On the Placement of Management and Control Functionality in Software Defined Networks

In order to support reactive and adaptive operations, Software-Defined Networking (SDN)-based management and control frameworks call for decentralized solutions. A key challenge to consider when deploying such solutions is to decide on the degree of distribution of the management and control functionality. In this paper, we develop an approach to determine the allocation of management and control entities by designing two algorithms to compute their placement. The algorithms rely on a set of input parameters which can be tuned to take into account the requirements of both the network infrastructure and the management applications to execute in the network. We evaluate the influence of these parameters on the configuration of the resulting management and control planes based on real network topologies and provide guidelines regarding the settings of the proposed algorithms

CacheMAsT: Cache Management Analysis and Visualization Tool

Recent approaches have proposed to empower Internet Service Providers (ISPs) with caching capabilities that can allow them to implement their own cache management strategies and as such have better control over the utilization of their resources. In this demo paper, we present CacheMAsT (Cache Management Analysis and Visualization Tool), a decision support tool to visualize the configuration and performance of in-network cache management approaches. CacheMAsT is aimed at assisting researchers and engineers in analyzing and evaluating the different factors that can affect the performance of a cache management strategy and ultimately decide on the optimal approach to apply

Proactive multi-tenant cache management for virtualized ISP networks

The content delivery market has mainly been dominated by large Content Delivery Networks (CDNs) such as Akamai and Limelight. However, CDN traffic exerts a lot of pressure on Internet Service Provider (ISP) networks. Recently, ISPs have begun deploying so-called Telco CDNs, which have many advantages, such as reduced ISP network bandwidth utilization and improved Quality of Service (QoS) by bringing content closer to the end-user. Virtualization of storage and networking resources can enable the ISP to simultaneously lease its Telco CDN infrastructure to multiple third parties, opening up new business models and revenue streams. In this paper, we propose a proactive cache management system for ISP-operated multi-tenant Telco CDNs. The associated algorithm optimizes content placement and server selection across tenants and users, based on predicted content popularity and the geographical distribution of requests. Based on a Video-on-Demand (VoD) request trace of a leading European telecom operator, the presented algorithm is shown to reduce bandwidth usage by 17% compared to the traditional Least Recently Used (LRU) caching strategy, both inside the network and on the ingress links, while at the same time offering enhanced load balancing capabilities. Increasing the prediction accuracy is shown to have the potential to further improve bandwidth efficiency by up to 79%

Managing the Future Internet through Intelligent In-Network Substrates

The current Internet has been founded on the architectural premise of a simple network service used to interconnect relatively intelligent end systems. While this simplicity allowed it to reach an impressive scale, the predictive manner in which ISP networks are currently planned and configured through external management systems and the uniform treatment of all traffic are hampering its use as a unifying multi-service network. The future Internet will need to be more intelligent and adaptive, optimizing continuously the use of its resources and recovering from transient problems, faults and attacks without any impact on the demanding services and applications running over it. This article describes an architecture that allows intelligence to be introduced within the network to support sophisticated self-management functionality in a coordinated and controllable manner. The presented approach, based on intelligent substrates, can potentially make the Internet more adaptable, agile, sustainable, and dependable given the requirements of emerging services with highly demanding traffic and rapidly changing locations. We discuss how the proposed framework can be applied to three representative emerging scenarios: dynamic traffic engineering (load balancing across multiple paths); energy efficiency in ISP network infrastructures; and cache management in content-centric networks

Paradoxical and powerful: Volunteers’ experiences of befriending people with dementia

This qualitative UK study explored the lived experiences of volunteer befrienders to people with dementia, using interpretative phenomenological analysis. Individual semi-structured interviews were conducted with nine befrienders aged between 25 and 66 years. The relationship that developed between befriender and befriendee was at the heart of befrienders’ experiences. It comprised numerous paradoxical processes that generated issues of power, equality and boundaries, characterising befriending as a complex and unique phenomenon. Befriending was expressed as a deeply personal and human experience, often with emotional power and profound meaning. Befrienders’ personal learning included seeing past dementia stereotypes, challenging their own assumptions and boundaries, and reflecting on love, life and humanness. Dissemination of these findings could help to challenge the stigma around dementia, and enhance recruitment and support of dementia befrienders. Future research should consider befriendee experiences of the relationship, additional measures of befriending effectiveness, and exploration of befriender attrition and support. </jats:p

Decentralized Solutions for Monitoring Large-Scale Software-Defined Networks

Software-Defined Networking (SDN) technologies offer the possibility to automatically and frequently reconfigure the network resources by enabling simple and flexible network programmability. One of the key challenges to address when developing a new SDN-based solution is the design of a monitoring framework that can provide frequent and consistent updates to heterogeneous management applications. To cope with the requirements of large-scale networks (i.e. large number of geographically dispersed devices), a distributed monitoring approach is required. This PhD aims at investigating decentralized solutions for resource monitoring in SDN. The research will focus on the design of monitoring entities for the collection and processing of information at different network locations and will investigate how these can efficiently share their knowledge in a distributed management environment

Extensible Signaling Framework for Decentralized Network Management Applications

The management of network infrastructures has become increasingly complex over time, which is mainly attributed to the introduction of new functionality to support emerging services and applications. To address this important issue, research efforts in the last few years focused on developing Software-Defined Networking solutions. While initial work proposed centralized architectures, their scalability limitations have led researchers to investigate a distributed control plane, with controller placement algorithms and mechanisms for building a logically centralized network view, being examples of challenges addressed. A critical issue that has not been adequately addressed concerns the communication between distributed decision-making entities to ensure configuration consistency. To this end, this paper proposes a signaling framework that can allow the exchange of information in distributed management and control scenarios. The benefits of the proposed framework are illustrated through a realistic network resource management use case. Based on simulation, we demonstrate the flexibility and extensibility of our solution in meeting the requirements of distributed decision-making processes

Information-aware access network selection

Mobile devices are increasingly presented with multiple connectivity options, including WiFi hotspots, micro-/macro-cells or even other devices in device-to-device (D2D) communications. By and large, connectivity management for mobile devices has primarily focused on contention, congestion and wireless medium conditions. In this paper, we assess the role of information-centrism in mobile device connectivity management. Motivated by the increasing availability of content and services in in-network caches and micro-data centres, we design an access network selection scheme that takes into account information availability within each connectivity option. Our simulations show that information-awareness results in a significant increase of cache hit ratios by up to 115% in certain scenarios

Damage analysis of pressure pipes under high temperature and variable pressure conditions

The problem of non-linear stress analysis of creeping reinforced pipes under constant pressure has been treated in a recent work [1]. In the present work, a damage accumulation analysis of the above problem is attempted taking into account the non-linear distribution of the stresses as well as non-linear damage accumulation under variable pressure and/or temperature conditions. For the stress analysis a non-linear differential equation is used to derive the stress concentration in critical locations of power pipes reinforced by rigid rings which are distributed along their axis. Due to step-wised temperature and internal pressure of the pipe, the damage accumulation is predicted by using a damage function specified with respect to damage parameter derived by the stress versus Larson-Miller coefficient curve. Advantages of the proposed methodology are: (a) the 2-D creep stress analysis incorporates mechanical behaviours of material derived by uniaxial tests, (b) the predicted damage accumulation due to the variable pressure takes into account the previous damage history as well as the loading order effect

On the feasibility of a user-operated mobile content distribution network

The vast majority of mobile data transfers today follow the traditional client-server model. Although in the fixed network P2P approaches have been exploited and shown to be very efficient, in the mobile domain there has been limited attempt to leverage on P2P (D2D) for large-scale content distribution (i.e., not DTN-like, point-to-point message transfers). In this paper, we explore the potential of a user-operated, smartphone-centric content distribution model for smartphone applications. In particular, we assume source nodes that are updated directly from the content provider (e.g., BBC, CNN), whenever updates are available; destination nodes are then directly updated by source nodes in a D2D manner. We leverage on sophisticated information-aware and application-centric connectivity techniques to distribute content between mobile devices in densely-populated urban environments. Our target is to investigate the feasibility of an opportunistic content distribution network in an attempt to achieve widespread distribution of heavy content (e.g., video files) to the majority of the destination nodes. We propose ubiCDN as a ubiquitous, user-operated and distributed CDN for mobile applications