@article {Longo2015280, title = {Dependability modeling of Software Defined Networking}, journal = {Computer Networks}, volume = {83}, year = {2015}, note = {cited By 6}, pages = {280-296}, publisher = {Elsevier}, abstract = {

Software Defined Networking (SDN) is a new network design paradigm that aims at simplifying the implementation of complex networking infrastructures by separating the forwarding functionalities (data plane) from the network logical control (control plane). Network devices are used only for forwarding, while decisions about where data is sent are taken by a logically centralized yet physically distributed component, i.e., the SDN controller. From a quality of service (QoS) point of view, an SDN controller is a complex system whose operation can be highly dependent on a variety of parameters, e.g., its degree of distribution, the corresponding topology, the number of network devices to control, and so on. Dependability aspects are particularly critical in this context. In this work, we present a new analytical modeling technique that allows us to represent an SDN controller whose components are organized in a hierarchical topology, focusing on reliability and availability aspects and overcoming issues and limitations of Markovian models. In particular, our approach allows to capture changes in the operating conditions (e.g., in the number of managed devices) still allowing to represent the underlying phenomena through generally distributed events. The dependability of a use case on a two-layer hierarchical SDN control plane is investigated through the proposed technique providing numerical results to demonstrate the feasibility of the approach. {\textcopyright} 2015 Elsevier B.V.

}, keywords = {Availability, Complex networks, Controllers, Degree of distributions, Distributed components, Electric network topology, Information dissemination, Markov processes, Networking infrastructure, Non-Markovian, Quality control, Quality of service, Random processes, Reliability, Reliability and availability, Software defined networking (SDN), Software reliability, Software-defined networkings, Stochastic models, Stochastic systems, Topology, Type expansions}, issn = {13891286}, doi = {10.1016/j.comnet.2015.03.018}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946489290\&doi=10.1016\%2fj.comnet.2015.03.018\&partnerID=40\&md5=b4f32c89d2b7b79fefcaf97082764960}, author = {Francesco Longo and Salvatore Distefano and Dario Bruneo and Marco Scarpa} } @proceedings {Bruneo201598, title = {An SRN-based resiliency quantification approach}, journal = {Proceedings of the 36th International Conference on Application and Theory of Petri Nets and Concurrency (Petri Nets)}, volume = {9115 Lecture Notes in Computer Science}, year = {2015}, note = {cited By 0; Conference of 36th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2015 ; Conference Date: 21 June 2015 Through 26 June 2015; Conference Code:119609}, pages = {98-116}, publisher = {Springer Verlag}, address = {Brussels, Belgium, 21-26 June 2015}, abstract = {

Resiliency is often considered as a synonym for faulttolerance and reliability/availability. We start from a different definition of resiliency as the ability to deliver services when encountering unexpected changes. Semantics of change is of extreme importance in order to accurately capture the real behavior of a system. We propose a resiliency analysis technique based on stochastic reward nets that allows the modeler: (1) to reuse an already existing dependability or performance model for a specific system with minimal modifications, and (2) to adapt the given model for specific change semantics. To automate the model analysis an algorithm is designed and the modeler is provided with a formalism that corresponds to the semantics. Our algorithm and approach is implemented to demonstrate the proposed resiliency quantification approach. Finally, we discuss the differences between our approach and an alternative technique based on deterministic and stochastic Petri nets and highlight the advantages of the proposed approach in terms of semantics specification. {\textcopyright} Springer International Publishing Switzerland 2015.

}, keywords = {Analysis techniques, Deterministic and stochastic Petri nets, Model analysis, Performance Model, Petri nets, Resiliency, Semantics, Stochastic models, Stochastic reward nets, Stochastic systems}, isbn = {9783319194875}, issn = {03029743}, doi = {10.1007/978-3-319-19488-2_5}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84937428490\&partnerID=40\&md5=7d0bbe99afba1a79df65b4e35e86a02c}, author = {Dario Bruneo and Francesco Longo and Marco Scarpa and Antonio Puliafito and Rahul Ghosh and Kishor S. Trivedi} } @article {Bruneo2013279, title = {Analytical investigation of availability in a vision cloud storage cluster}, journal = {Scalable Computing - SCPE}, volume = {14}, number = {4}, year = {2013}, note = {cited By 2}, pages = {279-290}, abstract = {

The goal of VISION Cloud, a European Commission funded project, is to design a new scalable and flexible storage cloud architecture able to provide data-intensive storage cloud services. The proposed environment employs a distributed file system on top of a set of storage rich nodes composing a cluster. Several clusters constitute a data center, while multiple geographically distributed data centers form a single storage cloud. In this paper, we focus on a single VISION Cloud storage cluster, providing a stochastic reward net model for an investigation of its availability. The proposed model is a first attempt at obtaining a quantification of the availability level of the cloud storage provided by the VISION Cloud architecture. {\textcopyright} 2013 SCPE.

}, keywords = {Analytical investigations, cloud architectures, Data intensive, Digital storage, Distributed data, Distributed file systems, European Commission, Flexible storage, Stochastic models, Stochastic reward nets}, issn = {18951767}, doi = {10.12694/scpe.v14i4.933}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84893439215\&partnerID=40\&md5=cd97e97b8741a1e968a6bf8e20271ff8}, author = {Dario Bruneo and Francesco Longo and David Hadas and Elliot K. Kolodner} } @proceedings {Bruneo201371, title = {Availability Assessment of a Vision Cloud Storage Cluster}, journal = {European Conference on Service-Oriented and Cloud Computing (ESOCC)}, volume = {393 Communications in Computer and Information Science}, year = {2013}, note = {cited By 0; Conference of European Conference on Service-Oriented and Cloud Computing, ESOCC 2013 ; Conference Date: 11 September 2013 Through 13 September 2013; Conference Code:106555}, pages = {71-82}, publisher = {Springer Verlag}, address = {Malaga, Spain, 11-13 September 2013}, abstract = {

VISION Cloud is a European Commission funded project, whose aim is to design and propose a new architecture for a scalable and flexible cloud environment. The VISION Cloud reference architecture considers a single cloud as composed by multiple distributed data centers each of which can be composed by a great number of storage clusters. On top of the storage rich nodes forming each cluster, a distributed file system is built. In this paper, we provide an stochastic reward net model for a storage cluster in the context of the storage cloud environment proposed by the VISION Cloud project. The proposed model represents a first step in the direction of obtaining a quantification of the availability level reached through the use of the VISION Cloud proposed architecture from a user perspective. {\textcopyright} Springer-Verlag Berlin Heidelberg 2013.

}, keywords = {Architecture, Availability assessment, cloud computing, Cloud environments, Distributed file systems, European Commission, Proposed architectures, Reference architecture, Stochastic models, Stochastic reward nets, Stochastic systems, User perspectives}, isbn = {9783642453632}, issn = {18650929}, doi = {10.1007/978-3-642-45364-9_7}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-84904676242\&partnerID=40\&md5=d7510b50bf986e126b22270279202382}, author = {Dario Bruneo and Francesco Longo and David Hadas and Hillel Kolodner} } @proceedings {Bruneo2010243, title = {VO-level performance analysis of gLite Grids}, journal = {Proceedings of the 19th IEEE Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE)}, year = {2010}, note = {cited By 0; Conference of 19th IEEE International Workshops on Enabling Technologies: Infrastructure for Collaborative Enterprises, WETICE 2010 ; Conference Date: 28 June 2010 Through 30 June 2010; Conference Code:81490}, pages = {243-248}, publisher = {IEEE Computer Society}, address = {Larissa, Greece, 28-30 June 2010}, abstract = {

Business oriented grids call for effective Quality of Service strategies able to adapt to different user requirements. Performance analyses and predictions with respect to different load conditions or management policies are essential instruments to define such strategies. In this paper, we present a non-Markovian Stochastic Petri Net model that allows to conduct performance analyses of Grid systems focusing on aspects related to the Virtual Organization as a whole. Different job allocation techniques will be evaluated with respect to both user and provider point-of-views. We will also investigate the influence of different information update policies on the accuracy of the allocation schemes, highlighting the costs/benefits in terms of job waiting time, service availability, and system utilization. {\textcopyright} 2010 IEEE.

}, keywords = {Business-oriented, gLite middleware, Graph theory, Grid computing, Grid systems, Information updates, Job allocation, Load condition, Management policy, middleware, Non-Markovian, Performance analysis, performance measurements, Petri nets, Quality of service, Random access storage, Service availability, Stochastic models, Stochastic Petri Nets, Stochastic systems, System utilization, User requirements, Virtual organization, Waiting-time}, isbn = {9780769540634}, issn = {15244547}, doi = {10.1109/WETICE.2010.45}, url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-77955917215\&partnerID=40\&md5=5f89b9d07327325a09d78d1af77f0519}, author = {Dario Bruneo and Francesco Longo and Marco Scarpa and Antonio Puliafito} }