources which must be conserved, and bottlenecks that must not be overused. User requests for particular types of nodes or links must also be met. In light of these constraints, the network testbed mapping problem is NP-hard. Though the complexity of the problem increases rapidly with the size of the experimenter's topology and the size of the physical network, the runtime of the mapper must not; long mapping times can hinder the usability of the testbed. This dissertation makes three contributions towards improving realism and scale in emulation testbeds. First, it meets the need for realistic network conditions by creating Flexlab, a hybrid environment that couples an emulation testbed with a live-network testbed, inheriting strengths from each. Second, it attends to the need for realistic topologies by presenting a set of algorithms for automatically annotating generated topologies with realistic IP addresses. Third, it presents a mapper, assign, that is capable of assigning experimenters' requested topologies to testbeds' physical resources in a manner that scales well enough to handle large environments

Overlay auxiliary routing: achieving near minimum delay routing solutions for overlay networks.

Zhang Li.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.Includes bibliographical references (leaves 71-74).Abstracts in English and Chinese.Abstract --- p.ii摘要 --- p.ivAcknowledgments --- p.vContents --- p.viChapter Chapter 1 --- Introduction --- p.1Chapter Chapter 2 --- Internet Routing and Performance Studies --- p.5Chapter 2.1 --- Border Gateway Protocol Version 4 (BGP4) --- p.5Chapter 2.2 --- Internet Performance Studies --- p.6Chapter 2.3 --- Improve Routing Performance --- p.8Chapter 2.3.1 --- Traffic Engineering --- p.8Chapter 2.3.2 --- Network-layer Techniques --- p.9Chapter 2.3.3 --- Minimum Delay Routing --- p.11Chapter Chapter 3 --- Overlay-based Techniques --- p.15Chapter 3.1 --- Content Distribution Network --- p.16Chapter 3.2 --- Relative Overlay Techniques --- p.16Chapter Chapter 4 --- Overlay Minimum Delay Routing --- p.19Chapter 4.1 --- Minimum Delay Routing in Overlay Network --- p.21Chapter 4.1.1 --- Problem Formulation --- p.21Chapter 4.1.2 --- Necessary and Sufficient Conditions for Distributed Computing --- p.25Chapter 4.1.3 --- Optimal Overlay Auxiliary Routing (00AR) Algorithm --- p.29Chapter 4.2 --- Performance Comparing with Optimal IP routing --- p.31Chapter Chapter 5 --- Sub-Optimal Overlay Auxiliary Routing Algorithm --- p.39Chapter 5.1 --- Approximation Conditions to Optimal Overlay Routing --- p.40Chapter 5.2 --- SOAR algorithm Overview --- p.44Chapter 5.3 --- Distributing Traffic over Multiple Paths --- p.49Chapter 5.3.1 --- Adaptive load Adjustment --- p.50Chapter 5.3.2 --- Per-flow Routing Control --- p.53Chapter 5.4 --- Discussion on Marginal Delay of an OAR Link --- p.55Chapter Chapter 6 --- Performance Evaluation of Sub-Optimal Overlay Auxiliary Routing --- p.57Chapter 6.1 --- Experiment Method Description --- p.57Chapter 6.2 --- Comparison of overall delay --- p.61Chapter 6.3 --- Effect of the Routing update interval parameters xx and yy --- p.64Chapter 6.4 --- Comparison of packet loss rate --- p.66Chapter 6.5 --- Comparison of potential maximum data transmission rate --- p.68Chapter 6.6 --- Stability of the OAR load-balancing heuristics algorithm --- p.69References --- p.71Appendix --- p.7

Secure Multi-Path Selection with Optimal Controller Placement Using Hybrid Software-Defined Networks with Optimization Algorithm

The Internet's growth in popularity requires computer networks for both agility and resilience. Recently, unable to satisfy the computer needs for traditional networking systems. Software Defined Networking (SDN) is known as a paradigm shift in the networking industry. Many organizations are used SDN due to their efficiency of transmission. Striking the right balance between SDN and legacy switching capabilities will enable successful network scenarios in architecture networks. Therefore, this object grand scenario for a hybrid network where the external perimeter transport device is replaced with an SDN device in the service provider network. With the moving away from older networks to SDN, hybrid SDN includes both legacy and SDN switches. Existing models of SDN have limitations such as overfitting, local optimal trapping, and poor path selection efficiency. This paper proposed a Deep Kronecker Neural Network (DKNN) to improve its efficiency with a moderate optimization method for multipath selection in SDN. Dynamic resource scheduling is used for the reward function the learning performance is improved by the deep reinforcement learning (DRL) technique. The controller for centralised SDN acts as a network brain in the control plane. Among the most important duties network is selected for the best SDN controller. It is vulnerable to invasions and the controller becomes a network bottleneck. This study presents an intrusion detection system (IDS) based on the SDN model that runs as an application module within the controller. Therefore, this study suggested the feature extraction and classification of contractive auto-encoder with a triple attention-based classifier. Additionally, this study leveraged the best performing SDN controllers on which many other SDN controllers are based on OpenDayLight (ODL) provides an open northbound API and supports multiple southbound protocols. Therefore, one of the main issues in the multi-controller placement problem (CPP) that addresses needed in the setting of SDN specifically when different aspects in interruption, ability, authenticity and load distribution are being considered. Introducing the scenario concept, CPP is formulated as a robust optimization problem that considers changes in network status due to power outages, controller’s capacity, load fluctuations and changes in switches demand. Therefore, to improve network performance, it is planned to improve the optimal amount of controller placements by simulated annealing using different topologies the modified Dragonfly optimization algorithm (MDOA)

Quality-of-service management in IP networks

Quality of Service (QoS) in Internet Protocol (IF) Networks has been the subject of active research over the past two decades. Integrated Services (IntServ) and Differentiated Services (DiffServ) QoS architectures have emerged as proposed standards for resource allocation in IF Networks. These two QoS architectures support the need for multiple traffic queuing systems to allow for resource partitioning for heterogeneous applications making use of the networks. There have been a number of specifications or proposals for the number of traffic queuing classes (Class of Service (CoS)) that will support integrated services in IF Networks, but none has provided verification in the form of analytical or empirical investigation to prove that its specification or proposal will be optimum. Despite the existence of the two standard QoS architectures and the large volume of research work that has been carried out on IF QoS, its deployment still remains elusive in the Internet. This is not unconnected with the complexities associated with some aspects of the standard QoS architectures. [Continues.

Structure and dynamics of complex systems

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.A family of navigation algorithms for packet transport in complex networks is introduced. These algorithms use deterministic and probabilistic rules which depend, in different ways, on the degree of the node, packet flow and the temporal properties of packet delivery and distribution. On scale-free networks all our algorithms can handle a larger load than the random walk algorithm. I examined the fluctuation properties of packet traffic on scale-free networks and random graphs using random diffusion and a locally navigated diffusive motion with preferred edges. I found that preferential behaviour in either the topology or in the dynamics leads to the scaling of fluctuations of the number of packets passing nodes and the number of packets flowing along edges, respectively. I showed that the absence of any preference results in the absence of scaling. Broad distributions of the return times at nodes and edges illustrate that the basis of the observed scaling is the cooperative behaviour between groups of nodes or edges. I presented an empirical study of the networks created by users within internet news groups and forums and showed that they organise themselves into scale-free trees. The structure of these trees depends on the topic under discussion; specialist topics have trees with a short shallow structure whereas more universal topics are discussed widely and have a deeper tree structure. The correlation function of activity shows long range correlations connected with the users' daily routines. I presented an analysis of empirical data on the arrival and discharge times at a UK Accident and Emergency (A&E) department. I found that discharges rates vary with the workload and that the distribution of the length of stay has a fat tail. A sand pile model is introduced to show that the A&E department is a driven self-organised system. In my model I used a variable input space to mimic the queuing discipline related to different types of patients presenting to the department

Quality of service routing for real-time traffic

Imperial Users onl

A cooperative communication protocol for wireless ad-hoc networks

Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 59-61).This thesis presents the design and implementation of a communication protocol that utilizes local cooperation among nodes to efficiently transfer data. Multi-hop routing in ad-hoc wireless networks realizes some scalability benefits over direct transmission by utilizing cooperation in the network layer, where all nodes act as routers to relay messages. Cooperative transmission takes this idea a step further, moving cooperation to the link layer, where nodes actually broadcast signals simultaneously to increase signal strength. Using network topology information derived from propagation delay measurement, nodes dynamically establish and update membership in rebroadcasting cells. Rebroadcast cells use constructively interfering modulation schemes to broadcast radio signals together, directing an amplified signal toward the intended recipient. This results in a link-layer routing system well suited to real-time data streaming in mobile, ad-hoc, wireless networks.by Jeremy I. Silber.M.Eng.and S.B