Measuring the Relationships between Internet Geography and RTT

When designing distributed systems and Internet protocols, designers can benefit from statistical models of the Internet that can be used to estimate their performance. However, it is frequently impossible for these models to include every property of interest. In these cases, model builders have to select a reduced subset of network properties, and the rest will have to be estimated from those available. In this paper we present a technique for the analysis of Internet round trip times (RTT) and its relationship with other geographic and network properties. This technique is applied on a novel dataset comprising ∼19 million RTT measurements derived from ∼200 million RTT samples between ∼54 thousand DNS servers. Our main contribution is an information-theoretical analysis that allows us to determine the amount of information that a given subset of geographic or network variables (such as RTT or great circle distance between geolocated hosts) gives about other variables of interest. We then provide bounds on the error that can be expected when using statistical estimators for the variables of interest based on subsets of other variables

RFID in the Cloud: A Service for High-Speed Data Access in Distributed Value Chains

Radio-Frequency Identification (RFID) is emerging as an important technology for exchanging information about physical objects along distributed value chains. The influential standardization organization EPCglobal has released standards for RFID-based data exchange that follow the data-on-network paradigm. Here, the business-relevant object data is provided by network services, whereas RFID tags are only used to carry a reference number for data retrieval via the Internet. However, as we show in this paper, this paradigm can result in long response times for data access. We present experiments that explore what factors impact the response times and identify obstacles in current architectures. Based on these analyses, we designed a cloud-based service that realizes high-speed data access for data-on-network solutions. We further present simulation experiments analyzing the benefits of our cloud-based concept with regards to fast RFID-data access and reduced infrastructure cost through scale effects

Le modèle Inframétrique pour Internet

National audienceDe nombreux algorithmes ont été récemment conçus pour l'Internet sous l'hypothèse que la mesure du temps d'aller retour (RTT) est une distance. De plus, nombre de ces algorithmes (construction de réseau logique, conception de schéma de routage compact, construction de couverture ayant peu d'arêtes) reposent sur l'hypothèse que la métrique d'Internet a une croissance de boule ou une dimension doublante bornée. Cet article étudie la validité de ces hypothèses et propose un modèle formel et analysable qui correspond aux observations expérimentales. La version complète de cet article est [2]: http://www.liafa.jussieu.fr/~elebhar/exposes/inframetric.pdf

Position referenced force augmentation in teleoperated hydraulic manipulators operating under delayed and lossy networks: a pilot study.

Position error between motions of the master and slave end-effectors is inevitable as it originates from hard-to-avoid imperfections in controller design and model uncertainty. Moreover, when a slave manipulator is controlled through a delayed and lossy communication channel, the error between the desired motion originating from the master device and the actual movement of the slave manipulator end-effector is further exacerbated. This paper introduces a force feedback scheme to alleviate this problem by simply guiding the operator to slow down the haptic device motion and, in turn, allows the slave manipulator to follow the desired trajectory closely. Using this scheme, the master haptic device generates a force, which is proportional to the position error at the slave end-effector, and opposite to the operator's intended motion at the master site. Indeed, this force is a signal or cue to the operator for reducing the hand speed when position error, due to delayed and lossy network, appears at the slave site. Effectiveness of the proposed scheme is validated by performing experiments on a hydraulic telemanipulator setup developed for performing live-line maintenance. Experiments are conducted when the system operates under both dedicated and wireless networks. Results show that the scheme performs well in reducing the position error between the haptic device and the slave end-effector. Specifically, by utilizing the proposed force, the mean position error, for the case presented here, reduces by at least 92% as compared to the condition without the proposed force augmentation scheme. The scheme is easy to implement, as the only required on-line measurement is the angular displacement of the slave manipulator joints

Exploiting Rateless Codes in Cloud Storage Systems

devices (virtual disks) that can be directly accessed and used as if they were raw physical disks. In this paper we devise ENIGMA, an architecture for the back-end of BLCS systems able to provide adequate levels of access and transfer performance, availability, integrity, and confidentiality, for the data it stores. ENIGMA exploits LT rateless codes to store fragments of sectors on storage nodes organized in clusters. We quantitatively evaluate how the various ENIGMA system parameters affect the performance, availability, integrity, and confidentiality of virtual disks. These evaluations are carried out by using both analytical modeling (for availability, integrity, and confidentiality) and discrete event simulation (for performance), and by considering a set of realistic operational scenarios. Our results indicate that it is possible to simultaneously achieve all the objectives set forth for BLCS systems by using ENIGMA, and that a careful choice of the various system parameters is crucial to achieve a good compromise among them. Moreover, they also show that LT coding-based BLCS systems outperform traditional BLCS systems in all the aspects mentioned before

ZigZag: A Middleware for Service Discovery in Future Internet

International audienceOver the last few years, social networks, mobile devices and personalized services have been heavily responsible for a substantial in- crease in remote services available over Internet. Consequently, service consumers have to discover remote services anytime, anywhere across networks boundaries making thus service discovery, and their underlying Service Discovery Protocols (SDPs) more important than ever. In this paper, we introduce ZigZag, a middleware to reuse and extend current SDP, designed for local networks, to discover available services across network boundaries as required in Future Internet. Our approach is based on protocol translation to enable service discovery irrespective of their underlying SDP. Further, we provide a thorough evaluation to validate our approach