Evariste Logota

Advanced multicast class-based bandwidth over-provisioning

Dynamic bandwidth aggregate over-provisioning has been proposed to provide differentiated services with scalable Quality of Service (QoS) control. Previous research showed that efficient over-reservation control allows minimizing QoS control overhead with reduced waste of bandwidth and blocking probability. However, existing over-reservation centric solutions are still inefficient in the face of network dynamics, as they are not able to accommodate the dynamic service demands, thus failing to optimize the bandwidth usage. This paper proposes a new Advanced Class-based resource Over-Reservation (ACOR) solution for multicast sessions, which seeks increased network resources utilization while minimizing QoS control overhead. More specifically, ACOR is able to dynamically update the share of bandwidth between different classes of service, providing improved results with less complexity than current solutions. Our analytical and simulation results prove the cost-effective and scalable QoS control capabilities of ACOR in decentralized networks with multiple distributed ingress routers coordinating the QoS control.

A New Strategy for Efficient Decentralized Network Control

The limited scope of Internet architecture forced network providers implementing centralized mechanisms (QoS, group communication, mobility, etc) to support attractive value added sessions. Besides ease to manage, performance aspects of such mechanisms, mainly in terms of scalability, robustness and availability, are shortcoming. In this sense, decentralization is promising, since complex networking operations may be provided throughout the nodes, increasing the network performance. However, current distributed solutions implement their own strategies for decentralization (e.g. synchronization, resilience, etc.), which contributes to increase Internets complexity and damage overall performance. This paper introduces a cost-effective strategy for scalable decentralization of control operations in current Internet, called Self-Organizing Multiple Edge Nodes (SOMEN) mechanism. SOMEN enables multiple distributed network Control Decision Points -CDPs- (e.g. network borders) to jointly exploit control data inside a network with low signaling load. The effectiveness of SOMEN was proved through analytical modeling and simulation, which demonstrated significant minimization of control overhead.

COR: An efficient Class-based resource Over-pRovisioning mechanism for future networks

Recent research efforts claim that dynamic per-class network resource over-provisioning is promising, since aggregated over-reservations allow to significantly reduce state, processing and signaling overheads. However, over-reservation must be carefully controlled to prevent waste of resources, which can be introduced by residual bandwidth (over-reserved but unused) of each Class of Service (CoS). Moreover, admission control can be compromised by inefficient over-reservation control mechanism, where excessive signaling can be placed under severe network conditions, such as congestion periods. In this scope, this paper proposes a novel Class-based resource Over-pRovisioning (COR) mechanism with novel techniques to: (a) over-provision CoSs by computing appropriate bandwidth over-allocation; (b) redistribute residual bandwidth among CoSs to avoid wasting resources. The performance evaluation shows the superiority of COR proposal over state-of-the-art solutions in optimizing the overall network performance, while preventing from bandwidth waste and unnecessary sessions blocking.

Analysis of the Impact of Denial of Service Attacks on Centralized Control in Smart Cities

The increasing threat of Denial of Service (DoS) attacks targeting Smart City systems impose unprecedented challenges in terms of service availability, especially against centralized control platforms due to their single point of failure issue. The European ARTEMIS co-funded project ACCUS (Adaptive Cooperative Control in Urban (sub) Systems) is focused on a centralized Integration and Coordination Platform (ICP) for urban subsystems to enable real-time collaborative applications across them and optimize their combined performance in Smart Cities. Hence, any outage of the ACCUS ICP, due to DoS attacks, can severely affect not only the interconnected subsystems but also the citizens. Consequently, it is of utmost importance for ACCUS ICP to be protected with the appropriate defense mechanisms against these attacks. Towards this direction, the measurement of the performance degradation of the attacked ICP server can be used for the selection of the most appropriate defense mechanisms. However, the suitable metrics are required to be defined. Therefore, this paper models and analyzes the impact of DoS attacks on the queue management temporal performance of the ACCUS ICP server in terms of system delay by using queueing theory.

Cooperative Strategies for End-to-End Energy Saving and QoS Control

Energy efficiency and Quality of Service (QoS) have become major requirements in the research and commercial community to develop green communication technologies for cost-effective and seamless convergence of all services (e.g., data, 3D media, Haptics, etc.) over the Internet. In particular, efforts in wireless networks demonstrate that energy saving can be achieved through cooperative communication techniques such as multihop communications or cooperative relaying. Game-theoretic techniques are known to analyze interactions between collaborating entities in which each player can dynamically adopt a strategy that maximizes the number of bits successfully transmitted per unit of energy consumed, contributing to the overall optimization of the network in a distributed fashion. As for the core networks, recent findings claimed that resource over-provisioning is promising since it allows for dynamically booking more resources in advance, and multiple service requests can be admitted in a network without incurring the traditional per-flow signaling, while guaranteeing differentiated QoS. Indeed, heavy control signaling load has recently raised unprecedented concerns due to the related undue processing overhead in terms of energy, CPU and memory consumption. While cooperative communication and resource over-provisioning have been researched for many years, the former focuses on wireless access and the latter on the wired core networks only. Therefore, this chapter investigates existing solutions in these fields and proposes new design approach and guidelines to integrate both access and core technologies in such a way as to provide a scalable and energy-efficient support for end-to-end QoS-enabled communication control. This is of paramount importance to ensure rapid development of attractive 3D media streaming in the current and future Internet.

Scalable Resource and Admission Control in Class-Based Differentiated Networks

Dynamic aggregate bandwidth over-reservation is a scalable approach for Quality of Service (QoS) control mechanisms, since surplus of reservation allows for admitting several flows without signaling the network. Our recent work, the Advanced Class-based resource Over-Reservation (ACOR), shows interesting results by significantly reducing QoS control signaling overhead with increased resource utilization without incurring QoS violation when compared with related state-of-the-art patented solution. However, ACOR is too sensitive to the number of paths that share bottleneck links. It also resorts to per-flow signaling when links are congested. In view of this, we propose the Extended-ACOR (EACOR), which extends ACOR architecture with a new approach, aiming at reducing the performance dependency on paths’ density on bottleneck interfaces. Moreover, it is able to efficiently track congestion information throughout a network to prevent unnecessary signaling during network congestion time. Thus, E-ACOR is expected to scale large networks with reduced signaling. Also, E-ACOR is able to keep all the benefits of ACOR in terms of support for QoS differentiation, QoS violation avoidance and resource utilization efficiency. Analytical and simulation results demonstrate the efficiency and cost-effectiveness of E-ACOR over ACOR, by significantly reducing signaling frequency especially during critical periods of congestion while enabling service convergence with differentiation of the control.

Context-Aware Session and Network Control in Future Internet

With the rapidly increasing interest of citizens and businesses in multimedia group services, personalization, context- awareness and seamless mobility, the communication can no longer be limited to high speed network or devices. In future scenarios, context-aware services and multicasting will together drive a new trend, since context-awareness can exploit situations in which users share the same interests and request similar services, increasing the effectiveness of session and network control. However, context-aware networks impose several challenges: any change to context, such as, location, mobility, velocity, preferences, presence, etc., can change the overall services and network environments, requiring completely restructuring of the network and multicast sessions in a very dynamic way. This dynamicity imposes scalability problems in current networks. In this paper, we present an initial future Internet architecture for context-aware network and service control, which enables the support of context-aware users and services, seamless reacting to the context changes with minimal impacts to the services and multicast control. For this purpose, we provide a network that is able to interact with context-based services, choose and change the session and network characteristics based on the context, both for the environment, user, network, and sessions. To address the dynamicity of the network, we provide the support of multicast abstract transport trees able to abstract the network changes to the running sessions transport, and limiting the impact of all the context dynamics in the user sessions.

Multiview real-time media distribution for next generation networks

With the massive deployment of broadband access to the end-users, the continuous improvement of the hardware capabilities of end devices and better video compression techniques, acceptable conditions have been met to unleash over-the-top bandwidth demanding and time-stringent P2P applications, such as multiview real-time media distribution. Such applications enable the transmission of multiple views of the same scene, providing consumers with a more immersive visual experience. This article proposes an architecture to distribute multiview real-time media content using a hybrid DVB-T2, client-server and P2P paradigms, supported by an also novel QoS solution. The approach minimizes packet delay, interarrival jitter, inter-ISP traffic and traffic at the ISP core network, which are some of the main drawbacks of P2P networks, whilst still meeting stringent QoS demands. The proposed architecture uses DVB-T2 to distribute a self-contained and fully decodable base-layer video signal, assumed to be always available to the end-user, and an IP network to distribute in parallel - with increased delay - additional IP video streams. The result is a decoded video quality that adapts to individual end-user conditions and maximizes viewing experience. To achieve its target goal this architecture: defines new services for the ISPs services network and new roles for the ISP core, edge and border routers; makes use of pure IP multicast transmission at the ISPs core network, greatly minimizing bandwidth consumption; constructs a geographically contained P2P network that uses P2P application-level multicast trees to assist the distribution of the IP video streams at the ISP access networks, greatly reducing inter-ISP traffic, and; describes a novel QoS control architecture that takes advantage of the Internet resource over-provisioning techniques to meet stringent QoS demands in a scalable manner. The proposed architecture has been implemented in both real test bed implementation and ns-2 simulations. Results have shown a highly scalable P2P overlay construction algorithm, with very fast computation of application-level multicast trees (in the order of milliseconds), and efficient reaction to peer-churn with no perceptually annoying impairments noticed. Furthermore, enormous bandwidth savings are achieved at the ISP core network, which considerable lower management and investment costs in infrastructure. The QoS based results have also shown that the proposed approach effectively deploys a fast and scalable resource and admission control mechanism, considerably lowering signalling events using a per-class over-provisioning approach thus preventing per-flow QoS reservation signalling messages. Moreover, it is aware of network link resources in real-time and supports for service differentiation and network convergence by guaranteeing that each admitted traffic flow receives the contracted QoS. Finally, the proposed architecture for Multiview Real-Time Media Distribution for Next Generation Networks, as a component for a large project demonstrator, has been evaluated by an independent panel of experts following ITU recommendations, obtaining an excellent evaluation as computed by Mean Opinion Score.

Dynamic QoS Support for P2P Communications

Scalable Quality of Service (QoS) control is of paramount importance to effectively enable a seamless convergence of the rapidly evolving Peer-to-Peer (P2P) overlay communications over the Internet since the latter only supports best-effort service paradigm. For example, the European Union (EU) funded ROMEO project is focusing on a joint use of DVB-T2 and P2P overlay networks for live multimedia content sharing and collaboration among multiple users. This raises a strong need that the media packets transmitted through the P2P overlay delivery system must arrive earlier enough at the end users to assure a proper synchronization of the multiple views that may be received via the hybrid network. For this purpose, the P2P network must assure a certain QoS guarantee in terms of bandwidth, delay, jitter, and loss. More importantly, the control must be scalable to prevent excessive signalling and the related processing overhead, usually suffered in the traditional per-flow QoS control approaches. In this view, recent research effort claimed that the Internet resources can be efficiently over-provisioned (booking more resources in-advance) in such a way to allow differentiation of QoS control with reduced signalling overhead and increased resource utilization. This approach, however, needs further investigations for proper integration into innovative networking architectural designs to achieve performance. In addition to that, and in order to provide an end-to-end QoS, a mechanism to enforce prioritization policies within the customer’s access network is also needed. Hence, this chapter proposes a cross-layer control architecture that takes advantage of the Internet resources over-provisioning and the QoS policy enforcement within access networks to facilitate rapid development of P2P applications. The design aims to alleviate the requirements of buffers and the need for adaptation on end users’ devices, thus allowing for cost-effective and rapid development of attractive services in similar hybrid content delivery networks.

Hybrid framework for scalable resource control in multi-ingress networks

Attempts by the research community to meet expectations arising from future Internet systems, and specifically to provide Quality of Service (QoS) for multimedia multi-user sessions, have resulted in mechanisms such as MultiUser Aggregated Resource Allocation (MARA). Its results have been promising, mainly because it drastically reduces signaling and processing overhead, despite its limitations in multi-ingress scenarios. In view of these benefits, this paper proposes the MultiUser Aggregated Resource Allocation - Multi-Ingress to overcome the main limitations of MARA so that it can serve as a promising tool in current and future IP-based network systems. The simulation experiments carried out for MARA-MI demonstrated the benefits in optimizing bandwidth use and networking costs while maintaining QoS over time in multiple sessions, in comparison to a relevant related work.