The increasing demand for low-latency, high-bandwidth connectivity has introduced novel challenges to delivering strong resilience guarantees in production network environments. Closed hardware platforms, known as middleboxes, that lack visibility and support for state retention remain a key challenge for continuous service delivery during network failures. These middleboxes rarely employ recovery mechanisms of their own, inspiring renewed interest in the field of NFV in recent years due to this gap within the industry. The increasing availability of VNF capabilities in modern infrastructures offers an opportunity to exploit the flexibility of software and use hybrid architectures to improve resilience. Katoptron is a high-availability service that propagates state between unmodified hardware middleboxes and backup PNF or VNF appliances. The platform utilises targeted packet mirroring to allow network devices to organically construct equivalent state and thus allow an easy transition between hardware and software. To demonstrate its viability, we have evaluated Katoptron against a wide range of common hardware middlebox use cases built using multiple open-source packet processing frameworks. Results show upwards of 90% matching state with no observable delay to normal traffic or impact on its functionality.

This paper presents the development of a hybrid octoplane model and an LPV-based SMC FTC to deal with actuator faults/failures. The paper focuses on the challenging transition mode (the mode between vertical take-off/landing or hover and cruise) and exploits the additional redundancy in the octoplane's actuators for FTC. The proposed scheme is LPV-based and designed to handle large variations in speed during the transition mode from low-speed take-off to high-speed cruise. Simulation results obtained from the nonlinear model demonstrate that the proposed scheme provides good tracking performance in all fault-free as well as fault/failure cases, highlighting the efficacy of the scheme.

Resilience in networks has often relied on high availability to ensure minimal disruption to end users when faults occur, but this has grown difficult for retaining state with the growing popularity of hardware middleboxes – blackbox hardware network functions that have served as an important part of network design in recent years. There is potential room for the introduction of Network Function Virtualisation (NFV) in the field of resilience in connection with middlebox usage. Rather than relying on overprovisioning, we propose Middlebox Minion (MiMi) VNF, a system design that can be inserted around inaccessible hardware. This recreates state in accordance with the middlebox function, using NFV to establish stateful failover mechanisms without the need to replace existing hardware. The experiment we present is a failover analogy examining the importance of state retention and the complexities involved with inaccessible hardware. Results suggest a promising improvement of connection quality and up to 60% lower loss when state can be preserved across failover instances, as well as potential for further exploration of the topic area.

HTTP adaptive video streaming matches video quality to the capacity of a changing context. A variety of schemes that rely on buffer state dynamics for video rate selection have been proposed. However, these schemes are predominantly based on heuristics, and appropriate models describing the relationship between video rate and buffer levels have not received sufficient attention. In this paper, we present a QoE-aware video rate evolution model based on buffer state changes. The scheme is evaluated within a real-world Internet environment. The results of an extensive evaluation show an improvement in the stability, average video rate and system utilisation, while at the same time a reduction in the start-up delay and convergence time is achieved by the modified players.

The Internet is often thought to be a model of resilience, due to a decentralised, organically-grown architecture. This paper puts this perception into perspective through the results of a security analysis of the Border Gateway Protocol (BGP) routing infrastructure. BGP is a fundamental Internet protocol and its intrinsic fragilities have been highlighted extensively in the literature. A seldom studied aspect is how robust the BGP infrastructure actually is as a result of nearly three decades of perpetual growth. Although global black-outs seem unlikely, local security events raise growing concerns on the robustness of the backbone. In order to better protect this critical infrastructure, it is crucial to understand its topology in the context of the weaknesses of BGP and to identify possible security scenarios. Firstly, we establish a comprehensive threat model that classifies main attack vectors, including but non limited to BGP vulnerabilities. We then construct maps of the European BGP backbone based on publicly available routing data. We analyse the topology of the backbone and establish several disruption scenarios that highlight the possible consequences of different types of attacks, for different attack capabilities. We also discuss existing mitigation and recovery strategies, and we propose improvements to enhance the robustness and resilience of the backbone. To our knowledge, this study is the first to combine a comprehensive threat analysis of BGP infrastructures withadvanced network topology considerations. We find that the BGP infrastructure is at higher risk than already understood, due to topologies that remain vulnerable to certain targeted attacks as a result of organic deployment over the years. Significant parts of the system are still uncharted territory, which warrants further investigation in this direction.

Adaptive bitrate selection adjusts the quality of HTTP streaming video to a changing context. A number of different schemes have been proposed that use buffer state in the selection of the appropriate video rate. However, models describing the relationship between video quality levels and buffer occupancy are mostly based on heuristics, which often results in unstable and/or suboptimal quality. In this paper, we present a QoE-aware video rate evolution model based on buffer state changes. The scheme is evaluated within a real world Internet environment, where it is shown to improve the stability of the video rate. Up to 27% gain in average video rate can be achieved compared to the baseline ABR. The average throughput utilisation at a steady-state reaches 100% in some of the investigated scenarios.

For all Locator Identity Split protocols to work, a mapping infrastructure is required to maintain the binding between the Locators and Identifiers. However, the mapping infrastructure naturally becomes one of the main scalability concerns when there are a large number of mobile nodes to support. This paper implements and evaluates a tiered architecture in which the mapping infrastructure is divided into a core mapper and an internal mapper such that it can support a large number of mobile nodes and providing up-to-date mapping records. The GSE/8+8 rewriting approach is used to underpin the routing within the tiered architecture. The core mapper uses a Chord DHT and the internal mapper is a hierarchy of routers with rewriting capability. The tiered architecture is simulated in OMNeT++. The simulation results show the tiered architecture is a viable solution for scaling the mapping infrastructure to support a large number of mobile nodes.

Multi-homing has become ubiquitous in the mobile domain. Despite this, mobile devices are not yet capable of fully realizing the potential of the increasing variety and availability of network resources. Multipath-TCP (MPTCP) is one of the most prominent technologies for multi-homed mobile devices, that is able to effectively tackle both resource pooling and mobility. Despite the success of MPTCP we believe that the implementation can be enhanced for the mobile domain, by increasing the granularity of control a device has over how its network interfaces are used. In this paper we present and evaluate MPTCP - Context Aware (MPTCP-CA), which introduces a policy oriented approach to the management and control of MPTCP connections. Our evaluation demonstrates three use cases that leverage context awareness to improve the utilization of multiple network interfaces with respect to the users requirements.

IP mobility ensures network reachability and session continuity while IPv6 networks are on the move. In the Network Mobility (NEMO) model, the potential for NEMO Mobile Routers (MRs) to interconnect and extend Internet connectivity allows the formation Nested NEMO networks. With MANEMO, nested MRs can be efficiently interconnected in a tree-based structure with Internet access being maintained via a designated Gateway. However, this only supports single-homed Internet connectivity. With the span of wireless access technologies and the popularity of multi-interfaced devices, multihoming support in this scenario becomes critical. A Nested Mobile Network with heterogeneous available Internet access options would allow better overall network performance and optimal utilisation of available resources. In this paper, we present the Multihomed Mobile Network Architecture (MMNA), a comprehensive multihomed mobility solution. It provides a multihoming management mechanism for Gateway Discovery and Selection on top of a multihomed mobility model integrating different mobility and multihoming protocols. It enables a complex nested multihomed topology to be established with multiple gateways supporting heterogeneous Internet access. The results demonstrate that the proposed solution achieves better overall throughput, load sharing, and link failure recovery.

Multihoming has become increasingly common, especially in the mobile domain. This enables co-located devices to form networks on demand. These networks can then be used to share and extend Internet connectivity. As multiple heterogeneous links are available on each device, additional points of Internet access are exposed within the network, typically they are left unused. In this paper we propose and evaluate a technique which enables multipath communications to take advantage of these additional links, by doing so we increase bandwidth, resilience and therefore the quality of service and experience. This is achieved by disseminating multihomed information into the network, with the intention of building a complete topological view at each host. Consequently, this enables intelligent link selection per application, as well as facilitating multipath protocols to use any available network resource.

The European market for roaming services has historically experienced poor or no competition and, when competition has occurred, prices have been largely resistant to its downward pressure [8]. The root cause of this failure lies in the technical limitations of the existing roaming architecture. An architecture able to remove these limitations should allow the contractual mobility of roaming users: users should be able to select their access provider automatically, on a per-session basis and on one-to-one contractual basis. In this paper, we study the extent to which, by removing these constraints, the enablement of contractual mobility influences user and provider behaviour, creating an improved market outcome. To this end, we develop a model of the relationships between contractual mobility as a design choice for roaming, the behaviour of market players in response to that choice, and market outcomes. We then study its evolution over time as design choices and settings change in different experiment scenarios. Our results show that enabling contractual mobility - either as a commercial choice by providers or mandated by the regulator - creates similar incentives for both potential users and new providers to enter the market, while decreasing switching barriers. These encouraging, albeit seminal results could form the basis for the development of a techno-economic model of roaming aimed to reduce the uncertainty as to the timeliness and efficacy of national regulators' policies.

Grid computing has been widely adopted for intensive high performance computing. Since grid resources are distributed over complex large-scale infrastructures, understanding grid site data traffic behaviour is important for efficient resource utilisation, performance optimisation, and the design of future grid sites as well as traffic-aware grid applications. In this paper, we study and analyse the traffic generated at a grid site in the Large Hadron Collider (LHC) Computing Grid (LCG). We find that most of the generated traffic is TCP-based and that a small set of grid applications generate significant amounts of the data. Upon analysing the different traffic metrics, we also find that the traffic exhibits long-range dependence and self-similarity. We also investigate packet-level metrics such as throughput, packet rate, round trip time (RTT) and packet loss. Our study establishes that these metrics can be well represented by Gaussian mixture models. The findings we present in this paper will enable accurate grid site traffic monitoring and potentially on-the-fly traffic modelling and prediction. It will also lead to a better understanding of grid site's traffic behaviour and contribute to more efficient grid site planning, traffic management, data transmission protocol optimisation, and data-aware grid application design.

The current Internet architecture is facing serious scaling problems notably in its routing and addressing system. Also due to the overloaded semantic of the IP address, the current Internet architecture cannot inherently support mobility and multihoming. To solve these problems, different Locator Identity Spilt solutions have been proposed. However most of these solutions tend to focus only on part of the problem space, and usually place mobility aside. For all Locator Identity Split protocols to work a Mapping Infrastructure is required. We believe that this Mapping Infrastructure would not scale efficiently with a high number of mobile nodes and would contribute to a large amount of packet loss while mobile nodes are roaming. This paper proposes a tiered architecture which divides the Mapping Infrastructure into a core mapper and an internal mapper. This separation allows the Mapping Infrastructure to scale in a highly mobile scenario.

Aiding the efficient collaboration and coordination of rescue teams is a difficult task especially in a mountainous region. Challenges emerge from quickly alerting and debriefing rescuers, to deploying them effectively, and also coordinating and monitoring them in the rural search domain. Knowing the exact location of the rescuers and vehicles involved in a mountain search and rescue mission is a key element for the successful progress of the mission and aids the mission coordinator, who usually stays at the headquarters, to take fast and informed decisions. In this paper we present the devised Location Awareness Rescue System that targets the aforementioned challenges, and provides location information and updates of the rescuers in a real time manner as they are deployed in the rescue domain overlaid onto interactive maps. The results from our tests show that our system is a proficient presence management solution that can provide precise location information by recovering from any periodic or total connectivity loss, and also improve and support mountain rescue teams leading to more effective and successful missions.

The aim of this article is to introduce an approach to providing connectivity on public transport connecting to the wider Internet via heterogeneous networks and prioritizing traffic according to service classes. We present a packet prioritization for each service class: premium, intermediate and default. A railway scenario is considered as our case study to evaluate the prioritization mechanisms. Experiments using the NS-2 simulator are to implement and evaluate the model. Results are presented to show the effectiveness of the model for network mobility in heterogeneous environments.

Grids offer the potential to carry out difficult computing tasks and achieve superior aggregate performance. However, grids are highly complex systems. They consist of heterogeneous resources on disparate hosts from various virtual organizations interconnected via a mixture of communication standards. Monitoring grid resources allows grid schedulers to adapt to changes in the status of these remote resources and the network paths between them. This is crucial to ensuring optimum performance. In this paper we introduce a distributed solution, called GridMAP, to collect network and end-host resource measurements, analyze their performance and feed these statistics and predictions back to schedulers. At this stage, we present our implementation of a passive TCP-SYN-based technique to provide GridMAP with round trip time and throughput measurements and we evaluate our approach against ping and iperf.

Mobile ad hoc network (MANET) routing protocols have been the focus of an accomplished research effort for many years within the networking community and now the results of this effort are beginning to show. With protocol development maturing (and now typically concentrating on a smaller number of standardised routing protocols), increasing numbers of deployment successes are materialising. However, despite these successes and the relative stability of the protocol implementations, seamlessly incorporating MANETs into the Internet still presents many challenges that have hindered their deployment in important mobile scenarios. In this paper we discuss the inherent properties that have affected the adoption of MANET solutions and present an innovative new protocol which has been designed to comprehensively address these challenges. Using performance results acquired from our experimental testbed, we demonstrate how our approach can be used to produce MANET solutions that are highly suited to use in synergy with the current Internet architecture. Our protocol is based on the concept of integrating MANET routing protocols with network mobility (NEMO) technologies to produce what is termed a MANEMO solution. This has meant that by utilising the properties of both of these technologies we have been able to realise a solution that provides mobile networks with the efficient localised communication and robustness of MANETs, as well as the global reachability and the ability to provide structured AAA that a NEMO approach can support.

The NEMO basic support protocol is a home agent based technique (derived from mobile IPv6) that permits the mobility of a network of IPv6 devices to be supported through the use of a dedicated mobile router. This NEMO mobile router accepts connections from IPv6 nodes and transparently manages any IP mobility on their behalf, which means that as well as individual hosts, a NEMO mobile router can also accept connections from other NEMO mobile networks. When this occurs, the inter-connected NEMO mobile networks form a highly inefficient topology known as a nested NEMO network. In this paper we describe this concept and examine the properties of nested NEMO networks. In particular we highlight how their communication patterns differ from typical mobile ad hoc networks (MANET) and present example scenarios which demonstrate their potential application domain. We present the unified MANEMO architecture (UMA), a solution which has been developed in order to efficiently support these nested NEMO scenarios. Through varying experimental testbed configurations, we provide an evaluation of the protocols performance and demonstrate how our approach is able to be deployed over the current Internet architecture without requiring any augmentation to access networks or the core Internet infrastructure.

This paper presents an observer based robust sensor fault reconstruction scheme. A popular observer based robust fault detection method is eigenstructure assignment; where the observer has certain eigenvectors, resulting in the fault detection scheme being decoupled from disturbances. This paper firstly investigates the existence conditions for the right eigenvector assignment method. Then an alternative scheme using reduced order observers is presented, with existence conditions that are less restrictive than that of right eigenvector assignment, whilst still being decoupled from disturbances. Following that, it proposes a design method for the observer using linear matrix inequalities. A design example validates the work in this paper; where the fault reconstruction scheme is totally decoupled from any disturbances

Video-based media spaces are designed to support casual interaction between intimate collaborators. Yet transmitting video is fraught with privacy concerns. Some researchers suggest that the video stream be filtered to mask out potentially sensitive information. While a variety of filtering techniques exist, they have not been evaluated for how well they safeguard privacy.

The ReTINA project (ACTS AC048) is an industrial collaboration to explore the use of CORBA for the support of real-time multimedia services, from the point of view of network control and from the point of view of middleware services. This paper covers CORBA for network control, and CORBA extensions towards a DPE framework for flexible binding and real-time support.