René Serral-Gracià

An overview of quality of experience measurement challenges for video applications in IP networks

The increase in multimedia content on the Internet has created a renewed interest in quality assessment. There is however a main difference from the traditional quality assessment approaches, as now, the focus relies on the user perceived quality, opposed to the network centered approach classically proposed. In this paper we overview the most relevant challenges to perform Quality of Experience (QoE) assessment in IP networks and highlight the particular considerations necessary when compared to alternative mechanisms, already deployed, such as Quality of Service (QoS). To assist on the handling of such challenges we first discuss the different approaches to Quality of Experience assessment along with the most relevant QoE metrics, and then we discuss how they are used to provide objective results about user satisfaction.

Key ingredients in an IoT recipe: Fog Computing, Cloud computing, and more Fog Computing

This paper examines some of the most promising and challenging scenarios in IoT, and shows why current compute and storage models confined to data centers will not be able to meet the requirements of many of the applications foreseen for those scenarios. Our analysis is particularly centered on three interrelated requirements: 1) mobility; 2) reliable control and actuation; and 3) scalability, especially, in IoT scenarios that span large geographical areas and require real-time decisions based on data analytics. Based on our analysis, we expose the reasons why Fog Computing is the natural platform for IoT, and discuss the unavoidable interplay of the Fog and the Cloud in the coming years. In the process, we review some of the technologies that will require considerable advances in order to support the applications that the IoT market will demand.

A survey and taxonomy of ID/Locator Split Architectures

The IP-based addressing scheme currently supporting the whole routing architecture embeds some well-known limitations that may significantly hinder the deployment of new applications and services on the Internet. Indeed, it is widely accepted that the unstoppable growth of Internet users is producing two well-known problems: (1) depletion of addresses, motivated by a design limitation of the currently deployed addressing scheme, and (2) the semantic overload of addresses. The main negative consequences of these problems may be summarized as: (i) exacerbating the geometrical growth of the routing tables, and (ii) affecting other network features, such as traffic engineering and mobility, in terms of resilience and disruption tolerant communications. The relevant consequences that addressing brings to the overall network operation is pushing the networking community to study and propose new addressing architectures that may limit or even remove the negative effects (affecting network performance) stemmed from the currently deployed addressing architecture. To this end, researchers working on this area must have a perfect understanding of the weaknesses and limitations coming up from the nowadays architecture as well as a comprehensive knowledge of the alternatives proposed so far along with the most appealing research trends. Aligned to this scenario, this paper comes up with the aim of assisting the reader to both: (i) get insights about the most prominent limitations of the currently deployed addressing architecture, and (ii) survey the existing proposals based on ID/Locator Split Architectures (ILSAs) including an analysis of pros and cons, as well as a taxonomy aiming at formulating a design space for evaluating and designing existing and future ILSAs.

Network Management Challenges and Trends in Multi-Layer and Multi-Vendor Settings for Carrier-Grade Networks

The exponential growth of Internet traffic gives no respite to the telecommunications industry and is visibly shortening the life-cycle of the technologies used for core networking. To cope with the traffic demand, the industry has primarily focused on the evolution of the data and control planes, and has rapidly made progress in both subjects. However, the innovations in the market have not reached the management plane at the same speed. This stems from a number of factors, most of which point to the segmentation of competencies in managing multi-layer infrastructures. Current carrier-grade networks are organized as multi-layer infrastructures, typically composed of two layers: IP routers deployed in tandem with optical transport nodes. In turn, each of the two layers is typically composed of devices from different vendors, each of which usually supplies its own (proprietary) network management system (NMS). In practice, the lack of broadly accepted mechanisms for enabling interoperability among the different NMSs has led to the isolation of these proprietary systems. As a result, the operation and maintenance tasks on the network are becoming increasingly complex, which is leading to duplication of functions, higher OPEX, and significant delays in the coordination of multi-layer provisioning processes. In this paper, we examine in detail the interoperability challenges of managing multi-layer and multi-vendor carrier-grade networks, and review the current trends and recent standards in the area, with strong focus on industrial advances. We cover the Multi-Technology Operations System Interface (MTOSI) as well as OpenFlow, and analyze their potential impact and reach. We also discuss some of the reasons why relevant carrier-grade management proposals have not been able to fulfill the requirements of Internet service providers (ISPs), and identify a set of features that might help pave the way to market for new management products.

Measurement based analysis of the handover in a WLAN MIPv6 scenario

This paper studies the problems related to mobile connectivity on a wireless environment with Mobile IPv6, specially the handover, which is the most critical part. The main goal of this paper is to develop a structured methodology for analyzing 802.11/IPv6/MIPv6 handovers and their impact on applications level. This is accomplished by capturing traffic on a testbed and analyzing it with two applications developed for this purpose. The analysis covers passive and active measurements. This methodology is applicable for measuring improvements on handover (such as Fast Handovers for Mobile IPv6, Hierarchical Mobile IPv6 or 802.11 handover).

Reducing the effects of routing inaccuracy by means of prediction and an innovative link-state cost

The routing inaccuracy problem is one of the major issues impeding the evolution and deployment of Constraint-Based Routing (CBR) techniques. This paper proposes a promising CBR strategy that combines the strengths of prediction with an innovative link-state cost. The latter explicitly integrates a two-bit counter predictor, with a novel metric that stands for the degree of inaccuracy (seen by the source node) of the state information associated with the links along a path. In our routing model, Link-State Advertisements (LSAs) are only distributed upon topological changes in the network, i.e., the state and availability of network resources along a path are predicted from the source rather than updated through conventional LSAs. As a proof-of-concept, we apply our routing strategy in the context of circuit-switched networks. We show that our approach considerably reduces the impact of routing inaccuracy on the blocking probability, while eliminating the typical LSAs caused by the traffic dynamics in CBR protocols.

Unlocking the Value of Open Data with a Process-Based Information Platform

There has been a wide shift in the way data are managed in the public administration. The move has led to an increased adoption of the Open Data model, where public administrations freely and openly publish data gathered using citizen taxes. However, undesirable side effects include the lack of data quality, incompatible formats and access methods, and various semantic interpretations of data. As a consequence, Open Data stakeholders, such as application developers, common citizens and even government agencies themselves, are overwhelmed by the large quantity of unstructured data, unable offer citizens and business value-added applications and services. To address the issue and make Open Data actionable, this paper proposes a systematic value-creation process that helps stakeholders identify the most suitable information assets and convert them into forms that can be more consumable by users. The process is enabled by the Middleware for Open-Data Aggregation (MODA), a platform designed with four main features, i) data quality assessment, ii) data homogenization for uniform access through an universal interface, iii) data correlation and semantic adaptation, and iv) secure data access. These features maximize the return on investment in Open Data by reducing time and cost of third party application development while providing improvement feedback to data sources.

Network performance assessment using adaptive traffic sampling

Multimedia and real-time services are spreading all over the Internet. The delivery quality of such contents is closely related to its network performance, for example in terms such as low latency or few packet losses. Both customers and operators want some feedback from the network in order to assess the real provided quality. There are proposals about distributed infrastructures for the on-line reporting of these quality metrics. The issue all these infrastructures must face is the high resource requirements to keep up with accurate and live reporting. This paper proposes an adaptive sampling methodology to control the resources needed for the network performance reporting. Moreover, the solution keeps up with accurate live reporting of the main network performance metrics. The solution is tested in a European wide testbed with real traffic which permits to assess the accuracy and to study the resources consumption of the system.

Evaluation of the fast handover implementation for mobile IPv6 in a real testbed

Fast Handovers is an enhancement to the Mobile IPv6 protocol, currently specified in an IETF draft, which reduces the handover latency. This can be beneficial to real-time applications. This paper presents a novel implementation of Fast Handovers and an analysis of the handover. Using a real testbed we study the handover latency and the provided QoS: analyzing the OWD, IPDV and Packet Loss before and after the handover. Finally we present a comparison between the Mobile IPv6 and the Fast Handovers handover.

Packet Loss Estimation Using Distributed Adaptive Sampling

Packet losses are a critical metric for network performance assessment. In this paper we present a novel methodology to accurately estimate the packet loss ratio in realtime in a fully distributed scenario. The constraint such systems must face is the large amount of resources required for keeping live performance assessment. Our contribution has two main parts. On the one hand we study the behaviour of packet losses among the traffic sharing a path, and extend the classical definition of loss burst by the concept of density. On the other hand, with the knowledge acquired in the loss distribution study, we present an adaptive sampling technique that schedules the network resources in order to distributely estimate the packet losses with reasonable accuracy. In order to validate the proposal we perform some real tests over an European-wide testbed. The results show a great improvement in packet loss estimation over previous research, while using a controlled amount of resources.