72 results on '"Kentis, A"'
Search Results
2. Accelerating Platform Deployments in the Cloud: A Qualitative Assessment Based on CORD.
- Author
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Angelos Mimidis Kentis, José Soler, Adam Broadbent, and Paul Veitch
- Published
- 2020
- Full Text
- View/download PDF
3. A Systematic Review of Sleep Disturbance in Idiopathic Intracranial Hypertension.
- Author
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Kentis, Sabrina, Shaw, Jacob S., Richey, Lisa N., Young, Lisa, Kosyakova, Natalia, Bryant, Barry R., Esagoff, Aaron I., Buenaver, Luis F., Salas, Rachel Marie E., and Peters, Matthew E.
- Published
- 2025
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- View/download PDF
4. Assessing the Patient-Facing ASTHMAXcel Mobile Application Through the Health IT Evaluation Framework
- Author
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Kentis, Sabrina, primary, Thomas, Sherron, additional, and Jariwala, Sunit, additional
- Published
- 2024
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- View/download PDF
5. Evaluating the ASTHMAXcel Mobile Application's Implementation Within Primary Care Settings Through the RE-AIM Framework
- Author
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Thomas, Sherron, primary, Kentis, Sabrina, additional, and Jariwala, Sunit, additional
- Published
- 2024
- Full Text
- View/download PDF
6. A Novel Algorithm for Flow-Rule Placement in SDN Switches.
- Author
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Angelos Mimidis Kentis, Artur Pilimon, José Soler, Michael S. Berger, and Sarah Ruepp
- Published
- 2018
- Full Text
- View/download PDF
7. Analysis of traffic engineering capabilities for SDN-based data center networks.
- Author
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Artur Pilimon, Angelos Mimidis Kentis, Sarah Ruepp, and Lars Dittmann
- Published
- 2018
- Full Text
- View/download PDF
8. A systematic review of pre-injury anxiety disorder and post-concussion outcomes in youth and young adult athletes.
- Author
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Huang, Philip C., Shaw, Jacob S., Kentis, Sabrina, Young, Lisa, Bryant, Barry R., Esagoff, Aaron I., White, Jacob, and Peters, Matthew E.
- Subjects
MEDICAL information storage & retrieval systems ,SPORTS injuries ,ANXIETY ,SYSTEMATIC reviews ,MEDLINE ,LONGITUDINAL method ,CONVALESCENCE ,BRAIN concussion ,TIME ,PSYCHOLOGY information storage & retrieval systems ,SYMPTOMS ,ADOLESCENCE ,CHILDREN ,ADULTS - Abstract
Pre-injury anxiety disorder may be a risk factor for poor outcomes following sportsrelated concussion. A systematic review was performed to characterize the relationship between pre-injury anxiety disorder and post-concussion symptom presentation and recovery time after sports-related concussions among children, adolescents, and young adults. A PRISMA-compliant literature search was conducted in Ovid MEDLINE, PsycINFO, EMBASE, and Scopus for articles published up to 25 January 2024. The initial query yielded 1358 unique articles. Articles that analyzed the relationship between pre-injury anxiety disorder and post-concussion symptoms and recovery time were included. A final cohort of 11 articles was extracted, comprising a total of 8390 study participants, of whom 921 had a history of pre-injury anxiety disorder. Pre-injury anxiety disorder was associated with prolonged time to return to sports activity and an increased incidence of physical, emotional, cognitive, and sleep-related symptoms. While the results of this review suggest an association between pre-injury anxiety disorder and post-concussion symptoms and recovery time, future studies should be more stringent regarding standardized anxiety disorder definitions, longitudinal assessment of post-concussion symptoms, anxiety disorder subtypes, and anxiety treatment history. [ABSTRACT FROM AUTHOR]
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- 2024
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9. A brain atlas for the camouflaging dwarf cuttlefish, Sepia bandensis
- Author
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Montague, Tessa G., primary, Rieth, Isabelle J., additional, Gjerswold-Selleck, Sabrina, additional, Garcia-Rosales, Daniella, additional, Aneja, Sukanya, additional, Elkis, Dana, additional, Zhu, Nanyan, additional, Kentis, Sabrina, additional, Rubino, Frederick A., additional, Nemes, Adriana, additional, Wang, Katherine, additional, Hammond, Luke A., additional, Emiliano, Roselis, additional, Ober, Rebecca A., additional, Guo, Jia, additional, and Axel, Richard, additional
- Published
- 2023
- Full Text
- View/download PDF
10. Effects of port congestion in the gate control list scheduling of time sensitive networks.
- Author
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Angelos Mimidis Kentis, Michael Stübert Berger, and José Soler
- Published
- 2017
- Full Text
- View/download PDF
11. Demonstrating carbon dioxide capture through pilot plant operation
- Author
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ICWES (15th : 2011 : Adelaide, S.A.), Anderson, Clare J, Mumford, Kathryn A, Smith, Kathryn H, Kentis, Sandra E, Qader, Abdul, and Stevens, Geoff W
- Published
- 2011
12. The Next Generation Platform as A Service: Composition and Deployment of Platforms and Services.
- Author
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Angelos Mimidis Kentis, José Soler, Paul Veitch, Adam Broadbent, Marco Mobilio, Oliviero Riganelli, Steven van Rossem, Wouter Tavernier, and Bessem Sayadi
- Published
- 2019
- Full Text
- View/download PDF
13. Artworks for Jellyfish and Other Others
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Amanda Boetzkes, Ted Hiebert, Julian A M.P., bug carlson, Nicole Clouston, Silas Fischer, Terrance Houle, Cavil S. Kentis, Jessica Jacobson-Konefall, Ryuta Nakajima, Sky O’Brien, Amanda White, Amanda Boetzkes, Ted Hiebert, Julian A M.P., bug carlson, Nicole Clouston, Silas Fischer, Terrance Houle, Cavil S. Kentis, Jessica Jacobson-Konefall, Ryuta Nakajima, Sky O’Brien, and Amanda White
- Abstract
After humans destroy one another’s worlds, what will be left are the jellyfish. At least, this is the suggestion of the biologist Jeremy Jackson, who argues that the synergistic effects of the 6th mass extinction have led to the flourishing of some species — such as jellyfish. Such thriving is almost certainly not what Joseph Beuys had in mind when he argued that we are creating the “total artwork of the future social order.” But what would happen if we held these provocations together: that human auto-destruction is a creation for other worlds, other species … other others? Artworks for Jellyfish collects writings from artists, theorists and scholars of science on the question of how art mediates and mitigates our imagination of the future in the wake of an extinction event — or, to put it a little bit differently, how to make artworks for jellyfish., https://www.librarystack.org/artworks-for-jellyfish-and-other-others/?ref=unknown
- Published
- 2022
14. A brain atlas of the camouflaging dwarf cuttlefish,Sepia bandensis
- Author
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Tessa G. Montague, Isabelle J. Rieth, Sabrina Gjerswold-Selleck, Daniella Garcia-Rosales, Sukanya Aneja, Dana Elkis, Nanyan Zhu, Sabrina Kentis, Frederick A. Rubino, Adriana Nemes, Katherine Wang, Luke A. Hammond, Roselis Emiliano, Rebecca A. Ober, Jia Guo, and Richard Axel
- Abstract
SummaryThe coleoid cephalopods (cuttlefish, octopus, and squid) are a group of soft-bodied marine mollusks that exhibit an array of interesting biological phenomena, including dynamic camouflage, complex social behaviors, prehensile regenerating arms, and large brains capable of learning, memory, and problem-solving [1–10]. The dwarf cuttlefish,Sepia bandensis, is a promising model cephalopod species due to its small size, substantial egg production, short generation time, and dynamic social and camouflage behaviors [11]. Cuttlefish dynamically camouflage to their surroundings by changing the color, pattern and texture of their skin. Camouflage is optically-driven, and is achieved by expanding and contracting hundreds of thousands of pigment-filled saccules (chromatophores) in the skin, which are controlled by motor neurons emanating from the brain. We generated a dwarf cuttlefish brain atlas using magnetic resonance imaging (MRI), deep learning, and histology, and we built an interactive web tool (cuttlebase.org) to host the data. Guided by observations in other cephalopods [12–20], we identified 32 brain lobes, including two large optic lobes (75% the total volume of the brain), chromatophore lobes whose motor neurons directly innervate the chromatophores of the color-changing skin, and a vertical lobe that has been implicated in learning and memory. This brain atlas provides a valuable tool for exploring the neural basis of cuttlefish behavior.
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- 2022
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15. A brain atlas of the camouflaging dwarf cuttlefish,Sepia bandensis
- Author
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Montague, Tessa G., primary, Rieth, Isabelle J., additional, Gjerswold-Selleck, Sabrina, additional, Garcia-Rosales, Daniella, additional, Aneja, Sukanya, additional, Elkis, Dana, additional, Zhu, Nanyan, additional, Kentis, Sabrina, additional, Rubino, Frederick A., additional, Nemes, Adriana, additional, Wang, Katherine, additional, Hammond, Luke A., additional, Emiliano, Roselis, additional, Ober, Rebecca A., additional, Guo, Jia, additional, and Axel, Richard, additional
- Published
- 2022
- Full Text
- View/download PDF
16. Accelerating Platform Deployments in the Cloud: A qualitative assessment based on CORD
- Author
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Adam Broadbent, José Soler, Paul Veitch, and Angelos Mimidis Kentis
- Subjects
Deployment time ,Cord ,Network Functions Virtualization ,Computer science ,business.industry ,Cloud computing ,KPIs ,Cloudnative ,NFV ,Platform ,Systems engineering ,Performance indicator ,business ,5G - Abstract
Influenced by the success of cloudification of Information Technology (IT) services, 5th Generation (5G) networks are also expected to leverage the benefits of virtualization and network programmability. Doing so will provide the necessary level of automation and flexibility to meet the stringent requirements of 5G services. Multiple orchestration platforms, tailored towards Telco cloud-based deployments, have been released (e.g., CORD, OSM, OPFNV), which facilitate the integration of virtualization and network programmability. However, these platforms are complex software stacks, making their deployment a time-consuming and sometimes challenging task. This paper presents an investigation of possible deployment best practices using the CORD platform as a use-case. The results show a considerable reduction in deployment time (approximately 67%), without an increase in the complexity of the deployment process. Moreover, this paper includes a list of “lessons-learned” from using the CORD platform. These lessons will hopefully help improve future releases of CORD (and similar Telco cloud platforms).
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- 2020
- Full Text
- View/download PDF
17. SDN-Enabled Management of Access Infrastructures and Cloudbased Platforms
- Author
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Kentis, Angelos Mimidis
- Abstract
5th Generation (5G) networks aim to increase network convergence by allowing a single network architecture to serve any traffic type, while simultaneously, meeting their respective requirements. As a result, 5G networks must be characterized by flexibility, dynamicity, and determinism. Flexibility means that the network should scale its resources depending on the current load to ensure performance without resource overprovisioning. Dynamicity is the ability to modify the behavior of the network following a programmatic approach instead of relying on static (preconfigured) configurations. Finally, if 5G is to cater for mission-critical/time-sensitive applications such as industrial automation, it should provide deterministic and timely treatment for packets of these traffic types. The reason a new network architecture is required is that the current networking paradigm is based on static configurations and monolithic service deployments and thus lacks the characteristics mentioned above. Recent years have seen the emergence of three networking paradigms that, if used appropriately, can provide high degrees of flexibility, dynamicity, and determinism. Namely, these are the Software Defined Networking (SDN), the Network Function Virtualization (NFV), and the Time Sensitive Networking (TSN) paradigms. By separating the network control plane from the data plane and logically centralizing it into an SDN Controller (SDNC), SDN allows for the dynamic/programmatic control of the network infrastructure. NFV, on the other hand, provides flexibility and scalability concerning service placement through virtualization and orchestration mechanisms, as network services can be instantiated, configured, and scaled on-demand. Finally. TSN guarantees the deterministic and timely treatment of time-sensitive traffic, without the need for a separate network infrastructure. The contributions of this Ph.D. thesis are towards these three paradigms and specifically towards investigating their applicability in different scenarios and identifying and addressing some of their limitations. To provide deterministic treatment of time-sensitive traffic, TSN utilizes a scheduling-based approach in which a network-wide schedule controls the transmission capabilities of each egress port in the network. Chapter 3, of this thesis, provides two contributions to this scheduling problem; 1) It proposes a heuristic methodology for generating the network-wide schedules and 2) it investigates how the forwarding decisions for time-sensitive traffic can affect the quality of these schedules. As part of future work, this chapter also presents a network architecture which integrates TSN into an SDN/NFV framework. As the default location for placement of virtualized service components, Data Centers (DC) will be an integral part of any 5G deployment. Given the stringent characteristics of 5G services, it is vital to identify and address any limitations of the SDN paradigm concerning a DC environment. Chapter 4 of this thesis identifies three of these limitations and presents solutions that can mitigate them. Specifically, chapter 4 provides the following contributions; 1) it proposes and presents two SDN-based network policy framework solutions that facilitate management of heterogeneous network infrastructures, 2) it investigates the applicability of Traffic Engineering (TE) in the context of SDN, and 3) it identifies the issue of limited capacity in network devices concerning the storage of network flow rules and proposes two solutions. Finally, 5G deployments are expected to comprise a variety of Management and Operation (MANO) platforms as the different 5G services will require different support functions and guarantees. This multi-platform characteristic can increase the overall complexity of managing a 5G network, as each platform can bring its unique Application Programming Interfaces (API), protocols, and workflows. Chapter 5 of this thesis considers this issue and presents and validates a centralized and technology-agnostic framework for the deployment and management of 5G platforms and services. Moreover, chapter 5 investigates two additional research items. The first identifies and addresses limitations in the deployment process of a current state-of-the-art 5G platform solution, and the second identifies a set of requirements that SDNCs should meet to be considered as ready for the next-generation of 5G platforms.
- Published
- 2020
18. Accelerating Platform Deployments in the Cloud: A qualitative assessment based on CORD
- Author
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Kentis, Angelos Mimidis, Soler, José, Broadbent, Adam, Veitch, Paul, Kentis, Angelos Mimidis, Soler, José, Broadbent, Adam, and Veitch, Paul
- Abstract
Influenced by the success of cloudification of Information Technology (IT) services, 5th Generation (5G) networks are also expected to leverage the benefits of virtualization and network programmability. Doing so will provide the necessary level of automation and flexibility to meet the stringent requirements of 5G services. Multiple orchestration platforms, tailored towards Telco cloud-based deployments, have been released (e.g., CORD, OSM, OPFNV), which facilitate the integration of virtualization and network programmability. However, these platforms are complex software stacks, making their deployment a time-consuming and sometimes challenging task. This paper presents an investigation of possible deployment best practices using the CORD platform as a use-case. The results show a considerable reduction in deployment time (approximately 67%), without an increase in the complexity of the deployment process. Moreover, this paper includes a list of “lessons-learned” from using the CORD platform. These lessons will hopefully help improve future releases of CORD (and similar Telco cloud platforms).
- Published
- 2020
19. Accelerating Platform Deployments in the Cloud: A Qualitative Assessment Based on CORD
- Author
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Kentis, Angelos Mimidis, primary, Soler, Jose, additional, Broadbent, Adam, additional, and Veitch, Paul, additional
- Published
- 2020
- Full Text
- View/download PDF
20. Effects of Exchange Rate Determinants on Financial Performance of Multinational Companies
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Kentis Musimbi Mulinya and Tobias Olweny
- Subjects
Inflation ,Exchange rate ,Return on assets ,Balance of payments ,Return on equity ,media_common.quotation_subject ,Debt ,Government debt ,General Medicine ,Business ,Monetary economics ,Market value ,media_common - Abstract
Foreign exchange is one of the macroeconomic variables which affect the financial performance of firms. Fluctuations in the foreign exchange rate have an effect on the operating cashflows, investment decisions, profits, sales and a firm’s market value. Foreign exchange rate level is determined by various factors which include the balance of payment, terms of trade, inflation and government borrowing. Given the importance of multinational firms to the economy of Kenya, it is crucial to determine the effect of determinants of foreign exchange on their performance. The objective of the study was to determine the effect foreign exchange determinants on the financial performance of multinational companies in Kenya. The independent variables included balance of payment, government debt, terms of trade and inflation. Measurement of financial performance was done using return on equity and return on assets. The study was anchored by the balance of payments theory, Keynesian theory of public debt, theory of international trade and the quantity theory of money. The study sampled four multinational companies operating in the nation of Kenya. The period covered by the study was 2002-2017. Data collected for the study was from both the central bank publications and financial statements of multinational companies. Study data was evaluated using panel data. The fixed effects model was used for the study. The study established that the balance of payments had a negative as well as statistically significant impact on return on assets. The study also established that government debt had a positive and significant effect on return on assets. Terms of trade and inflation were found to have positive but statistically insignificant effects on return on assets. The balance of payment and inflation had a negative and statistically significant effect on the return on equity. The terms of trade was found to have a positive but statistically insignificant effect on the return on equity. Government debt had a positive and statistically significant effect on return on equity.
- Published
- 2019
- Full Text
- View/download PDF
21. The Next Generation Platform as A Service: Composition and Deployment of Platforms and Services
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Mimidis-Kentis, A, Soler, J, Veitch, P, Broadbent, A, Mobilio, M, Riganelli, O, Van Rossem, S, Tavernier, W, Sayadi, B, Mimidis-Kentis, A, Soler, J, Veitch, P, Broadbent, A, Mobilio, M, Riganelli, O, Van Rossem, S, Tavernier, W, and Sayadi, B
- Abstract
The emergence of widespread cloudification and virtualisation promises increased flexibility, scalability, and programmability for the deployment of services by Vertical Service Providers (VSPs). This cloudification also improves service and network management, reducing the Capital and Operational Expenses (CAPEX, OPEX). A truly cloud-native approach is essential, since 5G will provide a diverse range of services - many requiring stringent performance guarantees while maximising flexibility and agility despite the technological diversity. This paper proposes a workflow based on the principles of build-to-order, Build-Ship-Run, and automation; following the Next Generation Platform as a Service (NGPaaS) vision. Through the concept of Reusable Functional Blocks (RFBs), an enhancement to Virtual Network Functions, this methodology allows a VSP to deploy and manage platforms and services, agnostic to the underlying technologies, protocols, and APIs. To validate the proposed workflow, a use case is also presented herein, which illustrates both the deployment of the underlying platform by the Telco operator and of the services that run on top of it. In this use case, the NGPaaS operator facilitates a VSP to provide Virtual Network Function as a Service (VNFaaS) capabilities for its end customers.
- Published
- 2019
22. NGPaaS Framework for Enriched and Customized Virtual Network Functions-as-a-Service
- Author
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Veitch, Paul, Broadbent, Adam, Kentis, Angelos Mimidis, Soler, José, Mobilio, Marco, Tundo, Alessandro, Guzmán, Michell, Van Rossem, Steven, Veitch, Paul, Broadbent, Adam, Kentis, Angelos Mimidis, Soler, José, Mobilio, Marco, Tundo, Alessandro, Guzmán, Michell, and Van Rossem, Steven
- Abstract
This paper describes how the novel Next Generation Platform-as-a-Service (NGPaaS) framework can facilitate major benefits for Network Operators and Vertical Service Providers (VSPs) who wish to leverage Virtual Network Functions-as-a-Service (VNFaaS) capabilities. Network Operators can benefit by providing an on-demand PaaS with required features for the VSPs, thus generating new revenue streams but with low operational overhead due to the high degree of automation. VSPs can benefit from the PaaS-oriented approach, by being able to flexibly on-board new VNF types and “value-added” service capabilities like monitoring, healing and profiling, to deliver customized service blueprints to meet the needs of their end customers. The paper outlines the design of an early prototype, built on the Open-CORD platform and using industry-standard Virtualised Network Functions (VNFs).
- Published
- 2019
23. Build-Ship-Run approach for a CORD-in-a-Box deployment
- Author
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Canellas, Ferran, Bonjorn, Nestor, Kentis, Angelos Mimidis, Soler, José, Canellas, Ferran, Bonjorn, Nestor, Kentis, Angelos Mimidis, and Soler, José
- Abstract
5G is expected to provide high bandwidth and low latency communications, thus allowing Telco operators to provide new services to their end customers. This increase in performance is achieved through the migration of network functions from the core to the edge of the network and facilitated by the flexibility and automation provided by Software Defined Networking (SDN) and Network Function Virtualization (NFV). To pave the way to 5G, and simplify the management of 5G deployments a number of SDN/VNF platforms has been developed in the recent years. However deploying and configuring the platforms themselves, is a complex and time consuming task which can act as a barrier to their adoption by Telco operators. This is because Telco Operators strife for fast provisioning times and zero-touch provisioning. Based on this observation, this paper proposes a Build-Ship-Run platform deployment using Central Office Rearchitected as a Datacenter (CORD) as an exemplar platform. The proposed approach is based on the use of compressed Virtual Machine snapshots, which allow preconfigured CORDflavors to be fetched, uncompressed and deployed on demand. Using the proposed workflow, a deployment time seven times better than the raw installation is demonstrated.
- Published
- 2019
24. Policy Framework Prototype for ONOS
- Author
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Canellas Cruz, Ferran, Kentis, Angelos Mimidis, Bonjorn, Nestor, Soler, José, Canellas Cruz, Ferran, Kentis, Angelos Mimidis, Bonjorn, Nestor, and Soler, José
- Abstract
The Software Defined Networking (SDN) and Network Function Virtualization (NFV) paradigms can provide increased levels of flexibility, automation and programmability to fields related to Cloud and 5G technologies. One field that can benefit greatly from SDN/NFV is that of policy-based network management. Building upon previous work, this paper presents a network policy framework prototype for the ONOS SDN controller. This paper presents an architecture, where the policy manager and the different policy types are disaggregated as different applications (communicating through dedicated REST APIs). This allows for the ad-hoc installation and removal of new policy types to the policy framework, without causing systemwide disruptions. Details of the underlying framework design are provided, together with concrete insight on the network policy prototype implementation. The prototype is then validated through three Proof of Concept (PoC) policy types, a firewall, a NAT and a connectivity policy.
- Published
- 2019
25. The Next Generation Platform as A Service: Composition and Deployment of Platforms and Services
- Author
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Kentis, Angelos Mimidis, Soler, José, Veitch, Paul, Broadbent, Adam, Mobilio, Marco, Riganelli, Oliviero, Van Rossem, Steven, Tavernier, Wouter, Sayadi, Bessem, Kentis, Angelos Mimidis, Soler, José, Veitch, Paul, Broadbent, Adam, Mobilio, Marco, Riganelli, Oliviero, Van Rossem, Steven, Tavernier, Wouter, and Sayadi, Bessem
- Abstract
The emergence of widespread cloudification and virtualisation promises increased flexibility, scalability, and programmability for the deployment of services by Vertical Service Providers (VSPs). This cloudification also improves service and network management, reducing the Capital and Operational Expenses (CAPEX, OPEX). A truly cloud-native approach is essential, since 5G will provide a diverse range of services - many requiring stringent performance guarantees while maximising flexibility and agility despite the technological diversity. This paper proposes a workflow based on the principles of build-to-order, Build-Ship-Run, and automation; following the Next Generation Platform as a Service (NGPaaS) vision. Through the concept of Reusable Functional Blocks (RFBs), an enhancement to Virtual Network Functions, this methodology allows a VSP to deploy and manage platforms and services, agnostic to the underlying technologies, protocols, and APIs. To validate the proposed workflow, a use case is also presented herein, which illustrates both the deployment of the underlying platform by the Telco operator and of the services that run on top of it. In this use case, the NGPaaS operator facilitates a VSP to provide Virtual Network Function as a Service (VNFaaS) capabilities for its end customers.
- Published
- 2019
26. SDN Controller Requirements for Next Generation Telco PaaS
- Author
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Kentis, Angelos Mimidis, Soler, José, Fernando, Díaz, Aurora, Ramos, Olivier, Choisy, Aravinthan, Gopalasingham, Kentis, Angelos Mimidis, Soler, José, Fernando, Díaz, Aurora, Ramos, Olivier, Choisy, and Aravinthan, Gopalasingham
- Abstract
This paper presents an analysis of requirements to Software Defined Network (SDN) Controllers (SDNC), from the point of view of the Telco’s Next Generation Platform as a Service (NGPaaS) functional and architectural needs. Numerous requirements have been identified, which can be grouped in 4 categories: domain-based, modularity-based, related to the SDN and Network Function Virtualization (NFV) integration and finally policy-based. These requirements are later mapped into the ONOS SDN controller, with the scope of identifying possible gaps and points of improvement.
- Published
- 2019
27. Analysis of Traffic Engineering capabilities for SDN-based Data Center Networks
- Author
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Lars Dittmann, Artur Pilimon, Angelos Mimidis Kentis, and Sarah Ruepp
- Subjects
Service (systems architecture) ,business.industry ,Emerging technologies ,Computer science ,Distributed computing ,Testbed ,Traffic Engineering ,Cloud computing ,SDN ,Traffic engineering ,Scalability ,Data center ,Software-defined networking ,business ,Data Center - Abstract
In the recent years more and more existing services have moved from local execution environments into the cloud. In addition, new cloud-based services are emerging, which are characterized by very stringent delay requirements. This trend puts a stress in the existing monolithic architecture of Data Center Networks (DCN), thus creating the need to evolve them. Traffic Engineering (TE) has long been the way of attacking this problem, but as with DCN, needs to evolve by encompassing new technologies and paradigms. This paper provides a comprehensive analysis of current DCN operational and TE techniques focusing on their limitations. Then, it highlights the benefits of incorporating the Software Defined Networking (SDN) paradigm to address these limitations. Furthermore, it illustrates two methodologies and addresses the scalability aspect of DCN-oriented TE, network and service testing, by presenting a hybrid physical-simulated SDN enabled testbed for TE studies.
- Published
- 2018
- Full Text
- View/download PDF
28. A Novel Algorithm for Flow-Rule Placement in SDN Switches
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Michael Stübert Berger, Artur Pilimon, José Soler, Angelos Mimidis-Kentis, and Sarah Ruepp
- Subjects
business.industry ,Computer science ,Testbed ,020206 networking & telecommunications ,020302 automobile design & engineering ,02 engineering and technology ,Content-addressable memory ,Networking hardware ,SDN ,Software ,0203 mechanical engineering ,Packet loss ,0202 electrical engineering, electronic engineering, information engineering ,Table (database) ,OpenFlow Pipelines ,Routing (electronic design automation) ,business ,TCAM ,Traffic generation model ,Algorithm ,Flow tables - Abstract
The forwarding rules, used by the legacy and SDN network devices to perform routing/forwarding decisions, are generally stored in Ternary Content Addressable Memory (TCAM) modules, which offer constant look-up times, but have limited capacity, due to their high capital and operational costs, high power consumption and high silicon footprint. To counter this limitation, some commercial switches offer both, hardware and software flow table implementations, termed hybrid flow table architecture in this paper. The software-based tables are stored in non-TCAM memory modules, which offer higher capacity, but with slower lookup times. In addition, these memory modules are limited in terms of how many requests they can serve per time unit. Thus, exceeding this threshold will lead to packet loss in the network. This paper proposes a novel placement algorithm, which dynamically decides whether a new flow rule should be placed in a hardware (expensive) or a software (cheap) table. The placement decisions are based on a number of criteria with the goal to increase the utilization of the software-based table, without introducing performance degradation in the network in terms of significant delay and packet loss. The performance of the placement algorithm was evaluated through experimental measurements in a testbed, which comprises a hybrid SDN switch, a server performing traffic generation and a server hosting the SDN controller. The results indicate that, by limiting the maximum allowed processing capacity of the software table, the number of accommodated flows is significantly increased, while bounding any excessive delays and avoiding packet loss.
- Published
- 2018
- Full Text
- View/download PDF
29. Policy Framework Prototype for ONOS
- Author
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Ferran Canellas Cruz, Angelos Mimidis-Kentis, and José Soler
- Abstract
This prototype allows Service Providers to define topology-wide and SDN-based (ONOS) network policies, by means of abstracting the underlying ONOS implementation and the use of generic interfaces. This prototype disaggregates the policy manager and the policies as different ONOS apps that communicate through REST, allowing the addition of new policy types without affecting the policy manager. Currently, 3 policy types are supported: Firewall, NAT and Connectivity.
- Published
- 2018
30. Next Generation PaaS and CORD Cloud-Native Telco services
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Ferran Canellas Cruz, Angelos Mimidis-Kentis, and José Soler
- Published
- 2018
31. The Next Generation Platform as A Service: Composition and Deployment of Platforms and Services
- Author
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Mimidis-Kentis, Angelos, primary, Soler, Jose, additional, Veitch, Paul, additional, Broadbent, Adam, additional, Mobilio, Marco, additional, Riganelli, Oliviero, additional, Van Rossem, Steven, additional, Tavernier, Wouter, additional, and Sayadi, Bessem, additional
- Published
- 2019
- Full Text
- View/download PDF
32. The Next Generation Platform as a Service Cloudifying Service Deployments in Telco-Operators Infrastructure
- Author
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Kentis, A, Zaballa, E, Soler, J, Bessem, S, Roullet, L, Rossem, S, Pinneterre, S, Paolino, M, Raho, D, Du, X, Chesterfield, J, Flouris, M, Mariani, L, Riganelli, O, Mobilio, M, Ramos, A, Pavon, I, Broadbent, A, Veitch, P, Zembra, M, Kentis, A, Zaballa, E, Soler, J, Bessem, S, Roullet, L, Rossem, S, Pinneterre, S, Paolino, M, Raho, D, Du, X, Chesterfield, J, Flouris, M, Mariani, L, Riganelli, O, Mobilio, M, Ramos, A, Pavon, I, Broadbent, A, Veitch, P, and Zembra, M
- Abstract
5G standard emerges at a particular time in technology history when cloud transforms deeply almost all industries and services: it becomes obvious that innovations have to be made cloud-native for being successful. 5G must become the ubiquitous fabric blending universal connectivity (to humans, robots, sensors...) with cloud versatility and scalability. For realizing this vision, another model than laaS must be adopted, the Platform as a Service (PaaS), which should be built to support telco-grade requirements and combine all sort of third-party applications. These are the core objectives of the Next Generation Platform as a Service (NGPaaS) project, a H2020 5G PPP Phase 2 project. The paper presents the project fundamentals, its architectural proposal and most relevant features
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- 2018
33. Re-Factored Operational Support Systems for the Next Generation Platform-as-a-Service (NGPaaS)
- Author
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Veitch, P, Broadbent, A, Van Rossem, S, Sayadi, B, Natarianni, L, Al Jammal, B, Roullet, L, Kentis, A, Ollora Zaballa, E, Soler, J, Pinniterre, S, Paolino, M, Ramos, A, Du, X, Flouris, M, Mariani, L, Riganelli, O, Mobilio, M, Shatnawi, A, Orru', M, Zembra, M, ORRU', MATTEO, Veitch, P, Broadbent, A, Van Rossem, S, Sayadi, B, Natarianni, L, Al Jammal, B, Roullet, L, Kentis, A, Ollora Zaballa, E, Soler, J, Pinniterre, S, Paolino, M, Ramos, A, Du, X, Flouris, M, Mariani, L, Riganelli, O, Mobilio, M, Shatnawi, A, Orru', M, Zembra, M, and ORRU', MATTEO
- Abstract
Platform-As-A-Service (PaaS) systems offer customers a rich environment in which to build, deploy, and run applications. Today's PaaS offerings are tailored mainly to the needs of web and mobile applications developers, and involve a fairly rigid stack of components and features. The vision of the H2020 5GPPP Phase 2 Next Generation Platform-as-a-Service (NGPaaS) project is to enable "build-to-order" customized PaaSes, tailored to the needs of a wide range of use cases with telco-grade 5G characteristics. This paper sets out the salient and innovative features of NGPaaS and explores the impacts on Operational Support Systems and Business Support Systems (OSS/BSS), moving from fixed centralized stacks to a much more flexible and modular distributed architecture.
- Published
- 2018
34. VIM Adaptation Layer for CORD
- Author
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Canellas Cruz, Ferran, Kentis, Angelos Mimidis, Soler, José, Canellas Cruz, Ferran, Kentis, Angelos Mimidis, and Soler, José
- Published
- 2018
35. Analysis of Traffic Engineering capabilities for SDN-based Data Center Networks
- Author
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Pilimon, Artur, Kentis, Angelos Mimidis, Ruepp, Sarah Renée, Dittmann, Lars, Pilimon, Artur, Kentis, Angelos Mimidis, Ruepp, Sarah Renée, and Dittmann, Lars
- Abstract
In the recent years more and more existing services have moved from local execution environments into the cloud. In addition, new cloud-based services are emerging, which are characterized by very stringent delay requirements. This trend puts a stress in the existing monolithic architecture of Data Center Networks (DCN), thus creating the need to evolve them. Traffic Engineering (TE) has long been the way of attacking this problem, but as with DCN, needs to evolve by encompassing new technologies and paradigms. This paper provides a comprehensive analysis of current DCN operational and TE techniques focusing on their limitations. Then, it highlights the benefits of incorporating the Software Defined Networking (SDN) paradigm to address these limitations. Furthermore, it illustrates two methodologies and addresses the scalability aspect of DCN-oriented TE, network and service testing, by presenting a hybrid physical-simulated SDN enabled testbed for TE studies.
- Published
- 2018
36. Policy Framework Prototype for ONOS
- Author
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Canellas Cruz, Ferran, Kentis, Angelos Mimidis, Soler, José, Canellas Cruz, Ferran, Kentis, Angelos Mimidis, and Soler, José
- Abstract
This prototype allows Service Providers to define topology-wide and SDN-based (ONOS) network policies, by means of abstracting the underlying ONOS implementation and the use of generic interfaces. This prototype disaggregates the policy manager and the policies as different ONOS apps that communicate through REST, allowing the addition of new policy types without affecting the policy manager. Currently, 3 policy types are supported: Firewall, NAT and Connectivity.
- Published
- 2018
37. Next Generation PaaS and CORD Cloud-Native Telco services
- Author
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Canellas Cruz, Ferran, Kentis, Angelos Mimidis, Soler, José, Canellas Cruz, Ferran, Kentis, Angelos Mimidis, and Soler, José
- Published
- 2018
38. A Vision for the Next Generation Platform-as-a-Service
- Author
-
Van Rossem, Steven, Sayadi, Bessem, Roullet, Laurent, Kentis, Angelos Mimidis, Paolino, Michele, Veitch, Paul, Berde, Bela, Labrador, Ignacio, Ramos, Aurora, Tavernier, Wouter, Ollora Zaballa, Eder, Soler, José, Van Rossem, Steven, Sayadi, Bessem, Roullet, Laurent, Kentis, Angelos Mimidis, Paolino, Michele, Veitch, Paul, Berde, Bela, Labrador, Ignacio, Ramos, Aurora, Tavernier, Wouter, Ollora Zaballa, Eder, and Soler, José
- Abstract
In an increasingly interconnected world, new opportunities for telecom-based services are emerging. Innovative applications profit from cloud versatility and scalability, but require a platform to combine the optimized 5G network fabric with the advancements in the domain of cloud computing, Software Defined Networking (SDN) and Network Function Virtualization (NFV). In this multi-domain context, we find that available service platforms are lagging, because they tend to be tightly coupled to a constrained set of technologies. In practice, we need the flexibility to deploy different microservices over a heterogeneous range of infrastructure types, aggregating various virtualization, orchestration and control mechanisms. Moreover, the integration of the service requires collaboration among a wide mix of actors (e.g. developers, operators, hardware/software vendors, infrastructure/service providers or vertical integrators). We propose a next-generation Platform-asa-Service (NGPaaS), devised as a modular framework for the development and operation of network services, while targeting a high degree of both customization and automation. The presented architecture is built around a workflow-based orchestrator which coordinates custom-built tasks across a tailored group of specialized infrastructure or platforms. We also explain how NGPaaS enhances DevOps-principles, to achieve a more efficient integration process across the many isolated administrative domains in the modern telco landscape.
- Published
- 2018
39. Re-Factored Operational Support Systems for the Next Generation Platform-as-a-Service (NGPaaS)
- Author
-
Veitch, Paul, Broadbent, Adam, Van Rossem, Steven, Sayadi, Bessem, Natarianni, Lionel, Al Jammal, Bilal, Roullet, Laurent, Kentis, Angelos Mimidis, Ollora Zaballa, Eder, Soler, José, Pinniterre, Sebastien, Paolino, Michele, Ramos, Aurora, Du, X., Flouris, M., Mariani, L., Riganelli, O., Mobilio, M., Shatnawi, A., Orru, M., Zembra, M., Veitch, Paul, Broadbent, Adam, Van Rossem, Steven, Sayadi, Bessem, Natarianni, Lionel, Al Jammal, Bilal, Roullet, Laurent, Kentis, Angelos Mimidis, Ollora Zaballa, Eder, Soler, José, Pinniterre, Sebastien, Paolino, Michele, Ramos, Aurora, Du, X., Flouris, M., Mariani, L., Riganelli, O., Mobilio, M., Shatnawi, A., Orru, M., and Zembra, M.
- Abstract
Platform-As-A-Service (PaaS) systems offer customers a rich environment in which to build, deploy, and run applications. Today’s PaaS offerings are tailored mainly to the needs of web and mobile applications developers, and involve a fairly rigid stack of components and features. The vision of the H2020 5GPPP Phase 2 Next Generation Platform-as-a-Service (NGPaaS) project is to enable “build-to-order” customized PaaSes, tailored to the needs of a wide range of use cases with telcograde 5G characteristics. This paper sets out the salient and innovative features of NGPaaS and explores the impacts on Operational Support Systems and Business Support Systems (OSS/BSS), moving from fixed centralized stacks to a much more flexible and modular distributed architecture.
- Published
- 2018
40. Policy Framework for the Next Generation Platform as a Service
- Author
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Kentis, Angelos Mimidis, Ollora Zaballa, Eder, Soler, José, Kentis, Angelos Mimidis, Ollora Zaballa, Eder, and Soler, José
- Abstract
The Platform-as-a-Service (PaaS) model, allows service providers to build and deploy their services following streamlined work-flows. However, platforms deployed through the PaaS model can be very diverse in terms of technologies and involved subsystems (e.g. infrastructure, orchestration). Thus, the means for deploying and managing a service can significantly vary depending on the deployed platform. To address this issue, this paper proposes a policy-based framework designed for the Next Generation Platform-as-a-Service (NGPaaS). This framework allows service providers to define platform-wide and technology-agnostic policies to NGPaaS, by means of abstraction of the underlying platforms and the use of generic interfaces. The paper also presents a specific use case for the proposed framework, which targets network-oriented policies.
- Published
- 2018
41. A Novel Algorithm for Flow-Rule Placement in SDN Switches
- Author
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Kentis, Angelos Mimidis, Pilimon, Artur, Soler, José, Berger, Michael Stübert, Ruepp, Sarah Renée, Kentis, Angelos Mimidis, Pilimon, Artur, Soler, José, Berger, Michael Stübert, and Ruepp, Sarah Renée
- Abstract
The forwarding rules, used by the legacy and SDN network devices to perform routing/forwarding decisions, are generally stored in Ternary Content Addressable Memory (TCAM) modules, which offer constant look-up times, but have limited capacity, due to their high capital and operational costs, high power consumption and high silicon footprint. To counter this limitation, some commercial switches offer both, hardware and software flow table implementations, termed hybrid flow table architecture in this paper. The software-based tables are stored in non-TCAM memory modules, which offer higher capacity, but with slower lookup times. In addition, these memory modules are limited in terms of how many requests they can serve per time unit. Thus, exceeding this threshold will lead to packet loss in the network. This paper proposes a novel placement algorithm, which dynamically decides whether a new flow rule should be placed in a hardware (expensive) or a software (cheap) table. The placement decisions are based on a number of criteria with the goal to increase the utilization of the software-based table, without introducing performance degradation in the network in terms of significant delay and packet loss. The performance of the placement algorithm was evaluated through experimental measurements in a testbed, which comprises a hybrid SDN switch, a server performing traffic generation and a server hosting the SDN controller. The results indicate that, by limiting the maximum allowed processing capacity of the software table, the number of accommodated flows is significantly increased, while bounding any excessive delays and avoiding packet loss.
- Published
- 2018
42. The Next Generation Platform as a Service Cloudifying Service Deployments in Telco-Operators Infrastructure
- Author
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Kentis, Angelos Mimidis, Ollora Zaballa, Eder, Soler, José, Bessem, S., Roullet, Laurent, Van Rossem, S., Pinneterre, S., Paolino, M., Raho, D., Du, X., Mariani, L., Ramos, A., Labrador, I., Broadbent, A., Zembra, M., Kentis, Angelos Mimidis, Ollora Zaballa, Eder, Soler, José, Bessem, S., Roullet, Laurent, Van Rossem, S., Pinneterre, S., Paolino, M., Raho, D., Du, X., Mariani, L., Ramos, A., Labrador, I., Broadbent, A., and Zembra, M.
- Abstract
5G standard emerges at a particular time in technology history when cloud transforms deeply almost all industries and services: it becomes obvious that innovations have to be made cloud-native for being successful. 5G must become the ubiquitous fabric blending universal connectivity (to humans, robots, sensors…) with cloud versatility and scalability. For realizing this vision, another model than IaaS must be adopted, the Platform as a Service (PaaS), which should be built to support telco-grade requirements and combine all sort of third-party applications. These are the core objectives of the Next Generation Platform as a Service (NGPaaS) project, a H2020 5G PPP Phase 2 project. The paper presents the project fundamentals, its architectural proposal and most relevant features.
- Published
- 2018
43. Effects of Port Congestion in the Gate Control List Scheduling of Time Sensitive Networks
- Author
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José Soler, Angelos Mimidis Kentis, and Michael Stübert Berger
- Subjects
Ethernet ,Schedule ,TSN ,Computer science ,business.industry ,020206 networking & telecommunications ,02 engineering and technology ,Network topology ,020202 computer hardware & architecture ,Scheduling (computing) ,Traffic Scheduling ,Shifting bottleneck heuristic ,Logic gate ,0202 electrical engineering, electronic engineering, information engineering ,business ,Multipath propagation ,Computer network ,Jitter - Abstract
Time Sensitive Networking (TSN) can provide deterministic traffic behavior over Ethernet networks, for time sensitive traffic, whilst also bound the delay/jitter. To do so, the IEEE TSN working group introduced a network-wide transmission port scheduling mechanism. The duration of this schedule is directly related with the delay; hence reducing it can be beneficial within the TSN paradigm. This paper investigates the effects of port congestion, in the duration of the network wide schedule. A congested port can make scheduling more complex, leading to longer network-wide schedules. To verify this, the same set of experiments was repeated, with and without considering port congestion during path allocation. The computed paths were given as input to an implementation of the shifting bottleneck heuristic algorithm. The shifting bottleneck heuristic, computed the network-wide gating schedule. The results show that with port congestion as a metric during path allocation the duration of the gating schedule in multipath networks can be reduced up to 26%.
- Published
- 2017
- Full Text
- View/download PDF
44. A Novel Algorithm for Flow-Rule Placement in SDN Switches
- Author
-
Mimidis-Kentis, Angelos, primary, Pilimon, Artur, additional, Soler, Jose, additional, Berger, Michael, additional, and Ruepp, Sarah, additional
- Published
- 2018
- Full Text
- View/download PDF
45. Analysis of traffic engineering capabilities for SDN-based data center networks
- Author
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Pilimon, Artur, primary, Kentis, Angelos Mimidis, additional, Ruepp, Sarah, additional, and Dittmann, Lars, additional
- Published
- 2018
- Full Text
- View/download PDF
46. Effects of Port Congestion in the Gate Control List Scheduling of Time Sensitive Networks
- Author
-
Kentis, Angelos Mimidis, Berger, Michael Stübert, Soler, José, Kentis, Angelos Mimidis, Berger, Michael Stübert, and Soler, José
- Abstract
Time Sensitive Networking (TSN) can provide deterministic traffic behavior over Ethernet networks, for time sensitive traffic, whilst also bound the delay/jitter. To do so, the IEEE TSN working group introduced a network-wide transmission port scheduling mechanism. The duration of this schedule is directly related with the delay; hence reducing it can be beneficial within the TSN paradigm. This paper investigates the effects of port congestion, in the duration of the network wide schedule. A congested port can make scheduling more complex, leading to longer network-wide schedules. To verify this, the same set of experiments was repeated, with and without considering port congestion during path allocation. The computed paths were given as input to an implementation of the shifting bottleneck heuristic algorithm. The shifting bottleneck heuristic, computed the network-wide gating schedule. The results show that with port congestion as a metric during path allocation the duration of the gating schedule in multipath networks can be reduced up to 26%.
- Published
- 2017
47. Effects of port congestion in the gate control list scheduling of time sensitive networks
- Author
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Kentis, Angelos Mimidis, primary, Berger, Michael Stubert, additional, and Soler, Jose, additional
- Published
- 2017
- Full Text
- View/download PDF
48. Kentis, Angelos Mimidis
- Author
-
Kentis, Angelos Mimidis and Kentis, Angelos Mimidis
- Published
- 2016
49. Dynamic aggregation of traffic flows in SDN Applied to backhaul networks
- Author
-
Kentis, Angelos Mimidis, Caba, Cosmin Marius, Soler, José, Kentis, Angelos Mimidis, Caba, Cosmin Marius, and Soler, José
- Abstract
A challenge in the adoption of the OpenFlow (OF)-based SDN paradigm is related to the limited number of OF rules supported by the network devices. The technology used to implement the OF rules is TCAM, which is expensive and power demanding. Due to this, the network devices are either very costly or they can support a very limited number of OF rules. One way to cope with this limitation, is to perform the same logic but with fewer OF rules in the devices. As a demonstration of this operational strategy, the current paper proposes a service for traffic flow aggregation which reduces the number of OF rules needed in the network devices, without impacting the control plane logic. The proposed traffic flow aggregation service is tested on a set of topologies specific to the backhaul network, since they aggregate a large amount of traffic flows. The results illustrate significant reductions in the number of OF rules in network devices, thus a lower demand on TCAM capacity.
- Published
- 2016
50. National Nuclear Forensics Expertise Development Program
- Author
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Samantha E. Kentis, William D. Ulicny, Kenan Ünlü, Susan Heller-Zeisler, and Rolf Zeisler
- Subjects
Engineering ,ComputingMilieux_THECOMPUTINGPROFESSION ,business.industry ,Nuclear forensics ,University faculty ,Homeland security ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,ComputingMilieux_LEGALASPECTSOFCOMPUTING ,Expertise development ,Fiscal year ,General partnership ,Workforce ,Engineering ethics ,business ,Arms control - Abstract
Over the course of the 2009 Federal Fiscal Year the United States (U.S.) Department of Homeland Security (DHS), in partnership with the Departments of Defense (DoD) and Energy (DOE), is continuing existing programs and introducing new programs designed to maintain a highly qualified, enduring workforce capable of performing the technical nuclear forensics mission. These student and university programs are designed to recruit the best and brightest students, develop university faculty and research capabilities, and engage the national laboratories in fields of study with application in nuclear forensics. This comprehensive effort constitutes the National Nuclear Forensics Expertise Development Program.
- Published
- 2009
- Full Text
- View/download PDF
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