@inproceedings{2481, abstract = {{Network function virtualization requires scaling and placement, deciding the number and the location of function instances. Current approaches are limited in flexibility and practical applicability. Specifically, we study dynamic, single-step, joint scaling and placement of network services with bidirectional flows traversing Physical or Virtual Network Functions (VNFs) and returning to their sources. We develop models to support stateful components and legacy network functions with fixed locations in these network services as well as the possibility of reusing VNFs across network services. We formalize the problem of jointly scaling and placing such network services as a mixed- integer linear program (MILP). We show that this problem is NP-complete and also present a heuristic algorithm to find good solutions in short time. In an extensive evaluation with realistic scenarios, we investigate the capabilities of the two approaches.}}, author = {{Dräxler, Sevil and Schneider, Stefan Balthasar and Karl, Holger}}, booktitle = {{4th IEEE International Conference on Network Softwarization (NetSoft 2018)}}, location = {{Montreal}}, pages = {{123----131}}, publisher = {{IEEE}}, title = {{{ Scaling and Placing Bidirectional Services with Stateful Virtual and Physical Network Functions}}}, year = {{2018}}, } @inproceedings{2482, author = {{Dräxler, Sevil and Karl, Holger and Razzaghi Kouchaksaraei, Hadi and Machwe, Azahar and Dent-Young, Crispin and Katsalis, Kostas and Samdanis, Konstantinos}}, booktitle = {{27th European Conference on Networks and Communications (EUCNC 2018)}}, location = {{Ljubljana}}, title = {{{5G OS: Control and Orchestration of Services on Multi-Domain Heterogeneous 5G Infrastructures}}}, year = {{2018}}, } @techreport{2483, abstract = {{Understanding the behavior of distributed cloud service components in different load situations is important for efficient and automatic management and orchestration of these services. For this purpose and for practical research in distributed cloud computing in general, there is need for benchmarks and experimental data. In this paper, we describe our experiments for characterizing the relationship between resource demands of application components and the expected performance of applica- tions. We present initial results for predicting the interdependence between resource demands and performance characteristics using support vector regression and polynomial regression models. The data gathered from our experiments is publicly available.}}, author = {{Dräxler, Sevil and Peuster, Manuel and Illian, Marvin and Karl, Holger}}, title = {{{Towards Predicting Resource Demands and Performance of Distributed Cloud Services}}}, year = {{2018}}, } @article{24953, author = {{Bauer, Anna and Sacher, Marc}}, journal = {{Phydid B, Didaktik der Physik, Beiträge zur DPG-Frühjahrstagung}}, title = {{{Kompetenzorientierte, universitäre Laborpraktika - Das Paderborner Physik Praktikum (3P)}}}, year = {{2018}}, } @inbook{24960, author = {{Bauer, Anna and Reinhold, Peter and Sacher, Marc}}, booktitle = {{Qualitätsvoller Chemie- und Physikunterricht – normative und empirische Dimensionen}}, editor = {{Maurer, Christian}}, pages = {{919--922}}, publisher = {{Gesellschaft für Didaktik der Chemie und Physik}}, title = {{{Operationalisierung der experimentellen Kompetenz (Physik)Studierender}}}, year = {{2018}}, } @inproceedings{2857, author = {{Mohr, Felix and Lettmann, Theodor and Hüllermeier, Eyke and Wever, Marcel Dominik}}, booktitle = {{Proceedings of the 1st ICAPS Workshop on Hierarchical Planning}}, location = {{Delft, Netherlands}}, pages = {{31--39}}, publisher = {{AAAI}}, title = {{{Programmatic Task Network Planning}}}, year = {{2018}}, } @inproceedings{2862, author = {{Blömer, Johannes and Eidens, Fabian and Juhnke, Jakob}}, booktitle = {{Topics in Cryptology - {CT-RSA} 2018 - The Cryptographers' Track at the {RSA} Conference 2018, Proceedings}}, isbn = {{9783319769523}}, issn = {{0302-9743}}, location = {{San Francisco, CA, USA}}, pages = {{470--490}}, publisher = {{Springer International Publishing}}, title = {{{Practical, Anonymous, and Publicly Linkable Universally-Composable Reputation Systems}}}, doi = {{10.1007/978-3-319-76953-0_25}}, year = {{2018}}, } @inproceedings{2471, author = {{Mohr, Felix and Wever, Marcel Dominik and Hüllermeier, Eyke}}, booktitle = {{SCC}}, location = {{San Francisco, CA, USA}}, publisher = {{IEEE Computer Society}}, title = {{{On-The-Fly Service Construction with Prototypes}}}, doi = {{10.1109/SCC.2018.00036}}, year = {{2018}}, } @inproceedings{2666, abstract = {{Supporting the vast variety of network services’ management and orchestration requirements is one of the main challenges that Network Function Virtualization (NFV) is dealing with. While general management requirements such as Virtual Network Function (VNF) resource requirements can be specified by the service developers using service descriptors, specific management operations like VNF-specific configuration cannot be performed by these descriptors. On the other hand, it is inefficient and also very challenging for Management and Orchestration (MANO) frameworks to provide all specific-management operations for every individual network service and their constituent VNFs. To mitigate this issue, we propose the use of service-specific programs called Specific Managers (SMs) that can customize management and orchestration of network services and also extend the capability of MANO frameworks to support per-service management and orchestration. The results of our evaluation show that the higher flexibility and programmability enabled by SMs improve the performance of the service performance and also utilises the service provider resources more efficiently.}}, author = {{Razzaghi Kouchaksaraei, Hadi and Dräxler, Sevil and Peuster, Manuel and Karl, Holger}}, booktitle = {{2018 European Conference on Networks and Communications (EuCNC)}}, location = {{Ljubljana, Slovenia}}, publisher = {{IEEE}}, title = {{{Programmable and Flexible Management and Orchestration of Virtualized Network Functions}}}, year = {{2018}}, } @inproceedings{2667, abstract = {{Developing cloud applications using a microservice architecture allows their functional blocks to be distributed and deployed on multiple Cloud infrastructures. This enables service providers to mix and match Cloud-based microservices and Virtual Network Functions (VNFs) that are provided by Network Function Virtualization (NFV). Provisioning complex services containing VNFs and Cloud-based microservices across NFV and cloud infrastructures can enhance service quality, reduce latency, and optimise cost. This can be provided by an orchestration system that can handle cross-ecosystem dependencies. To this end, we implemented Pishahang that is a framework for jointly managing and orchestrating virtual network functions and Cloud-based microservices. During the demo, we deploy several complex services to demonstrate features provided by Pishahang to support management and orchestration of complex services.}}, author = {{Razzaghi Kouchaksaraei, Hadi and Dierich, Tobias and Karl, Holger}}, location = {{Montreal, Canada}}, title = {{{Pishahang: Joint Orchestration of Network Function Chains and Distributed Cloud Applications}}}, year = {{2018}}, } @inproceedings{3265, abstract = {{We present CLARC (Cryptographic Library for Anonymous Reputation and Credentials), an anonymous credentials system (ACS) combined with an anonymous reputation system. Using CLARC, users can receive attribute-based credentials from issuers. They can efficiently prove that their credentials satisfy complex (access) policies in a privacy-preserving way. This implements anonymous access control with complex policies. Furthermore, CLARC is the first ACS that is combined with an anonymous reputation system where users can anonymously rate services. A user who gets access to a service via a credential, also anonymously receives a review token to rate the service. If a user creates more than a single rating, this can be detected by anyone, preventing users from spamming ratings to sway public opinion. To evaluate feasibility of our construction, we present an open-source prototype implementation.}}, author = {{Bemmann, Kai and Blömer, Johannes and Bobolz, Jan and Bröcher, Henrik and Diemert, Denis Pascal and Eidens, Fabian and Eilers, Lukas and Haltermann, Jan Frederik and Juhnke, Jakob and Otour, Burhan and Porzenheim, Laurens Alexander and Pukrop, Simon and Schilling, Erik and Schlichtig, Michael and Stienemeier, Marcel}}, booktitle = {{Proceedings of the 13th International Conference on Availability, Reliability and Security - ARES '18}}, isbn = {{978-1-4503-6448-5}}, location = {{Hamburg, Germany}}, publisher = {{ACM}}, title = {{{Fully-Featured Anonymous Credentials with Reputation System}}}, doi = {{10.1145/3230833.3234517}}, year = {{2018}}, } @inproceedings{3345, abstract = {{Dynamically steering flows through virtualized net- work function instances is a key enabler for elastic, on-demand deployments of virtualized network functions. This becomes par- ticular challenging when stateful functions are involved, necessi- tating state management. The problem with existing solutions is that they typically embrace state migration and flow rerouting jointly, imposing a huge set of requirements on the on-boarded VNFs, e.g., solution-specific state management interfaces. In this paper, we introduce the seamless handover proto- col (SHarP). It provides an easy-to-use, loss-less, and order- preserving flow rerouting mechanism that is not fixed to a single state management approach. This allows VNF vendors to implement or use the state management solution of their choice. SHarP supports these solutions with additional information when flows are migrated. Further, we show how SHarP significantly reduces the buffer usage at a central (SDN) controller, which is a typical bottleneck in existing solutions. Our experiments show that SHarP uses a constant amount of controller buffer, irrespective of the time taken to migrate the VNF state.}}, author = {{Peuster, Manuel and Küttner, Hannes and Karl, Holger}}, booktitle = {{4th IEEE International Conference on Network Softwarization (NetSoft 2018)}}, location = {{Montreal}}, title = {{{ Let the state follow its flows: An SDN-based flow handover protocol to support state migration}}}, doi = {{10.1109/NETSOFT.2018.8460007}}, year = {{2018}}, } @inproceedings{3346, abstract = {{Developing a virtualized network service does not only involve the implementation and configuration of the network functions it is composed of but also its integration and test with management solutions that will control the service in its production environment. These integration tasks require testbeds that offer the needed network function virtualization infrastructure~(NFVI), like OpenStack, introducing a lot of management and maintenance overheads. Such testbed setups become even more complicated when the multi point-of-presence~(PoP) case, with multiple infrastructure installations, is considered. In this demo, we showcase an emulation platform that executes containerized network services in user-defined multi-PoP topologies. The platform does not only allow network service developers to locally test their services but also to connect real-world management and orchestration solutions to the emulated PoPs. During our interactive demonstration we focus on the integration between the emulated infrastructure and state-of-the-art orchestration solutions like SONATA or OSM.}}, author = {{Peuster, Manuel and Kampmeyer, Johannes and Karl, Holger}}, booktitle = {{4th IEEE International Conference on Network Softwarization (NetSoft 2018)}}, location = {{Montreal}}, title = {{{Containernet 2.0: A Rapid Prototyping Platform for Hybrid Service Function Chains}}}, doi = {{10.1109/NETSOFT.2018.8459905}}, year = {{2018}}, } @inproceedings{3347, abstract = {{Management and orchestration~(MANO) systems are the key components of future large-scale NFV environments. They will manage resources of hundreds or even thousands of NFV infrastructure installations, so called points of presence~(PoP). Such scenarios need to be automatically tested during the development phase of a MANO system. This task becomes very challenging because large-scale NFV testbeds are hard to maintain, too expensive, or simply not available. In this paper, we present a multi-PoP NFV infrastructure emulation platform that enables automated, large-scale testing of MANO stacks. We show that our platform can easily emulate hundreds of PoPs on a single physical machine and reduces the setup time of a test PoP by a factor of 232x compared to a DevStack-based test PoP installation. Further, we present a case study in which we test ETSI's Open Source MANO~(OSM) against our proposed system to gain insights about OSM's behaviour in large-scale NFV deployments.}}, author = {{Peuster, Manuel and Marchetti, Michael and Garcia de Blas, Gerado and Karl, Holger}}, booktitle = {{European Conference on Networks and Communications (EuCNC)}}, location = {{Ljubljana}}, title = {{{Emulation-based Smoke Testing of NFV Orchestrators in Large Multi-PoP Environments}}}, doi = {{10.1109/EuCNC.2018.8442701}}, year = {{2018}}, } @article{3510, abstract = {{Automated machine learning (AutoML) seeks to automatically select, compose, and parametrize machine learning algorithms, so as to achieve optimal performance on a given task (dataset). Although current approaches to AutoML have already produced impressive results, the field is still far from mature, and new techniques are still being developed. In this paper, we present ML-Plan, a new approach to AutoML based on hierarchical planning. To highlight the potential of this approach, we compare ML-Plan to the state-of-the-art frameworks Auto-WEKA, auto-sklearn, and TPOT. In an extensive series of experiments, we show that ML-Plan is highly competitive and often outperforms existing approaches.}}, author = {{Mohr, Felix and Wever, Marcel Dominik and Hüllermeier, Eyke}}, issn = {{1573-0565}}, journal = {{Machine Learning}}, keywords = {{AutoML, Hierarchical Planning, HTN planning, ML-Plan}}, location = {{Dublin, Ireland}}, pages = {{1495--1515}}, publisher = {{Springer}}, title = {{{ML-Plan: Automated Machine Learning via Hierarchical Planning}}}, doi = {{10.1007/s10994-018-5735-z}}, year = {{2018}}, } @inproceedings{3552, author = {{Mohr, Felix and Wever, Marcel Dominik and Hüllermeier, Eyke}}, booktitle = {{Proceedings of the Symposium on Intelligent Data Analysis}}, location = {{‘s-Hertogenbosch, the Netherlands}}, title = {{{Reduction Stumps for Multi-Class Classification}}}, doi = {{10.1007/978-3-030-01768-2_19}}, year = {{2018}}, } @article{3740, abstract = {{Oblique propagation of semi-guided waves across slab waveguide structures with bent corners is investigated. A critical angle can be defined beyond which all radiation losses are suppressed. Additionally an increase of the curvature radius of the bends also leads to low-loss configurations for incidence angles below that critical angle. A combination of two bent corner systems represents a step-like structure, behaving like a Fabry-Perot interferometer, with two partial reflectors separated by the vertical height between the horizontal slabs. We numerically analyse typical high-index-contrast Si/SiO2 structures for their reflectance and transmittance properties. When increasing the curvature radius the resonant effect becomes less relevant such that full transmittance is reached with less critical conditions on the vertical distance or the incidence angle. For practical interest 3-D problems are considered, where the structures are excited by the fundamental mode of a wide, shallow rib waveguide. High transmittance levels can be observed also for these 3-D configurations depending on the width of the rib.}}, author = {{Ebers, Lena and Hammer, Manfred and Förstner, Jens}}, journal = {{Optics Express}}, keywords = {{tet_topic_waveguide}}, number = {{14}}, pages = {{18621--18632}}, publisher = {{OSA Publishing}}, title = {{{Oblique incidence of semi-guided planar waves on slab waveguide steps: effects of rounded edges}}}, doi = {{10.1364/OE.26.018621}}, volume = {{26}}, year = {{2018}}, } @inproceedings{3852, abstract = {{In automated machine learning (AutoML), the process of engineering machine learning applications with respect to a specific problem is (partially) automated. Various AutoML tools have already been introduced to provide out-of-the-box machine learning functionality. More specifically, by selecting machine learning algorithms and optimizing their hyperparameters, these tools produce a machine learning pipeline tailored to the problem at hand. Except for TPOT, all of these tools restrict the maximum number of processing steps of such a pipeline. However, as TPOT follows an evolutionary approach, it suffers from performance issues when dealing with larger datasets. In this paper, we present an alternative approach leveraging a hierarchical planning to configure machine learning pipelines that are unlimited in length. We evaluate our approach and find its performance to be competitive with other AutoML tools, including TPOT.}}, author = {{Wever, Marcel Dominik and Mohr, Felix and Hüllermeier, Eyke}}, booktitle = {{ICML 2018 AutoML Workshop}}, keywords = {{automated machine learning, complex pipelines, hierarchical planning}}, location = {{Stockholm, Sweden}}, title = {{{ML-Plan for Unlimited-Length Machine Learning Pipelines}}}, year = {{2018}}, } @article{3152, abstract = {{To adapt to continuously changing workloads in networks, components of the running network services may need to be replicated (scaling the network service) and allocated to physical resources (placement) dynamically, also necessitating dynamic re-routing of flows between service components. In this paper, we propose JASPER, a fully automated approach to jointly optimizing scaling, placement, and routing for complex network services, consisting of multiple (virtualized) components. JASPER handles multiple network services that share the same substrate network; services can be dynamically added or removed and dynamic workload changes are handled. Our approach lets service designers specify their services on a high level of abstraction using service templates. JASPER automatically makes scaling, placement and routing decisions, enabling quick reaction to changes. We formalize the problem, analyze its complexity, and develop two algorithms to solve it. Extensive empirical results show the applicability and effectiveness of the proposed approach.}}, author = {{Dräxler, Sevil and Karl, Holger and Mann, Zoltan Adam}}, journal = {{IEEE Transactions on Network and Service Management}}, publisher = {{IEEE}}, title = {{{JASPER: Joint Optimization of Scaling, Placement, and Routing of Virtual Network Services}}}, doi = {{10.1109/TNSM.2018.2846572}}, year = {{2018}}, } @inproceedings{2109, abstract = {{In multinomial classification, reduction techniques are commonly used to decompose the original learning problem into several simpler problems. For example, by recursively bisecting the original set of classes, so-called nested dichotomies define a set of binary classification problems that are organized in the structure of a binary tree. In contrast to the existing one-shot heuristics for constructing nested dichotomies and motivated by recent work on algorithm configuration, we propose a genetic algorithm for optimizing the structure of such dichotomies. A key component of this approach is the proposed genetic representation that facilitates the application of standard genetic operators, while still supporting the exchange of partial solutions under recombination. We evaluate the approach in an extensive experimental study, showing that it yields classifiers with superior generalization performance.}}, author = {{Wever, Marcel Dominik and Mohr, Felix and Hüllermeier, Eyke}}, booktitle = {{Proceedings of the Genetic and Evolutionary Computation Conference, GECCO 2018, Kyoto, Japan, July 15-19, 2018}}, keywords = {{Classification, Hierarchical Decomposition, Indirect Encoding}}, location = {{Kyoto, Japan}}, publisher = {{ACM}}, title = {{{Ensembles of Evolved Nested Dichotomies for Classification}}}, doi = {{10.1145/3205455.3205562}}, year = {{2018}}, }