28 research outputs found
PABO: Mitigating Congestion via Packet Bounce in Data Center Networks
In today's data center, a diverse mix of throughput-sensitive long flows and
delay-sensitive short flows are commonly presented in shallow-buffered
switches. Long flows could potentially block the transmission of
delay-sensitive short flows, leading to degraded performance. Congestion can
also be caused by the synchronization of multiple TCP connections for short
flows, as typically seen in the partition/aggregate traffic pattern. While
multiple end-to-end transport-layer solutions have been proposed, none of them
have tackled the real challenge: reliable transmission in the network. In this
paper, we fill this gap by presenting PABO -- a novel link-layer design that
can mitigate congestion by temporarily bouncing packets to upstream switches.
PABO's design fulfills the following goals: i) providing per-flow based flow
control on the link layer, ii) handling transient congestion without the
intervention of end devices, and iii) gradually back propagating the congestion
signal to the source when the network is not capable to handle the
congestion.Experiment results show that PABO can provide prominent advantage of
mitigating transient congestions and can achieve significant gain on end-to-end
delay
Providing security and fault tolerance in P2P connections between clouds for mHealth services
[EN] The mobile health (mHealth) and electronic health (eHealth) systems are useful to maintain a correct administration of health information and services. However, it is mandatory to ensure a secure data transmission and in case of a node failure, the system should not fall down. This fact is important because several vital systems could depend on this infrastructure. On the other hand, a cloud does not have infinite computational and storage resources in its infrastructure or would not provide all type of services. For this reason, it is important to establish an interrelation between clouds using communication protocols in order to provide scalability, efficiency, higher service availability and flexibility which allow the use of services, computing and storage resources of other clouds. In this paper, we propose the architecture and its secure protocol that allows exchanging information, data, services, computing and storage resources between all interconnected mHealth clouds. The system is based on a hierarchic architecture of two layers composed by nodes with different roles. The routing algorithm used to establish the connectivity between the nodes is the shortest path first (SPF), but it can be easily changed by any other one. Our architecture is highly scalable and allows adding new nodes and mHealth clouds easily, while it tries to maintain the load of the cloud balanced. Our protocol design includes node discovery, authentication and fault tolerance. We show the protocol operation and the secure system design. Finally we provide the performance results in a controlled test bench.Lloret, J.; Sendra, S.; Jimenez, JM.; Parra-Boronat, L. (2016). Providing security and fault tolerance in P2P connections between clouds for mHealth services. Peer-to-Peer Networking and Applications. 9(5):876-893. doi:10.1007/s12083-015-0378-3S87689395The Fifty-eighth World Health Assembly, Resolutions and Decisions. Document: A58/21. Available at: http://www.who.int/healthacademy/media/WHA58-28-en.pdf . [Last access: Dec. 30, 2014]World Health organization. Topics of eHealth. In WHO website. Available at: http://www.who.int/topics/eHealth/en/ . [Last access: Dec. 30, 2014]Pickup JC, Freeman SC, Sutton AJ (2011) Glycaemic control in type 1 diabetes during real time continuous glucose monitoring compared with self monitoring of blood glucose: meta-analysis of randomised controlled trials using individual patient data. BMJ 343:d3805Promotional Material Digital health: working in partnership. Department of Health. UK. (2014) Available at: https://www.gov.uk/government/publications/digital-health-working-in-partnership/digital-health-working-in-partnerships#digital-health---harnessing-technology-for-patient-benefit . [Last access: Dec. 30, 2014]eHealth for a Healthier Europe!– opportunities for a better use of healthcare resources. Available at: https://joinup.ec.europa.eu/sites/default/files/files_epractice/sites/eHealth%20for%20a%20Healthier%20Europe %20-%20Opportunities%20for%20a%20better%20use%20of%20healthcare%20resources.pdf. [Last access: Dec. 30, 2014]Adibi S (2012) Link technologies and BlackBerry mobile health (mHealth) solutions: a review. IEEE Trans Inf Technol Biomed 16(4):586–597Chiarini G, Ray P, Akter S, Masella C, Ganz A (2013) mHealth technologies for chronic diseases and elders: a systematic review. IEEE J Sel Areas Commun 31(9):6–18Lopes IM, Silva BM, Rodrigues JJ, Lloret J, Proenca ML (2011) A mobile health monitoring solution for weight control. In proceedings of the 2011 International Conference on Wireless Communications and Signal Processing (WCSP 2011), Nanjing, pp 1–5Lopes IM, Silva BM, Rodrigues JJPC, Lloret J (2012) Performance evaluation of cooperation mechanisms for m-health applications. In proceedings of the 2012 I.E. Global Communications Conference (GLOBECOM 2012), AnaheimKyriacou EC, Pattichis CS, Pattichis MS (2009) An overview of recent health care support systems for eEmergency and mHealth applications. In proceedings of the 31st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC 2009), Hilton Minneapolis, pp 1246–1249Nkosi MT, Mekuria F (2010) Cloud computing for enhanced mobile health applications. In proceedings of the 2010 I.E. Second International Conference on Cloud Computing Technology and Science (CloudCom 2010), Indianapolis, pp 629–633Sultan N (2014) Making use of cloud computing for healthcare provision: opportunities and challenges. Int J Inf Manag 34(2):177–184Pandey S, Voorsluys W, Niu S, Khandoker A, Buyya R (2012) An autonomic cloud environment for hosting ECG data analysis services. Futur Gener Comput Syst 28(1):147–154Xia H, Asif I, Zhao X (2013) Cloud-ECG for real time ECG monitoring and analysis. Comput Methods Prog Biomed 110(3):253–259Bourouis A, Feham M, Bouchachia A (2012) A new architecture of a ubiquitous health monitoring system: a prototype of cloud mobile health monitoring system. arXiv preprint. Reference: arXiv:1205.6910Chen KR, Lin YL, Huang MS (2011) A mobile biomedical device by novel antenna technology for cloud computing resource toward pervasive healthcare. In proceedings of the 11th International Conference on Bioinformatics and Bioengineering (BIBE 2011), Taichung, pp 133–136Lacuesta R, Lloret J, Sendra S, Peñalver L (2014), Spontaneous ad hoc mobile cloud computing network. Sci World J (Article ID 232419): 1–19Ghafoor KZ, Bakar KA, Mohammed MA, Lloret J (2013) Vehicular cloud computing: trends and challenges (Chapter 14). In Mobile Networks and Cloud computing Convergence for Progressive Services and Applications. IGI Global. pp. 262–274. DOI: 10.4018/978-1-4666-4781-7.ch014Wan J, Zhang D, Zhao S, Yang LT, Lloret J (2014) Context-aware vehicular cyber-physical systems with cloud support: architecture, challenges and solutions. IEEE Commun Mag 52(8):106–113. doi: 10.1109/MCOM.2014.6871677Rodrigues JJPC, Zhou L, Mendes LDP, Lin K, Lloret J (2012) Distributed media-aware flow scheduling in cloud computing environment. Comput Commun 35(15):1819–1827Dutta R, Annappa B (2014) Protection of data in unsecured public cloud environment with open, vulnerable networks using threshold-based secret sharing. Netw Protoc Algoritm 6(1):58–75Modares H, Lloret J, Moravejosharieh A, Salleh R (2013) Security in mobile cloud computing (Chapter 5). In Mobile Networks and Cloud computing Convergence for Progressive Services and Applications. IGI Global. pp. 79–91Mehmood A, Song H, Lloret J (2014) Multi-agent based framework for secure and reliable communication among open clouds. Netw Protoc Algoritm 6(4):60–76Mendes LDP, Rodrigues JJPC, Lloret J, Sendra S (2014) Cross-layer dynamic admission control for cloud-based multimedia sensor networks. IEEE Syst J 8(1):235–246Xiong J, Li F, Ma J, Liu X, Yao Z, Chen PS (2014) A full lifecycle privacy protection scheme for sensitive data in cloud computing. Peer-to-Peer Netw Appl 1–13Yang H, Kim H, Mtonga K (2014) An efficient privacy-preserving authentication scheme with adaptive key evolution in remote health monitoring system. Peer-to-Peer Netw Appl 1–11Silva BM, Rodrigues JJ, Canelo F, Lopes IM, Lloret J (2014) Towards a cooperative security system for mobile-health applications. Electron Commer Re 1–27Flynn D, Gregory P, Makki H, Gabbay M (2009) Expectations and experiences of eHealth in primary care: a qualitative practice-based investigation. Int J Med Inform 78(9):588–604Thampi SM (2010) Survey of search and replication schemes in unstructured P2P networks. Netw Protoc Algoritm 2(1):93–131Khan SM, Mallesh N, Nambiar A, Wright M (2010) The dynamics of salsa: a robust structured P2P system. Netw Protoc Algoritm 2(4):40–60Garcia M, Hammoumi M, Canovas A, Lloret J (2011) Controlling P2P file-sharing networks’ traffic. Netw Protoc Algoritm 3(4):54–92Lloret J, Garcia M, Tomas J, Rodrigues JJPC (2014) Architecture and protocol for InterCloud communication. Inf Sci 258:434–451Chowdhury CR (2014) A survey of cloud based health care system. Int J Innov Res Comput Commun Eng 2(8):5477–5481Ghosh R, Papapanagiotou I, Boloor KA (2014) Survey on research initiatives for healthcare clouds. Cloud Computing Applications for Quality Health Care Delivery. IGI Global 1–18Donahue S (2010) Can cloud computing help fix health care? Cloudbook J 1(6):1–6Deng M, Petkovic M, Nalin M, Baroni IA (2011) Home healthcare system in the cloud--addressing security and privacy challenges. In proceedings of the 2011 I.E. International Conference on Cloud Computing (CLOUD 2011), Washington, pp 549–556Wang X, Gui Q, Liu B, Chen Y, Jin Z (2013) Leveraging mobile cloud for telemedicine: a performance study in medical monitoring. In proceedings of the 39th Annual Northeast Bioengineering Conference (NEBEC 2013), Syracuse, pp 49–50Alamri A (2012) Cloud-based e-health multimedia framework for heterogeneous network. In proceedings of the 2012 I.E. International Conference on Multimedia and Expo Workshops (ICMEW 2012), Melbourne, pp 447–452Constantinescu L, Kim J, Feng DD (2012) Sparkmed: a framework for dynamic integration of multimedia medical data into distributed m-health systems. IEEE Trans Inf Technol Biomed 16(1):40–52Botts N, Thoms B, Noamani A, Horan TA (2010) Cloud computing architectures for the underserved: public health cyberinfrastructures through a network of healthatms. In proceedings of the 43rd Hawaii International Conference on System Sciences (HICSS 2010), Honolulu, pp 1–10Fan L, Buchanan W, Thummler C, Lo O, Khedim A, Uthmani O, Lawson A, Bell D (2011) DACAR platform for eHealth services cloud. In proceedings of the 2011 I.E. International Conference on Cloud Computing (CLOUD 2011), Washington, pp 219–226Ruiz-Zafra A, Benghazi K, Noguera M, Garrido JL (2013) Zappa: An Open Mobile Platform to Build Cloud-Based m-Health Systems. In proceedings of the 4th International Symposium on Ambient Intelligence (ISAmI 2013), Salamanca, pp 87–94Nijon S, Dickerson RF, Asare P, Li Q, Hong D, Stankovic JA, Hu P, Shen G, Jiang X (2013) Auditeur: a mobile-cloud service platform for acoustic event detection on smartphones. In Proceeding of the 11th annual international conference on Mobile systems, applications, and services. ACM, Taipei, pp 403–416Lloret J, Diaz JR, Boronat F, Jiménez JM (2006) A fault-tolerant P2P-based protocol for logical networks interconnection. In proceedings of the International Conference on Networking and Services (ICNS’06), Silicon ValleyLloret J, Palau C, Boronat F, Tomas J (2008) Improving networks using group-based topologies. Comput Commun 31(14):3438–3450Lloret J, Boronat Segui F, Palau C, Esteve M (2005) Two levels SPF-based system to interconnect partially decentralized P2P file sharing networks. In proceedings of the Joint International Conference on Autonomic and Autonomous Systems and International Conference on Networking and Services.(ICAS-ICNS 2005), Papeete, p 39Cramer C, Kutzner K, Fuhrmann T (2004) Bootstrapping locality-aware P2P networkS. In proceedings of the 12th IEEE International Conference on Networks (ICON 2004), Singapore, pp 357–361FIPS 180-1 - Secure Hash Standard, SHA-1. National Institute of Standards and Technology. http://www.itl.nist.gov/fipspubs/fip180-1.htm [Last access: Dec. 30, 2014]Eastlake D., Jones P., US Secure Hash Algorithm 1 (SHA1),(2001). In IETF website, Available at: http://www.ietf.org/rfc/rfc3174.txt [Last access: March 20, 2015]Lacuesta R, Lloret J, Garcia M, Peñalver L (2011) Two secure and energy-saving spontaneous Ad-Hoc protocol for wireless mesh client networks. J Netw Comput Appl 3(2):492–50
Service composition based on SIP peer-to-peer networks
Today the telecommunication market is faced with the situation that customers are requesting for new telecommunication services, especially value added services. The concept of Next Generation Networks (NGN) seems to be a solution for this, so this concept finds its way into the telecommunication area. These customer expectations have emerged in the context of NGN and the associated migration of the telecommunication networks from traditional circuit-switched towards packet-switched networks.
One fundamental aspect of the NGN concept is to outsource the intelligence of services from the switching plane onto separated Service Delivery Platforms using SIP (Session Initiation Protocol) to provide the required signalling functionality. Caused by this migration process towards NGN SIP has appeared as the major signalling protocol for IP (Internet Protocol) based NGN. This will lead in contrast to ISDN (Integrated Services Digital Network) and IN (Intelligent Network) to significantly lower dependences among the network and services and enables to implement new services much easier and faster. In addition, further concepts from the IT (Information Technology) namely SOA (Service-Oriented Architecture) have largely influenced the telecommunication sector forced by amalgamation of IT and telecommunications. The benefit of applying SOA in telecommunication services is the acceleration of service creation and delivery. Main features of the SOA are that services are reusable, discoverable combinable and independently accessible from any location. Integration of those features offers a broader flexibility and efficiency for varying demands on services.
This thesis proposes a novel framework for service provisioning and composition in SIP-based peer-to-peer networks applying the principles of SOA. One key contribution of the framework is the approach to enable the provisioning and composition of services which is performed by applying SIP. Based on this, the framework provides a flexible and fast way to request the creation for composite services. Furthermore the framework enables to request and combine multimodal value-added services, which means that they are no longer limited regarding media types such as audio, video and text. The proposed framework has been validated by a prototype implementation
Video streaming over the internet using application layer multicast
Multicast is a very important communication paradigm. However, the deployment of multicast at IP layer is very slow, due to development and deployment issues such as ISPs' lack of incentives to update routers and inter-operability among multicast routing protocols. Application Layer Multicast (ALM) is a good alternative, where participating peers organize themselves into a logical overlay network atop the physical links and data is \tunneled" to each other via unicast links. The distinctive feature between IP multicast and ALM is that in ALM, data replication and forwarding functionalities are performed by participating peers (a.k.a. end systems), rather than the routers in Internet Protocol (IP) multicast. This fundamental difference enables ALM to be able to circumvent the development and deployment issues of IP multicast, by exploiting the resources (e.g., CPU cycles, storage, and access bandwidth) at the edge of the network. Nevertheless, it also raises other challenges, as peers are not as stable as routers since they may join and depart the on-going session at will. In this thesis, we address some of the challenges and they are summarized as follows: First, most current P2P or ALM streaming systems are equipped with a non-scalable membership management algorithm, greatly hindering their applicability to large-scale implementations over the Internet: they either rely on a central entity to handle group membership, or simply assume that all group members are visible to each other and flooding is the main mechanism used to disseminate membership-related updates to all participating group members. This implies that they are only applicable to small groups. Second, one of ALM's prominent features, flexility, has not been fully exploited: moving the multicast functionalities from lower layer (IP layer) to higher layer (Application layer) can greatly facilitate the integration of Quality-of-Service (QoS) support. The end-to-end philosophy states that it is better to leave those functionalities to higher layers because the heterogeneity among users' requirements can be handled much better by end users, rather than the network. However, QoS, and in particular, reliability has not been thoroughly addressed in existing ALM schemes. Third, admission control algorithms are essential to the success of any ALM system, due to the fact that in ALM, each peer acts as both a client as well as a server. On the other hand, the heterogeneity among peers, in terms of their computational power, storage capacity, and access bandwidth, further complicates the design of a good admission control. Several contributions are made to address the aforementioned research challenges, and they are outlined as follows: The first contribution is a devised gossip-based membership management algorithm that is able to collect and disseminate membership-related information under high rate of churn, using relatively low communication overheads. The second contribution is a reliability-centric multicast tree construction algorithm that greatly enhance peers' perceived reliability. The third contribution is a QoS-aware tree construction algorithm that accommodates the heterogeneity among peers, such as access bandwidth, network distance, and reliability. The last contribution is the identification of the admission control problem in this overlay video streaming
Design and Implementation of a Communication Protocol to Improve Multimedia QoS and QoE in Wireless Ad Hoc Networks
[EN] This dissertation addresses the problem of multimedia delivery over multi-hop ad hoc wireless networks, and especially over wireless sensor networks. Due to their characteristics of low power consumption, low processing capacity and low memory capacity, they have major difficulties in achieving optimal quality levels demanded by end users in such communications.
In the first part of this work, it has been carried out a study to determine the behavior of a variety of multimedia streams and how they are affected by the network conditions when they are transmitted over topologies formed by devices of different technologies in multi hop wireless ad hoc mode. To achieve this goal, we have performed experimental tests using a test bench, which combine the main codecs used in audio and video streaming over IP networks with different sound and video captures representing the characteristic patterns of multimedia services such as phone calls, video communications, IPTV and video on demand (VOD). With the information gathered in the laboratory, we have been able to establish the correlation between the induced changes in the physical and logical topology and the network parameters that measure the quality of service (QoS) of a multimedia transmission, such as latency, jitter or packet loss. At this stage of the investigation, a study was performed to determine the state of the art of the proposed protocols, algorithms, and practical implementations that have been explicitly developed to optimize the multimedia transmission over wireless ad hoc networks, especially in ad hoc networks using clusters of nodes distributed over a geographic area and wireless sensor networks.
Next step of this research was the development of an algorithm focused on the logical organization of clusters formed by nodes capable of adapting to the circumstances of real-time traffic. The stated goal was to achieve the maximum utilization of the resources offered by the set of nodes that forms the network, allowing simultaneously sending reliably and efficiently all types of content through them, and mixing conventional IP data traffic with multimedia traffic with stringent QoS and QoE requirements. Using the information gathered in the previous phase, we have developed a network architecture that improves overall network performance and multimedia streaming. In parallel, it has been designed and programmed a communication protocol that allows implementing the proposal and testing its operation on real network infrastructures.
In the last phase of this thesis we have focused our work on sending multimedia in wireless sensor networks (WSN). Based on the above results, we have adapted both the architecture and the communication protocol for this particular type of network, whose use has been growing hugely in recent years.[ES] Esta tesis doctoral aborda el problema de la distribuciĂłn de contenidos multimedia a travĂ©s de redes inalámbricas ad hoc multisalto, especialmente las redes inalámbricas de sensores que, debido a sus caracterĂsticas de bajo consumo energĂ©tico, baja capacidad de procesamiento y baja capacidad de memoria, plantean grandes dificultades para alcanzar los niveles de calidad Ăłptimos que exigen los usuarios finales en dicho tipo de comunicaciones.
En la primera parte de este trabajo se ha llevado a cabo un estudio para determinar el comportamiento de una gran variedad de flujos multimedia y como se ven afectados por las condiciones de la red cuando son transmitidos a travĂ©s topologĂas formadas por dispositivos de diferentes tecnologĂas que se comunican en modo ad hoc multisalto inalámbrico. Para ello, se han realizado pruebas experimentales sobre una maqueta de laboratorio, combinando los principales cĂłdecs empleados en la transmisiĂłn de audio y video a travĂ©s de redes IP con diversas capturas de sonido y video que representan patrones caracterĂsticos de servicios multimedia tales como las llamadas telefĂłnicas, videoconferencias, IPTV o video bajo demanda (VOD). Con la informaciĂłn reunida en el laboratorio se ha podido establecer la correlaciĂłn entre los cambios inducidos en la topologĂa fĂsica y lĂłgica de la red con los parámetros que miden la calidad de servicio (QoS) de una transmisiĂłn multimedia, tales como la latencia el jitter o la pĂ©rdida de paquetes. En esta fase de la investigaciĂłn se realiza un estudio para determinar el estado del arte de las propuestas de desarrollo e implementaciĂłn de protocolos y algoritmos que se han generado de forma explĂcita para optimizar la transmisiĂłn de tráfico multimedia sobre redes ad hoc inalámbricas, especialmente en las redes inalámbricas de sensores y redes ad hoc utilizando clĂşsteres de nodos distribuidos en un espacio geográfico.
El siguiente paso en la investigaciĂłn ha consistido en el desarrollo de un algoritmo propio para la organizaciĂłn lĂłgica de clĂşsteres formados por nodos capaces de adaptarse a las circunstancias del tráfico en tiempo real. El objetivo planteado es conseguir un aprovechamiento máximo de los recursos ofrecidos por el conjunto de nodos que forman la red, permitiendo de forma simultánea el envĂo de todo tipo de contenidos a travĂ©s de ellos de forma confiable y eficiente, permitiendo la convivencia de tráfico de datos IP convencional con tráfico multimedia con requisitos exigentes de QoS y QoE. A partir de la informaciĂłn conseguida en la fase anterior, se ha desarrollado una arquitectura de red que mejora el rendimiento general de la red y el de las transmisiones multimedia de audio y video en particular. De forma paralela, se ha diseñado y programado un protocolo de comunicaciĂłn que permite implementar el modelo y testear su funcionamiento sobre infraestructuras de red reales.
En la Ăşltima fase de esta tesis se ha dirigido la atenciĂłn hacia la transmisiĂłn multimedia en las redes de sensores inalámbricos (WSN). Partiendo de los resultados anteriores, se ha adaptado tanto la arquitectura como el protocolo de comunicaciones para este tipo concreto de red, cuyo uso se ha extendido en los Ăşltimos años de forma considerable[CA] Esta tesi doctoral aborda el problema de la distribuciĂł de continguts multimèdia a travĂ©s de xarxes sense fil ad hoc multi salt, especialment les xarxes sense fil de sensors que, a causa de les seues caracterĂstiques de baix consum energètic, baixa capacitat de processament i baixa capacitat de memòria, plantegen grans dificultats per a aconseguir els nivells de qualitat òptims que exigixen els usuaris finals en eixos tipus de comunicacions.
En la primera part d'este treball s'ha dut a terme un estudi per a determinar el comportament d'una gran varietat de fluxos multimèdia i com es veuen afectats per les condicions de la xarxa quan sĂłn transmesos a travĂ©s topologies formades per dispositius de diferents tecnologies que es comuniquen en mode ad hoc multi salt sense fil. Per a això, s'han realitzat proves experimentals sobre una maqueta de laboratori, combinant els principals cĂłdecs empleats en la transmissiĂł d'Ă udio i vĂdeo a travĂ©s de xarxes IP amb diverses captures de so i vĂdeo que representen patrons caracterĂstics de serveis multimèdia com son les cridades telefòniques, videoconferències, IPTV o vĂdeo baix demanda (VOD). Amb la informaciĂł reunida en el laboratori s'ha pogut establir la correlaciĂł entre els canvis induĂŻts en la topologia fĂsica i lògica de la xarxa amb els parĂ metres que mesuren la qualitat de servei (QoS) d'una transmissiĂł multimèdia, com la latència el jitter o la pèrdua de paquets. En esta fase de la investigaciĂł es realitza un estudi per a determinar l'estat de l'art de les propostes de desenvolupament i implementaciĂł de protocols i algoritmes que s'han generat de forma explĂcita per a optimitzar la transmissiĂł de trĂ fic multimèdia sobre xarxes ad hoc sense fil, especialment en les xarxes sense fil de sensors and xarxes ad hoc utilitzant clusters de nodes distribuĂŻts en un espai geogrĂ fic.
El segĂĽent pas en la investigaciĂł ha consistit en el desenvolupament d'un algoritme propi per a l'organitzaciĂł lògica de clusters formats per nodes capaços d'adaptar-se a les circumstĂ ncies del trĂ fic en temps real. L'objectiu plantejat Ă©s aconseguir un aprofitament mĂ xim dels recursos oferits pel conjunt de nodes que formen la xarxa, permetent de forma simultĂ nia l'enviament de qualsevol tipus de continguts a travĂ©s d'ells de forma confiable i eficient, permetent la convivència de trĂ fic de dades IP convencional amb trĂ fic multimèdia amb requisits exigents de QoS i QoE. A partir de la informaciĂł aconseguida en la fase anterior, s'ha desenvolupat una arquitectura de xarxa que millora el rendiment general de la xarxa i el de les transmissions multimèdia d'Ă udio i vĂdeo en particular. De forma paralÂżlela, s'ha dissenyat i programat un protocol de comunicaciĂł que permet implementar el model i testejar el seu funcionament sobre infraestructures de xarxa reals.
En l'Ăşltima fase d'esta tesi s'ha dirigit l'atenciĂł cap a la transmissiĂł multimèdia en les xarxes de sensors sense fil (WSN). Partint dels resultats anteriors, s'ha adaptat tant l'arquitectura com el protocol de comunicacions per a aquest tipus concret de xarxa, l'Ăşs del qual s'ha estĂ©s en els Ăşltims anys de forma considerable.DĂaz Santos, JR. (2016). Design and Implementation of a Communication Protocol to Improve
Multimedia QoS and QoE in Wireless Ad Hoc Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62162TESI
Towards automatic traffic classification and estimation for available bandwidth in IP networks.
Growing rapidly, today's Internet is becoming more difficult to manage. A good understanding of what kind of network traffic classes are consuming network resource as well as how much network resource is available is important for many management tasks like QoS provisioning and traffic engineering. In the light of these objectives, two measurement mechanisms have been explored in this thesis. This thesis explores a new type of traffic classification scheme with automatic and accurate identification capability. First of all, the novel concept of IP flow profile, a unique identifier to the associated traffic class, has been proposed and the relevant model using five IP header based contexts has been presented. Then, this thesis shows that the key statistical features of each context, in the IP flow profile, follows a Gaussian distribution and explores how to use Kohonen Neural Network (KNN) for the purpose of automatically producing IP flow profile map. In order to improve the classification accuracy, this thesis investigates and evaluates the use of PCA for feature selection, which enables the produced patterns to be as tight as possible since tight patterns lead to less overlaps among patterns. In addition, the use of Linear Discriminant Analysis and alternative KNN maps has been investigated as to deal with the overlap issue between produced patterns. The entirety of this process represents a novel addition to the quest for automatic traffic classification in IP networks. This thesis also develops a fast available bandwidth measurement scheme. It firstly addresses the dynamic problem for the one way delay (OWD) trend detection. To deal with this issue, a novel model - asymptotic OWD Comparison (AOC) model for the OWD trend detection has been proposed. Then, three statistical metrics SOT (Sum of Trend), PTC (Positive Trend Checking) and CTC (Complete Trend Comparison) have been proposed to develop the AOC algorithms. To validate the proposed AOC model, an avail-bw estimation tool called Pathpair has been developed and evaluated in the Planetlah environment
Towards a cloud enabler : from an optical network resource provisioning system to a generalized architecture for dynamic infrastructure services provisioning
This work was developed during a period where most of the optical management and provisioning system where manual and proprietary. This work contributed to the evolution of the state of the art of optical networks with new architectures and advanced virtual infrastructure services. The evolution of optical networks, and internet globally, have been very promising during the last decade. The impact of mobile technology, grid, cloud computing, HDTV, augmented reality and big data, among many others, have driven the evolution of optical networks towards current service technologies, mostly based on SDN (Software Defined Networking) architectures and NFV(Network Functions Virtualisation). Moreover, the convergence of IP/Optical networks and IT services, and the evolution of the internet and optical infrastructures, have generated novel service orchestrators and open source frameworks. In fact, technology has evolved that fast that none could foresee how important Internet is for our current lives. Said in other words, technology was forced to evolve in a way that network architectures became much more transparent, dynamic and flexible to the end users (applications, user interfaces or simple APIs).
This Thesis exposes the work done on defining new architectures for Service Oriented Networks and the contribution to the state of the art. The research work is divided into three topics. It describes the evolution from a Network Resource Provisioning System to an advanced Service Plane, and ends with a new architecture that virtualized the optical infrastructure in order to provide coordinated, on-demand and dynamic services between the application and the network infrastructure layer, becoming an enabler for the new generation of cloud network infrastructures.
The work done on defining a Network Resource Provisioning System established the first bases for future work on network infrastructure virtualization. The UCLP (User Light Path Provisioning) technology was the first attempt for Customer Empowered Networks and Articulated Private Networks. It empowered the users and brought virtualization and partitioning functionalities into the optical data plane, with new interfaces for dynamic service provisioning. The work done within the development of a new Service Plane allowed the provisioning of on-demand connectivity services from the application, and in a multi-domain and multi-technology scenario based on a virtual network infrastructure composed of resources from different infrastructure providers. This Service Plane facilitated the deployment of applications consuming large amounts of data under deterministic conditions, so allowing the networks behave as a Grid-class resource. It became the first on-demand provisioning system that at lower levels allowed the creation of one virtual domain composed from resources of different providers.
The last research topic presents an architecture that consolidated the work done in virtualisation while enhancing the capabilities to upper layers, so fully integrating the optical network infrastructure into the cloud environment, and so providing an architecture that enabled cloud services by integrating the request of optical network and IT infrastructure services together at the same level. It set up a new trend into the research community and evolved towards the technology we use today based on SDN and NFV.
Summing up, the work presented is focused on the provisioning of virtual infrastructures from the architectural point of view of optical networks and IT infrastructures, together with the design and definition of novel service layers. It means, architectures that enabled the creation of virtual infrastructures composed of optical networks and IT resources, isolated and provisioned on-demand and in advance with infrastructure re-planning functionalities, and a new set of interfaces to open up those services to applications or third parties.Aquesta tesi es va desenvolupar durant un perĂode on la majoria de sistemes de gestiĂł de xarxa òptica eren manuals i basats en sistemes propietaris. En aquest sentit, la feina presentada va contribuir a l'evoluciĂł de l'estat de l'art de les xarxes òptiques tant a nivell d’arquitectures com de provisiĂł d’infraestructures virtuals. L'evoluciĂł de les xarxes òptiques, i d'Internet a nivell mundial, han estat molt prometedores durant l'Ăşltima dècada. L'impacte de la tecnologia mòbil, la computaciĂł al nĂşvol, la televisiĂł d'alta definiciĂł, la realitat augmentada i el big data, entre molts altres, han impulsat l'evoluciĂł cap a xarxes d’altes prestacions amb nous serveis basats en SDN (Software Defined Networking) i NFV (Funcions de xarxa La virtualitzaciĂł). D'altra banda, la convergència de xarxes òptiques i els serveis IT, junt amb l'evoluciĂł d'Internet i de les infraestructures òptiques, han generat nous orquestradors de serveis i frameworks basats en codi obert. La tecnologia ha evolucionat a una velocitat on ningĂş podria haver predit la importĂ ncia que Internet estĂ tenint en el nostre dia a dia. Dit en altres paraules, la tecnologia es va veure obligada a evolucionar d'una manera on les arquitectures de xarxa es fessin mĂ©s transparent, dinĂ miques i flexibles vers als usuaris finals (aplicacions, interfĂcies d'usuari o APIs simples). Aquesta Tesi presenta noves arquitectures de xarxa òptica orientades a serveis. El treball de recerca es divideix en tres temes. Es presenta un sistema de virtualitzaciĂł i aprovisionament de recursos de xarxa i la seva evoluciĂł a un pla de servei avançat, per acabar presentant el disseny d’una nova arquitectura capaç de virtualitzar la infraestructura òptica i IT i proporcionar serveis de forma coordinada, i sota demanda, entre l'aplicaciĂł i la capa d'infraestructura de xarxa òptica. Tot esdevenint un facilitador per a la nova generaciĂł d'infraestructures de xarxa en el nĂşvol. El treball realitzat en la definiciĂł del sistema de virtualitzaciĂł de recursos va establir les primeres bases sobre la virtualitzaciĂł de la infraestructura de xarxa òptica en el marc de les “Customer Empowered Networks” i “Articulated Private Networks”. Amb l’objectiu de virtualitzar el pla de dades òptic, i oferir noves interfĂcies per a la provisiĂł de serveis dinĂ mics de xarxa. En quant al pla de serveis presentat, aquest va facilitat la provisiĂł de serveis de connectivitat sota demanda per part de l'aplicaciĂł, tant en entorns multi-domini, com en entorns amb mĂşltiples tecnologies. Aquest pla de servei, anomenat Harmony, va facilitar el desplegament de noves aplicacions que consumien grans quantitats de dades en condicions deterministes. En aquest sentit, va permetre que les xarxes es comportessin com un recurs Grid, i per tant, va esdevenir el primer sistema d'aprovisionament sota demanda que permetia la creaciĂł de dominis virtuals de xarxa composts a partir de recursos de diferents proveĂŻdors. Finalment, es presenta l’evoluciĂł d’un pla de servei cap una arquitectura global que consolida el treball realitzat a nivell de convergència d’infraestructures (òptica + IT) i millora les capacitats de les capes superiors. Aquesta arquitectura va facilitar la plena integraciĂł de la infraestructura de xarxa òptica a l'entorn del nĂşvol. En aquest sentit, aquest resultats van evolucionar cap a les tendències actuals de SDN i NFV. En resum, el treball presentat es centra en la provisiĂł d'infraestructures virtuals des del punt de vista d’arquitectures de xarxa òptiques i les infraestructures IT, juntament amb el disseny i definiciĂł de nous serveis de xarxa avançats, tal i com ho va ser el servei de re-planificaciĂł dinĂ micaPostprint (published version
Computer-network Solutions for Pervasive Computing
Lo scenario delle reti di comunicazione di tipo wireless sta rapidamente evolvendo verso i sistemi pervasivi in cui i dispositivi wireless, di diversi tipi e grandezze, costituiscono parte integrante dell’ambiente in cui sono immersi, ed interagiscono continuamente ed in maniera trasparente con gli utenti che vi vivono o che lo attraversano. Si parla a tal proposito anche di ambienti intelligenti. Seguendo l’evoluzione dai sistemi mobili a quelli pervasivi, questa tesi rivisita diversi tipi di ambienti wireless che si sono sviluppati e diffusi negli ultimi 20 anni: a partire dalle wireless LANs, proseguendo con le reti ad hoc, per finire con le reti opportunistiche. Sebbene molte problematiche delle reti wireless si ripropongano in quasi tutti gli scenari (ad esempio il risparmio energetico), a scenari wireless diversi corrispondono in genere utilizzi differenti e diversi fabbisogni degli utenti, come pure problemi specifici che richiedono soluzioni dedicate. Alcune soluzioni specifiche sono analizzate e proposte in questa tesi. Le reti WLANs basate su infrastruttura sono usate generalmente per fornire accesso alla rete Internet ed infatti lo scenario che le comprende è solitamente riferito come Wireless Internet. Nonostante la presenza dell’infrastruttuta fissa garantisca in generale una trasmissione di dati affidabile, l’utilizzo di questo tipo di reti per fornire esattamente gli stessi tipi di servizi delle reti fisse provoca un elevato consumo di risorse che all’interno delle WLANs sono invece limitate. Inoltre l’utilizzo dei protocolli dello stack TCP/IP sui link wireless è di solito fonte di inefficienze viste le profonde differenze esistenti fra i link wireless e quelli fissi. La progettazione di servizi in uno scenario di wireless Internet ha come primario obiettivo quello di garantire la fruizione da parte degli utenti mobili senza soluzione di continuità , mascherando così la presenza del link wireless che ha banda nominale inferiore rispetto ai link fissi ed è soggetto a maggiori perdite, e supportando la mobilità degli utenti all’interno delle zone di copertura (handoff). La gestione dei servizi di wireless Internet deve sempre essere integrata con soluzioni di risparmio energetico tese ad allungare il più possibile l’autonomia energetica dei dispositivi degli utenti (alimentati a batteria) garantendo così loro un servizio duraturo nel tempo. Abbiamo studiato una soluzione per servizi di streaming audio-video verso terminali mobili in un ambiente di wireless LAN. Oltre a garantire la continuità della riproduzione multimediale con buona qualità , questa soluzione ottimizza il consumo energetico del terminale wireless agendo sulla scheda di rete wireless. Durante lo streaming infatti, la scheda di rete viene periodicamente messa in uno stato a basso consumo energetico (sleep). I periodi di sleep della scheda vengono calcolati adattivamente in funzione dello stato di avanzamento della riproduzione multimediale e della banda disponibile istantaneamente sul canale wireless opportunamente monitorato. Il riposo della scheda di rete non incide sul processo di riproduzione e quindi sulla qualità del servizio percepita dall’utente mobile.
A differenza delle WLANs, le reti MANETs sono prive di infrastruttura fissa ed i nodi che vi partecipano si autoconfigurano ed autoorganizzano tra di loro. Le MANETs si mostrano particolarmente adatte ad esigenze temporanee di gruppi di utenti che vogliano condividere dati, scambiarsi messaggi, o altro. Uno dei principali interessi di ricerca nell’ambito delle reti MANETs ha riguardato storicamente lo studio dei protocolli di routing per l’instradamento delle informazioni fra nodi sorgente e nodi destinatari. In una rete MANET infatti, vista l’assenza di infrastruttura, ogni nodo è coinvolto nella funzione di instradamento. Negli ultimi anni tuttavia, un nuovo aspetto di ricerca sta acquistando sempre maggiore attenzione e riguarda la sperimentazione su testbed reali. Le poche esperienze sperimentali eseguite su MANETs hanno dimostrato l’inadeguatezza degli studi di tipo analitico-simulativo nel giudicare l’efficacia delle soluzioni progettate per reti MANETs. Questo è principalmente dovuto al fatto che gli scenari wireless sono estremamente complessi e soggetti a fenomeni di diversa natura che influiscono sulle comunicazioni ma che sono difficilmente condensabili in un modello analitico completo. I modelli esistenti nei simulatori attualmente diffusi sono spesso causa di errori nel validare o al contrario bocciare le soluzioni ed i protocolli testati. Le attività di sperimentazione su testbed reali hanno dunque un duplice scopo: i) validare protocolli e soluzioni proposte attualmente, e ii) gettare le basi per la costruizione di nuovi modelli analitici e simulativi che siano maggiormente attendibili di quelli attuali. L’esperienza condotta su di un testbed reale per reti ad hoc comprendente portatili e palmari fino ad un totale di 12 nodi, ha dimostrato l’efficacia delle implementazioni di due protocolli di routing: AODV (Ad hoc On demand Distance Vector) ed OLSR (Optimized Link State Routing). Tuttavia, benchè entrambi siano funzionalmente corretti, mostrano comportamenti differenti quando usati per supportare servizi di livello middleware ed applicativi (vedi ad esempio file sharing o trasferimenti ftp). In particolare, i ritardi causati dalla scoperta delle rotte in AODV sono spesso causa di inefficienze o addirittura di interruzione del servizio. OLSR invece, seppure responsabile di un overhead di traffico maggiore, si mostra maggiormente adatto alle interazioni con i servizi dei livelli superiori. Infine, l’esperienza ha dimostrato la necessità di ripensare molti dei servizi disponibili su rete fissa per adeguarli alle caratteristiche delle reti wireless e particolarmente di quelle ad hoc.
Una nuova tipologia di reti wireless sta emergendo attualmente e si sta rivelando di particolare interesse: quella delle reti opportunistiche. Le reti opportunistiche non si appoggiano su alcuna infrastruttura fissa, né cercano di autoconfigurarsi in una infrastruttura wireless temporanea costituita da nodi vicini. Sfruttano le opportunità di contatto che si verificano fra i nodi (dispositivi wireless di piccola taglia) trasportati dagli utenti nelle loro attività quotidiane (ad esempio a lavoro, sugli autobus, a scuola o all’università , ecc.). I messaggi sono scambiati ogni qualvolta si renda possibile, ovunque sia possibile ed il successo della loro trasmissione è strettamente legato alle dinamiche sociali in cui sono coinvolti gli utenti che trasportano i dispositivi ed alla storia degli incontri tra individui. Data la mobilità estremamente elevata che caratterizza questo nuovo scenario di reti, e la nota rumorosità delle comunicazioni wireless, l’affidabilità delle trasmissioni emerge come uno dei fattori di principale interesse. Infatti, le comunicazioni possono aver luogo soltanto durante i periodi di contatto tra i nodi e devono essere estremamente veloci ed efficaci. Questo porta a dover fare uno sforzo di progettazione per nuovi protocolli di comunicazione che si diversifichino da quelli oggi più diffusi e basati sulla ritrasmissione dei dati mancanti. Le ritrasmissioni infatti, nella maggior parte dei casi potrebbero non poter essere eseguite per mancanza di tempo. Una strategia valida per gestire l’affidabilità delle comunicazioni opportunistiche in simili scenari estremi (caratterizzati cioè da scarse risorse e scarsa connettività ) prevede l’utilizzo combinato di tecniche di codifica dei dati e strategie di instradamento di tipo epidemico. Questo approccio sfrutta la ridondanza sia delle informazioni, sia dei percorsi. La ridondanza delle informazioni dà robustezza a fronte della perdita dei dati in rete poiché è necessario che soltanto un sottoinsieme dei codici generati arrivi a destinazione per consentire al ricostruzione corretta delle informazioni. La ridondanza dei percorsi invece è necessaria poichè non è possibile predirre in anticipo la sequenza dei contatti che può portare i dati a destinazione e pertanto è necessario distribuire l’informazione in più direzioni. Le reti opportunistiche caratterizzate dalla presenza di dispositivi con limitata autonomia energetica e risorse limitate, offrono attualmente lo scenario che meglio traduce il concetto di sistemi pervasivi. Di particolare interesse è il caso delle reti di sensori sparse in cui i sensori sono disposti nell’ambiente con funzione di monitoraggio ed i dati che collezionano vengono raccolti da degli agenti mobili che passano nelle vicinanze e che sono noti come data MULEs. I data MULEs possono utilizzare le informazioni acquisite dai sensori per eseguire applicazioni dipendenti dal contesto o possono semplicemente inoltrarle fino a quando raggiungono l’infrastruttura dove vengono elaborati e memorizzati. Le interazioni fra i sensori immersi nell’ambiente ed i data MULEs sono soltanto un primo passo di un sistema di comunicazione globale completamente opportunistico in cui i data MULEs scambiano l’un l’altro le informazioni che trasportano fino a quando infine, i dati pervengono alle destinazioni più lontane. In questo scenario, le comunicazioni wireless completano naturalmente le interazioni fra gli utenti e si verificano ogni qualvolta gli utenti si incontrano oppure si avvicinano casualmente l’un l’altro, dovunque questa interazione avvenga. Per supportare un simile framework, è necessario sviluppare nuovi paradigmi di comunicazione che tengano in considerazione l’assenza di link stabili tra i nodi che comunicano (connettività intermittente) e che assumano quindi la disponibilità di brevi periodi di contatto per comunicare. Inoltre i nuovi paradigmi di comunicazione devono generalmente assumere l’assenza di un percorso completo fra i nodi sorgente e destinatario e sfruttare invece forme di instradamento delle informazioni che sono simili al modo in cui avvengono le interazioni sociali fra le persone. Strategie di instradamento basate su codifica dei dati offrono una valida soluzione per supportare il framework emergente dei sistemi pervasivi