Dipl.-Inf. Steffen Gebert

• Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks Raffeck, Simon; Geißler, Stefan; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias in 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA) (2022).
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  IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.

  @inproceedings{info3-inproceedings-2022-5, abstract = {IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.}, author = {Raffeck, Simon and Geißler, Stefan and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA)}, keywords = {can}, month = 4, title = {Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks}, year = 2022 }

  %0 Conference Paper %1 info3-inproceedings-2022-5 %A Raffeck, Simon %A Geißler, Stefan %A Krolikowski, Michael %A Gebert, Steffen %A Hoßfeld, Tobias %B 2nd IFIP/IEEE International workshop on Fully-Flexible Internet Architectures and Protocols for the Next-Generation Tactile Internet (FlexNGIA) %D 2022 %T Data Usage in IoT: A Characterization of GTP Tunnels in M2M Mobile Networks %X IoT and M2M devices have seen a significant growth in usage and deployment over the last years. Gaining insight into device and data usage behavior exhibited by the participants of mobile networks is elementary for MNO and MVNO to scale their networks and provide a reliable service. This work aims to make use of its first of a kind dataset, spanning multiple countries and MNO, to provide a detailed characterization of GTP tunnels and devices. To this end, general statistics are used to describe the observed data traffic focusing on the distribution of the tunnel duration and volume as well as periodic device behavior. An approximate metric is introduced to analyze the periodicity and synchronicity of IoT devices. Lastly, we publish the data investigated in this work and provide a large scale dataset on the data usage behavior of IoT devices to interested researchers.
• Anonymized GTP Tunnel Trace in Mobile IoT Raffeck, Simon; Geißler, Stefan; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias (2022, February).
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  Extensive dataset containing one whole month of create and delete events as well as the total, received, and transmitted volume of devices. We obtained data tunnel related events and volume values over 30 days in October 2021. In total the dataset contains a sample of 500000 unique devices that generate 155 million individual data tunnels.

  @misc{info3-misc-2022-1, abstract = {Extensive dataset containing one whole month of create and delete events as well as the total, received, and transmitted volume of devices. We obtained data tunnel related events and volume values over 30 days in October 2021. In total the dataset contains a sample of 500000 unique devices that generate 155 million individual data tunnels.}, author = {Raffeck, Simon and Geißler, Stefan and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, howpublished = {https://zenodo.org/record/6045708}, keywords = {can}, month = 2, title = {Anonymized GTP Tunnel Trace in Mobile IoT}, year = 2022 }

  %0 Generic %1 info3-misc-2022-1 %A Raffeck, Simon %A Geißler, Stefan %A Krolikowski, Michael %A Gebert, Steffen %A Hoßfeld, Tobias %D 2022 %T Anonymized GTP Tunnel Trace in Mobile IoT %X Extensive dataset containing one whole month of create and delete events as well as the total, received, and transmitted volume of devices. We obtained data tunnel related events and volume values over 30 days in October 2021. In total the dataset contains a sample of 500000 unique devices that generate 155 million individual data tunnels.

• Signaling Traffic in Internet-of-Things Mobile Networks Geissler, Stefan; Wamser, Florian; Bauer, Wolfang; Krolikowski, Michael; Gebert, Steffen; Hoßfeld, Tobias in IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) (2021).
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  The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.

  @inproceedings{info3-inproceedings-2021-1, abstract = {The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.}, address = {Bordeaux, France (Virtual Conference)}, author = {Geissler, Stefan and Wamser, Florian and Bauer, Wolfang and Krolikowski, Michael and Gebert, Steffen and Hoßfeld, Tobias}, booktitle = {IFIP/IEEE International Symposium on Integrated Network Management (IM 2021)}, keywords = {can}, month = 5, title = {Signaling Traffic in Internet-of-Things Mobile Networks}, year = 2021 }

  %0 Conference Paper %1 info3-inproceedings-2021-1 %A Geissler, Stefan %A Wamser, Florian %A Bauer, Wolfang %A Krolikowski, Michael %A Gebert, Steffen %A Hoßfeld, Tobias %B IFIP/IEEE International Symposium on Integrated Network Management (IM 2021) %C Bordeaux, France (Virtual Conference) %D 2021 %T Signaling Traffic in Internet-of-Things Mobile Networks %X The Internet of Things (IoT) is expected to play an increasingly important role in next-generation mobile networks. Detailed knowledge of this type of traffic and the associated signaling in those networks is of interest to operators and standardization in order to run these networks successfully. The aim of this study is to characterize IoT signaling traffic for mobile communication networks (i) from a network operator’s point of view, (ii) at device level, and (iii) for the establishment of data connections. General statistics on signaling and device behavior, such as the observed IoT traffic volume and message composition, are given before device classes with statistically different signaling behavior are identified. Finally, by characterizing the aggre- gated signaling traffic, we show that the Markov assumption, widespread in standardization and literature, regarding the aggregated arrival process for data connections does not apply in reality.

• Architectures for Softwarized Networks and their Performance Evaluation Gebert, Steffen PhD thesis, University of Wuerzburg. (2017, June).
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  @phdthesis{info3-dissertation-2017-1, author = {Gebert, Steffen}, keywords = {sys:hidden:supervisor:phuoc.tran-gia}, month = 6, school = {University of Wuerzburg}, title = {Architectures for Softwarized Networks and their Performance Evaluation}, year = 2017 }

  %0 Thesis %1 info3-dissertation-2017-1 %A Gebert, Steffen %D 2017 %T Architectures for Softwarized Networks and their Performance Evaluation
• SDN and NFV as Enabler for the Distributed Network Cloud Hoffmann, Marco; Jarschel, Michael; Pries, Rastin; Schneider, Peter; Jukan, Admela; Bziuk, Wolfgang; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc in Mobile Networks and Applications (2017).
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  @article{info3-article-2017-8, author = {Hoffmann, Marco and Jarschel, Michael and Pries, Rastin and Schneider, Peter and Jukan, Admela and Bziuk, Wolfgang and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {Mobile Networks and Applications}, keywords = {sys:hidden:article}, title = {SDN and NFV as Enabler for the Distributed Network Cloud}, year = 2017 }

  %0 Journal Article %1 info3-article-2017-8 %A Hoffmann, Marco %A Jarschel, Michael %A Pries, Rastin %A Schneider, Peter %A Jukan, Admela %A Bziuk, Wolfgang %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %D 2017 %J Mobile Networks and Applications %T SDN and NFV as Enabler for the Distributed Network Cloud
• A Discrete-Time Model for Optimizing the Processing Time of Virtualized Network Functions Zinner, Thomas; Geissler, Stefan; Lange, Stanislav; Gebert, Steffen; Seufert, Michael; Tran-Gia, Phuoc in Computer Networks (2017). 125 4–14.
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  The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees of adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are interrupt moderation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either for low latencies or low CPU overhead for processing of network traffic. In this work, an analytical model that allows the computation of relevant performance metrics like packet processing time and packet loss for generic virtualized network functions running on commodity hardware is presented. Based on this model, impact factors like average packet interarrival time, interarrival time distribution, and duration of the interrupt aggregation interval are studied. Furthermore, we significantly improve the computational tractability of this discrete-time model by proving and leveraging a property regarding its limit behavior. We also demonstrate that using this property does not affect the accuracy of the model in the context of realistic parameter combinations. Finally, the improved runtime for numerical evaluations allows administrators to dynamically adapt their interrupt mitigation settings to changing network conditions by recalculating optimal parameters.

  @article{info3-article-2017-1, abstract = {The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees of adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are interrupt moderation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either for low latencies or low CPU overhead for processing of network traffic. In this work, an analytical model that allows the computation of relevant performance metrics like packet processing time and packet loss for generic virtualized network functions running on commodity hardware is presented. Based on this model, impact factors like average packet interarrival time, interarrival time distribution, and duration of the interrupt aggregation interval are studied. Furthermore, we significantly improve the computational tractability of this discrete-time model by proving and leveraging a property regarding its limit behavior. We also demonstrate that using this property does not affect the accuracy of the model in the context of realistic parameter combinations. Finally, the improved runtime for numerical evaluations allows administrators to dynamically adapt their interrupt mitigation settings to changing network conditions by recalculating optimal parameters.}, author = {Zinner, Thomas and Geissler, Stefan and Lange, Stanislav and Gebert, Steffen and Seufert, Michael and Tran-Gia, Phuoc}, journal = {Computer Networks}, keywords = {sys:hidden:article}, pages = {4-14}, title = {A Discrete-Time Model for Optimizing the Processing Time of Virtualized Network Functions}, volume = 125, year = 2017 }

  %0 Journal Article %1 info3-article-2017-1 %A Zinner, Thomas %A Geissler, Stefan %A Lange, Stanislav %A Gebert, Steffen %A Seufert, Michael %A Tran-Gia, Phuoc %D 2017 %J Computer Networks %P 4-14 %T A Discrete-Time Model for Optimizing the Processing Time of Virtualized Network Functions %V 125 %X The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees of adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are interrupt moderation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either for low latencies or low CPU overhead for processing of network traffic. In this work, an analytical model that allows the computation of relevant performance metrics like packet processing time and packet loss for generic virtualized network functions running on commodity hardware is presented. Based on this model, impact factors like average packet interarrival time, interarrival time distribution, and duration of the interrupt aggregation interval are studied. Furthermore, we significantly improve the computational tractability of this discrete-time model by proving and leveraging a property regarding its limit behavior. We also demonstrate that using this property does not affect the accuracy of the model in the context of realistic parameter combinations. Finally, the improved runtime for numerical evaluations allows administrators to dynamically adapt their interrupt mitigation settings to changing network conditions by recalculating optimal parameters.
• TableVisor 2.0: Towards Full-Featured, Scalable and Hardware-Independent Multi Table Processing Geissler, Stefan; Gebert, Steffen; Herrnleben, Stefan; Zinner, Thomas; Bauer, Robert; Jarschel, Michael in NetSoft 2017, Best Student Paper Award (2017).
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  Modern Software Defined Networking (SDN) appli- cations rely on sophisticated packet processing. However, there is a mismatch between control plane requirements and data plane capabilities caused by increasing hardware heterogeneity. To overcome this challenge, we propose TableVisor, a proxy-layer for the OpenFlow control channel that enables the flexible and scalable abstraction of multiple physical devices into one emu- lated data plane switch that meets the requirements of the control plane application. TableVisor registers with the SDN controller as a single switch with use-case specific capabilities. It translates the instructions and rules from the control application towards the appropriate physical device where they are executed. In this paper, we present the updated architecture and functionality of TableVisor as well as first evaluation results based on testbed experiments.

  @inproceedings{info3-inproceedings-2017-4, abstract = {Modern Software Defined Networking (SDN) appli- cations rely on sophisticated packet processing. However, there is a mismatch between control plane requirements and data plane capabilities caused by increasing hardware heterogeneity. To overcome this challenge, we propose TableVisor, a proxy-layer for the OpenFlow control channel that enables the flexible and scalable abstraction of multiple physical devices into one emu- lated data plane switch that meets the requirements of the control plane application. TableVisor registers with the SDN controller as a single switch with use-case specific capabilities. It translates the instructions and rules from the control application towards the appropriate physical device where they are executed. In this paper, we present the updated architecture and functionality of TableVisor as well as first evaluation results based on testbed experiments.}, author = {Geissler, Stefan and Gebert, Steffen and Herrnleben, Stefan and Zinner, Thomas and Bauer, Robert and Jarschel, Michael}, booktitle = {NetSoft 2017, Best Student Paper Award}, keywords = {sendate}, month = 2, title = {TableVisor 2.0: Towards Full-Featured, Scalable and Hardware-Independent Multi Table Processing}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-4 %A Geissler, Stefan %A Gebert, Steffen %A Herrnleben, Stefan %A Zinner, Thomas %A Bauer, Robert %A Jarschel, Michael %B NetSoft 2017, Best Student Paper Award %D 2017 %T TableVisor 2.0: Towards Full-Featured, Scalable and Hardware-Independent Multi Table Processing %X Modern Software Defined Networking (SDN) appli- cations rely on sophisticated packet processing. However, there is a mismatch between control plane requirements and data plane capabilities caused by increasing hardware heterogeneity. To overcome this challenge, we propose TableVisor, a proxy-layer for the OpenFlow control channel that enables the flexible and scalable abstraction of multiple physical devices into one emu- lated data plane switch that meets the requirements of the control plane application. TableVisor registers with the SDN controller as a single switch with use-case specific capabilities. It translates the instructions and rules from the control application towards the appropriate physical device where they are executed. In this paper, we present the updated architecture and functionality of TableVisor as well as first evaluation results based on testbed experiments.
• A Priori State Synchronization for Fast Failover of Stateful Firewall VNFs Gray, Nicholas; Lorenz, Class; Müssig, Alexander; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc in Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2017) (2017).
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  Network Functions Virtualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hard- ware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster’s instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability

  @inproceedings{info3-inproceedings-2017-2, abstract = {Network Functions Virtualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hard- ware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster’s instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability}, address = {Göttingen, Germany}, author = {Gray, Nicholas and Lorenz, Class and Müssig, Alexander and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2017)}, keywords = {sardine}, title = {A Priori State Synchronization for Fast Failover of Stateful Firewall VNFs}, year = 2017 }

  %0 Conference Paper %1 info3-inproceedings-2017-2 %A Gray, Nicholas %A Lorenz, Class %A Müssig, Alexander %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %B Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2017) %C Göttingen, Germany %D 2017 %T A Priori State Synchronization for Fast Failover of Stateful Firewall VNFs %X Network Functions Virtualization (NFV) replaces physical middleboxes with software instances running network functions in cloud environments. To support this new paradigm, it is necessary to port the code basis from highly specialized hardware devices to virtual machines running on COTS hard- ware. In order to fully exploit the inherent capabilities of cloud environments it is further necessary to redesign the software to support a large amount of distributed, cooperating function instances instead of single, isolated and monolithic instances. This development can be observed for network functions like stateful firewalling. Until now, available software firewalls lack support for active/active operation in clustered environments, which hinders horizontal scalability. This is due to the fact that the required synchronization of connection states among the cluster’s instances is an impediment that still has to be resolved. Therefore, this work investigates different synchronization strategies and mechanisms, which allow to share connection states among the cluster to maintain scalability and high-availability
• An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement Lorenz, Claas; Hock, David; Scherer, Johann; Durner, Raphael; Kellerer, Wolfgang; Gebert, Steffen; Gray, Nicholas; Zinner, Thomas; Tran-Gia, Phuoc in IEEE Communications Magazine (2017). 55(3) 217–223.
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  In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.

  @article{info3-article-2016-9, abstract = {In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.}, author = {Lorenz, Claas and Hock, David and Scherer, Johann and Durner, Raphael and Kellerer, Wolfgang and Gebert, Steffen and Gray, Nicholas and Zinner, Thomas and Tran-Gia, Phuoc}, journal = {IEEE Communications Magazine}, keywords = {sys:hidden:article}, month = 3, number = 3, pages = {217 - 223}, title = {An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement}, volume = 55, year = 2017 }

  %0 Journal Article %1 info3-article-2016-9 %A Lorenz, Claas %A Hock, David %A Scherer, Johann %A Durner, Raphael %A Kellerer, Wolfgang %A Gebert, Steffen %A Gray, Nicholas %A Zinner, Thomas %A Tran-Gia, Phuoc %D 2017 %J IEEE Communications Magazine %N 3 %P 217 - 223 %T An SDN/NFV-enabled Enterprise Network Architecture Offering Fine-Grained Security Policy Enforcement %V 55 %X In recent years, the number of attacks and threat vectors against enterprise networks have been constantly increasing in numbers and variety. In addition, new challenges arise not only to the level of provided security, but also to the scalability and manageability of the deployed countermeasures such as firewalls and intrusion detection systems. Despite these attacks, the main security systems, e.g., network firewalls, have remained rather unchanged. Due to the tight integration into the physical network’s infrastructure, a dynamic resource allocation to adapt the security measures to the current network conditions is a difficult undertaking. Therefore, in this work, we analyze and compare different architectural design patterns for the integration of SDN/NFV-based security solutions into enterprise networks.

• Performance Evaluation Mechanisms for FlowMod Message Processing in OpenFlow Switches Nguyen-Ngoc, Anh; Lange, Stanislav; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc; Jarschel, Michael in IEEE Sixth International Conference on Communications and Electronics (2016).
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  Network operators can benefit in terms of flexibility, cost, and vendor-independence when adopting the Software Defined Networking (SDN) paradigm. In many scenarios, the SDN controller orders the installation of new flow table entries in the switches it manages. Since such operations are handled in the slow path of the switches, the corresponding processing times constitute an important performance indicator for switches. This work focuses on a comparison of two mechanisms for evaluating the performance of OpenFlow switches with respect to the processing time of FlowMod messages. These mechanisms are characterized by different degrees of accuracy, cost, complexity, and the capability of performing measurements at run time. The first mechanism is based on the Spirent C1 dedicated testing platform, while the other uses a software module for the OpenDaylight controller. We assess their capabilities with respect to the abovementioned characteristics and quantify their accuracy by means of wiretaps that provide a ground truth regarding the measured processing times. By using three different switches in the experiments, it is possible to distinguish between hardware specific side-effects and general phenomena.

  @inproceedings{info3-inproceedings-2016-7, abstract = {Network operators can benefit in terms of flexibility, cost, and vendor-independence when adopting the Software Defined Networking (SDN) paradigm. In many scenarios, the SDN controller orders the installation of new flow table entries in the switches it manages. Since such operations are handled in the slow path of the switches, the corresponding processing times constitute an important performance indicator for switches. This work focuses on a comparison of two mechanisms for evaluating the performance of OpenFlow switches with respect to the processing time of FlowMod messages. These mechanisms are characterized by different degrees of accuracy, cost, complexity, and the capability of performing measurements at run time. The first mechanism is based on the Spirent C1 dedicated testing platform, while the other uses a software module for the OpenDaylight controller. We assess their capabilities with respect to the abovementioned characteristics and quantify their accuracy by means of wiretaps that provide a ground truth regarding the measured processing times. By using three different switches in the experiments, it is possible to distinguish between hardware specific side-effects and general phenomena.}, address = {Ha Long City, Vietnam}, author = {Nguyen-Ngoc, Anh and Lange, Stanislav and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc and Jarschel, Michael}, booktitle = {IEEE Sixth International Conference on Communications and Electronics}, keywords = {sendate}, month = 7, title = {Performance Evaluation Mechanisms for FlowMod Message Processing in OpenFlow Switches}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-7 %A Nguyen-Ngoc, Anh %A Lange, Stanislav %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %A Jarschel, Michael %B IEEE Sixth International Conference on Communications and Electronics %C Ha Long City, Vietnam %D 2016 %T Performance Evaluation Mechanisms for FlowMod Message Processing in OpenFlow Switches %X Network operators can benefit in terms of flexibility, cost, and vendor-independence when adopting the Software Defined Networking (SDN) paradigm. In many scenarios, the SDN controller orders the installation of new flow table entries in the switches it manages. Since such operations are handled in the slow path of the switches, the corresponding processing times constitute an important performance indicator for switches. This work focuses on a comparison of two mechanisms for evaluating the performance of OpenFlow switches with respect to the processing time of FlowMod messages. These mechanisms are characterized by different degrees of accuracy, cost, complexity, and the capability of performing measurements at run time. The first mechanism is based on the Spirent C1 dedicated testing platform, while the other uses a software module for the OpenDaylight controller. We assess their capabilities with respect to the abovementioned characteristics and quantify their accuracy by means of wiretaps that provide a ground truth regarding the measured processing times. By using three different switches in the experiments, it is possible to distinguish between hardware specific side-effects and general phenomena.
• Performance Modeling of Softwarized Network Functions Using Discrete-Time Analysis Gebert, Steffen; Zinner, Thomas; Lange, Stanislav; Schwartz, Christian; Tran-Gia, Phuoc in 28th International Teletraffic Congress (ITC) (2016).
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  The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees for adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are the interrupt mitigation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either lower latencies or lower CPU overhead for processing of network traffic. In this work, an analytical model that allows computing relevant performance metrics like the packet processing time and the packet loss for generic virtualized network functions running on commodity hardware is developed. The applicability of the model is shown by comparing its outcome with measurements conducted in a local testbed. Based on this model, impact factors like the average packet interarrival time, the interarrival time distribution, and the duration of the interrupt aggregation interval are studied.

  @inproceedings{info3-inproceedings-2016-4, abstract = {The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees for adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are the interrupt mitigation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either lower latencies or lower CPU overhead for processing of network traffic. In this work, an analytical model that allows computing relevant performance metrics like the packet processing time and the packet loss for generic virtualized network functions running on commodity hardware is developed. The applicability of the model is shown by comparing its outcome with measurements conducted in a local testbed. Based on this model, impact factors like the average packet interarrival time, the interarrival time distribution, and the duration of the interrupt aggregation interval are studied.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Zinner, Thomas and Lange, Stanislav and Schwartz, Christian and Tran-Gia, Phuoc}, booktitle = {28th International Teletraffic Congress (ITC)}, keywords = {sendate}, month = 9, title = {Performance Modeling of Softwarized Network Functions Using Discrete-Time Analysis}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-4 %A Gebert, Steffen %A Zinner, Thomas %A Lange, Stanislav %A Schwartz, Christian %A Tran-Gia, Phuoc %B 28th International Teletraffic Congress (ITC) %C Würzburg, Germany %D 2016 %T Performance Modeling of Softwarized Network Functions Using Discrete-Time Analysis %X The softwarization of networks promises cost savings and better scalability of network functions by moving functionality from specialized devices into commercial off-the-shelf hardware. Generalized computing hardware offers many degrees for adjustment and tuning, which can affect performance and resource utilization. One of these adjustments are the interrupt mitigation techniques implemented by modern network interface cards and operating systems. Using these, an administrator can optimize either lower latencies or lower CPU overhead for processing of network traffic. In this work, an analytical model that allows computing relevant performance metrics like the packet processing time and the packet loss for generic virtualized network functions running on commodity hardware is developed. The applicability of the model is shown by comparing its outcome with measurements conducted in a local testbed. Based on this model, impact factors like the average packet interarrival time, the interarrival time distribution, and the duration of the interrupt aggregation interval are studied.
• Demonstrating a Personalized Secure-By-Default Bring Your Own Device Solution Based on Software Defined Networking Gebert, Steffen; Zinner, Thomas; Gray, Nicholas; Durner, Raphael; Lorenz, Class; Lange, Stanislav (2016, September).
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  Network virtualization is one classical use-case for Software Defined Networks (SDN). By programmatically instantiating virtual networks, traffic from one or more devices can be separated or connectivity can be established as needed. S- BYOD, which is presented in this demonstration, applies the SDN concept to Bring Your Own Device (BYOD) scenarios and offers personalized virtual networks that are set up and extended on demand. This is done once the user authenticates, activates access to additional applications, or as soon as applications scale out and involve more servers. The described proof-of-concept implementation explores, to what degree an agent-less BYOD solution, based only on SDN, can lower the attack surface by explicit user opt-ins for particular services. Further, an assessment of the number of required rules within the flow tables of switches completes this work.

  @misc{info3-demo-2016-1, abstract = {Network virtualization is one classical use-case for Software Defined Networks (SDN). By programmatically instantiating virtual networks, traffic from one or more devices can be separated or connectivity can be established as needed. S- BYOD, which is presented in this demonstration, applies the SDN concept to Bring Your Own Device (BYOD) scenarios and offers personalized virtual networks that are set up and extended on demand. This is done once the user authenticates, activates access to additional applications, or as soon as applications scale out and involve more servers. The described proof-of-concept implementation explores, to what degree an agent-less BYOD solution, based only on SDN, can lower the attack surface by explicit user opt-ins for particular services. Further, an assessment of the number of required rules within the flow tables of switches completes this work.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Zinner, Thomas and Gray, Nicholas and Durner, Raphael and Lorenz, Class and Lange, Stanislav}, booktitle = {28th International Teletraffic Congress (ITC 28)}, keywords = {sardine}, month = 9, title = {Demonstrating a Personalized Secure-By-Default Bring Your Own Device Solution Based on Software Defined Networking}, year = 2016 }

  %0 Generic %1 info3-demo-2016-1 %A Gebert, Steffen %A Zinner, Thomas %A Gray, Nicholas %A Durner, Raphael %A Lorenz, Class %A Lange, Stanislav %B 28th International Teletraffic Congress (ITC 28) %C Würzburg, Germany %D 2016 %T Demonstrating a Personalized Secure-By-Default Bring Your Own Device Solution Based on Software Defined Networking %X Network virtualization is one classical use-case for Software Defined Networks (SDN). By programmatically instantiating virtual networks, traffic from one or more devices can be separated or connectivity can be established as needed. S- BYOD, which is presented in this demonstration, applies the SDN concept to Bring Your Own Device (BYOD) scenarios and offers personalized virtual networks that are set up and extended on demand. This is done once the user authenticates, activates access to additional applications, or as soon as applications scale out and involve more servers. The described proof-of-concept implementation explores, to what degree an agent-less BYOD solution, based only on SDN, can lower the attack surface by explicit user opt-ins for particular services. Further, an assessment of the number of required rules within the flow tables of switches completes this work.
• Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval Gebert, Steffen; Zinner, Thomas; Lange, Stanislav; Schwartz, Christian; Tran-Gia, Phuoc (2016).
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  @techreport{info3-techreport-2016-1, author = {Gebert, Steffen and Zinner, Thomas and Lange, Stanislav and Schwartz, Christian and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 6, number = 498, title = {Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval}, year = 2016 }

  %0 Report %1 info3-techreport-2016-1 %A Gebert, Steffen %A Zinner, Thomas %A Lange, Stanislav %A Schwartz, Christian %A Tran-Gia, Phuoc %D 2016 %N 498 %T Discrete-Time Analysis: Deriving the Distribution of the Number of Events in an Arbitrarily Distributed Interval
• ZOOM: Lightweight SDN-based Elephant Detection Gebert, Steffen; Geissler, Stefan; Zinner, Thomas; Nguyen-Ngoc, Anh; Lange, Stanislav; Tran-Gia, Phuoc in First International Workshop on Programmability for Cloud Networks and Applications (PROCON) (2016).
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  Software Defined Networking (SDN) offers a holistic view of the network through a centralized control plane. Consequently, routing decisions can be made based on global knowledge about the network topology as well as its current state. As long living flows are suitable candidates for rerouting, their detection is crucial for efficient flow based traffic management. This work proposes the ZOOM algorithm for elephant detection in SDN networks. To this end, ZOOM follows a very lightweight approach that only uses packet counters implemented by OpenFlow switches and thus does not require any additional hardware. By exploiting this feature of OpenFlow switches, ZOOM allows lightweight and cost-effective elephant detection.

  @inproceedings{info3-inproceedings-2016-8, abstract = {Software Defined Networking (SDN) offers a holistic view of the network through a centralized control plane. Consequently, routing decisions can be made based on global knowledge about the network topology as well as its current state. As long living flows are suitable candidates for rerouting, their detection is crucial for efficient flow based traffic management. This work proposes the ZOOM algorithm for elephant detection in SDN networks. To this end, ZOOM follows a very lightweight approach that only uses packet counters implemented by OpenFlow switches and thus does not require any additional hardware. By exploiting this feature of OpenFlow switches, ZOOM allows lightweight and cost-effective elephant detection.}, address = {Würzburg, Germany}, author = {Gebert, Steffen and Geissler, Stefan and Zinner, Thomas and Nguyen-Ngoc, Anh and Lange, Stanislav and Tran-Gia, Phuoc}, booktitle = {First International Workshop on Programmability for Cloud Networks and Applications (PROCON)}, keywords = {sardine}, month = 9, title = {ZOOM: Lightweight SDN-based Elephant Detection}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-8 %A Gebert, Steffen %A Geissler, Stefan %A Zinner, Thomas %A Nguyen-Ngoc, Anh %A Lange, Stanislav %A Tran-Gia, Phuoc %B First International Workshop on Programmability for Cloud Networks and Applications (PROCON) %C Würzburg, Germany %D 2016 %T ZOOM: Lightweight SDN-based Elephant Detection %X Software Defined Networking (SDN) offers a holistic view of the network through a centralized control plane. Consequently, routing decisions can be made based on global knowledge about the network topology as well as its current state. As long living flows are suitable candidates for rerouting, their detection is crucial for efficient flow based traffic management. This work proposes the ZOOM algorithm for elephant detection in SDN networks. To this end, ZOOM follows a very lightweight approach that only uses packet counters implemented by OpenFlow switches and thus does not require any additional hardware. By exploiting this feature of OpenFlow switches, ZOOM allows lightweight and cost-effective elephant detection.
• Performance Modeling of Softwarized Network Functions using Discrete-Time Analysis Gebert, Steffen (2016, August 31).
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  @presentation{info3-presentation-2016-6, address = {Fachgruppentagung ITG 5.2.1, Technische Universität Hamburg-Harburg}, author = {Gebert, Steffen}, keywords = {sendate}, month = 8, title = {Performance Modeling of Softwarized Network Functions using Discrete-Time Analysis}, year = 2016 }

  %0 Generic %1 info3-presentation-2016-6 %A Gebert, Steffen %C Fachgruppentagung ITG 5.2.1, Technische Universität Hamburg-Harburg %D 2016 %T Performance Modeling of Softwarized Network Functions using Discrete-Time Analysis
• Processing Time Comparison of a Hardware-Based Firewall and its Virtualized Counterpart Gebert, Steffen; Müssig, Alexander; Lange, Stanislav; Zinner, Thomas; Gray, Nicholas; Tran-Gia, Phuoc in 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016) (2016).
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  @inproceedings{info3-inproceedings-2016-19, address = {Abu Dhabi, United Arab Emirates}, author = {Gebert, Steffen and Müssig, Alexander and Lange, Stanislav and Zinner, Thomas and Gray, Nicholas and Tran-Gia, Phuoc}, booktitle = {8th EAI International Conference on Mobile Networks and Management (MONAMI 2016)}, keywords = {sardine}, month = 10, title = {Processing Time Comparison of a Hardware-Based Firewall and its Virtualized Counterpart}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-19 %A Gebert, Steffen %A Müssig, Alexander %A Lange, Stanislav %A Zinner, Thomas %A Gray, Nicholas %A Tran-Gia, Phuoc %B 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016) %C Abu Dhabi, United Arab Emirates %D 2016 %T Processing Time Comparison of a Hardware-Based Firewall and its Virtualized Counterpart
• Simulation Framework for Distributed SDN-Controller Architectures in OMNeT++ Gray, Nicholas; Zinner, Thomas; Gebert, Steffen; Tran-Gia, Phuoc in 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016) (2016).
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  SDN introduces the seperation of network control and network data plane. The control plane is removed from distributed network entities and logically centralized as the SDN controller. To provide resilience and performance such a logically centralized controller may again be physically distributed. Scenarios featuring distributed controller architectures include data center deployments, where controller instances synchronize states on small distances and delays, or continental WAN deployments with long distances and delays between controllers. The contribution of this paper is an OMNET++ based simulation framework for assessing the performance of distributed SDN controller architectures. Relevant protocols and controller applications are modelled with a high level of detail. Further, an exemplary implementation of two different controller architectures, namely Hyperflow and Kandoo, is included. Initial results based on the provided implementations are presented.

  @inproceedings{info3-inproceedings-2016-20, abstract = {SDN introduces the seperation of network control and network data plane. The control plane is removed from distributed network entities and logically centralized as the SDN controller. To provide resilience and performance such a logically centralized controller may again be physically distributed. Scenarios featuring distributed controller architectures include data center deployments, where controller instances synchronize states on small distances and delays, or continental WAN deployments with long distances and delays between controllers. The contribution of this paper is an OMNET++ based simulation framework for assessing the performance of distributed SDN controller architectures. Relevant protocols and controller applications are modelled with a high level of detail. Further, an exemplary implementation of two different controller architectures, namely Hyperflow and Kandoo, is included. Initial results based on the provided implementations are presented.}, address = {Abu Dhabi, United Arab Emirates}, author = {Gray, Nicholas and Zinner, Thomas and Gebert, Steffen and Tran-Gia, Phuoc}, booktitle = {8th EAI International Conference on Mobile Networks and Management (MONAMI 2016)}, keywords = {sendate}, month = 10, title = {Simulation Framework for Distributed SDN-Controller Architectures in OMNeT++}, year = 2016 }

  %0 Conference Paper %1 info3-inproceedings-2016-20 %A Gray, Nicholas %A Zinner, Thomas %A Gebert, Steffen %A Tran-Gia, Phuoc %B 8th EAI International Conference on Mobile Networks and Management (MONAMI 2016) %C Abu Dhabi, United Arab Emirates %D 2016 %T Simulation Framework for Distributed SDN-Controller Architectures in OMNeT++ %X SDN introduces the seperation of network control and network data plane. The control plane is removed from distributed network entities and logically centralized as the SDN controller. To provide resilience and performance such a logically centralized controller may again be physically distributed. Scenarios featuring distributed controller architectures include data center deployments, where controller instances synchronize states on small distances and delays, or continental WAN deployments with long distances and delays between controllers. The contribution of this paper is an OMNET++ based simulation framework for assessing the performance of distributed SDN controller architectures. Relevant protocols and controller applications are modelled with a high level of detail. Further, an exemplary implementation of two different controller architectures, namely Hyperflow and Kandoo, is included. Initial results based on the provided implementations are presented.

• Agile Management of Software Based Networks Gebert, Steffen; Schwartz, Christian; Zinner, Thomas; Tran-Gia, Phuoc (2015).
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  @techreport{info3-techreport-2015-267, author = {Gebert, Steffen and Schwartz, Christian and Zinner, Thomas and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 1, number = 493, title = {Agile Management of Software Based Networks}, year = 2015 }

  %0 Report %1 info3-techreport-2015-267 %A Gebert, Steffen %A Schwartz, Christian %A Zinner, Thomas %A Tran-Gia, Phuoc %D 2015 %N 493 %T Agile Management of Software Based Networks
• Investigating Isolation between Virtual Networks in Case of Congestion for a Pronto 3290 Switch Nguyen-Ngoc, Anh; Lange, Stanislav; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc; Jarschel, Michael in Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2015) (2015).
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  Resource isolation between virtual networks is one of the key features of network virtualization. It is typically realized by configuring queues with specific rate guarantees on the egress ports of the network devices. The drawback of this architectural choice, however, is that traffic from several ingress ports may result in congestion on an egress port. Hence, the question arises to which extent isolation between virtual networks is realized in state-of-the-art hardware. This work aims at investigating whether congestion within one virtual network may affect the throughput performance of another virtual network. For that, measurements in a local testbed using a Pronto 3290 switch running an OpenFlow-enabling Pica8 firmware are performed.

  @inproceedings{info3-inproceedings-2015-508, abstract = {Resource isolation between virtual networks is one of the key features of network virtualization. It is typically realized by configuring queues with specific rate guarantees on the egress ports of the network devices. The drawback of this architectural choice, however, is that traffic from several ingress ports may result in congestion on an egress port. Hence, the question arises to which extent isolation between virtual networks is realized in state-of-the-art hardware. This work aims at investigating whether congestion within one virtual network may affect the throughput performance of another virtual network. For that, measurements in a local testbed using a Pronto 3290 switch running an OpenFlow-enabling Pica8 firmware are performed.}, address = {Cottbus, Germany}, author = {Nguyen-Ngoc, Anh and Lange, Stanislav and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc and Jarschel, Michael}, booktitle = {Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2015)}, keywords = {saser-siegfried}, month = 3, title = {Investigating Isolation between Virtual Networks in Case of Congestion for a Pronto 3290 Switch}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-508 %A Nguyen-Ngoc, Anh %A Lange, Stanislav %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %A Jarschel, Michael %B Workshop on Software-Defined Networking and Network Function Virtualization for Flexible Network Management (SDNFlex 2015) %C Cottbus, Germany %D 2015 %T Investigating Isolation between Virtual Networks in Case of Congestion for a Pronto 3290 Switch %X Resource isolation between virtual networks is one of the key features of network virtualization. It is typically realized by configuring queues with specific rate guarantees on the egress ports of the network devices. The drawback of this architectural choice, however, is that traffic from several ingress ports may result in congestion on an egress port. Hence, the question arises to which extent isolation between virtual networks is realized in state-of-the-art hardware. This work aims at investigating whether congestion within one virtual network may affect the throughput performance of another virtual network. For that, measurements in a local testbed using a Pronto 3290 switch running an OpenFlow-enabling Pica8 firmware are performed.
• Investigating the Impact of Network Topology on the Processing Times of SDN Controllers Metter, Christopher; Gebert, Steffen; Lange, Stanislav; Zinner, Thomas; Tran-Gia, Phuoc; Jarschel, Michael in Seventh IFIP/IEEE International Workshop on Management of the Future Internet (2015).
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  Software Defined Networking (SDN) introduces the concept of logically-centralized controllers in charge of managing the forwarding behavior of network elements. The new possibilities enabled through the centralization of control logic come with a certain risk: The controller might become a performance bottleneck. Therefore, ensuring sufficient controller performance is one of the crucial tasks prior to a successful SDN deployment. Furthermore, fine-grained traffic engineering, e.g., to achieve higher link utilization, results in a higher frequency of requests that are sent to the controller, which leads to an increased controller load. It is therefore important to analyze the capabilities of SDN controllers prior to deployment. This paper investigates two software implementations, the OpenDaylight and Ryu controllers. The control message throughput of different controllers has been studied several times already; however, it is not yet known what influence the number and topology of connected switches have. This paper investigates this influence in detail for a fat-tree data center topology and a WAN topology as well as 261 topologies with varying characteristics from the Internet Topology Zoo.

  @inproceedings{info3-inproceedings-2015-510, abstract = {Software Defined Networking (SDN) introduces the concept of logically-centralized controllers in charge of managing the forwarding behavior of network elements. The new possibilities enabled through the centralization of control logic come with a certain risk: The controller might become a performance bottleneck. Therefore, ensuring sufficient controller performance is one of the crucial tasks prior to a successful SDN deployment. Furthermore, fine-grained traffic engineering, e.g., to achieve higher link utilization, results in a higher frequency of requests that are sent to the controller, which leads to an increased controller load. It is therefore important to analyze the capabilities of SDN controllers prior to deployment. This paper investigates two software implementations, the OpenDaylight and Ryu controllers. The control message throughput of different controllers has been studied several times already; however, it is not yet known what influence the number and topology of connected switches have. This paper investigates this influence in detail for a fat-tree data center topology and a WAN topology as well as 261 topologies with varying characteristics from the Internet Topology Zoo.}, address = {Ottawa, Canada}, author = {Metter, Christopher and Gebert, Steffen and Lange, Stanislav and Zinner, Thomas and Tran-Gia, Phuoc and Jarschel, Michael}, booktitle = {Seventh IFIP/IEEE International Workshop on Management of the Future Internet}, keywords = {saser-siegfried}, month = 5, title = {Investigating the Impact of Network Topology on the Processing Times of SDN Controllers}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-510 %A Metter, Christopher %A Gebert, Steffen %A Lange, Stanislav %A Zinner, Thomas %A Tran-Gia, Phuoc %A Jarschel, Michael %B Seventh IFIP/IEEE International Workshop on Management of the Future Internet %C Ottawa, Canada %D 2015 %T Investigating the Impact of Network Topology on the Processing Times of SDN Controllers %X Software Defined Networking (SDN) introduces the concept of logically-centralized controllers in charge of managing the forwarding behavior of network elements. The new possibilities enabled through the centralization of control logic come with a certain risk: The controller might become a performance bottleneck. Therefore, ensuring sufficient controller performance is one of the crucial tasks prior to a successful SDN deployment. Furthermore, fine-grained traffic engineering, e.g., to achieve higher link utilization, results in a higher frequency of requests that are sent to the controller, which leads to an increased controller load. It is therefore important to analyze the capabilities of SDN controllers prior to deployment. This paper investigates two software implementations, the OpenDaylight and Ryu controllers. The control message throughput of different controllers has been studied several times already; however, it is not yet known what influence the number and topology of connected switches have. This paper investigates this influence in detail for a fat-tree data center topology and a WAN topology as well as 261 topologies with varying characteristics from the Internet Topology Zoo.
• Continuously Delivering Your Network (Short Paper) Gebert, Steffen; Schwartz, Christian; Zinner, Thomas; Tran-Gia, Phuoc in IEEE/IFIP International Symposium on Integrated Network Management (IM) (2015).
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  Softwarization and cloudification of networks through software defined networking and network functions virtualisation promise a new degree of flexibility and agility. By moving logic from device firmware into software applications and applying software development mechanisms, innovation can be introduced with less effort. Concrete ways how to operate and orchestrate such systems are not yet defined. The process of making changes to a controller software or a virtualized network function in a production network without the risk of network disruption is not covered by literature. Complexity of systems brings the risk of unexpected side-effects and has so long been a show-stopper for administrators applying changes to networking devices. This paper suggests the adaption of the successful concept of continuous delivery into the software defined networking world. Test-driven development and automatic acceptance tests demonstrate that the software engineering community already found ways to ensure that changes do not break. Applied to network engineering, the adaption of continuous delivery can be seen as an enabler for risk-free and frequent changes in production infrastructure through push button deployments.

  @inproceedings{info3-inproceedings-2015-512, abstract = {Softwarization and cloudification of networks through software defined networking and network functions virtualisation promise a new degree of flexibility and agility. By moving logic from device firmware into software applications and applying software development mechanisms, innovation can be introduced with less effort. Concrete ways how to operate and orchestrate such systems are not yet defined. The process of making changes to a controller software or a virtualized network function in a production network without the risk of network disruption is not covered by literature. Complexity of systems brings the risk of unexpected side-effects and has so long been a show-stopper for administrators applying changes to networking devices. This paper suggests the adaption of the successful concept of continuous delivery into the software defined networking world. Test-driven development and automatic acceptance tests demonstrate that the software engineering community already found ways to ensure that changes do not break. Applied to network engineering, the adaption of continuous delivery can be seen as an enabler for risk-free and frequent changes in production infrastructure through push button deployments.}, address = {Ottawa, Canada}, author = {Gebert, Steffen and Schwartz, Christian and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {IEEE/IFIP International Symposium on Integrated Network Management (IM)}, keywords = {saser-siegfried}, month = 5, title = {Continuously Delivering Your Network (Short Paper)}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-512 %A Gebert, Steffen %A Schwartz, Christian %A Zinner, Thomas %A Tran-Gia, Phuoc %B IEEE/IFIP International Symposium on Integrated Network Management (IM) %C Ottawa, Canada %D 2015 %T Continuously Delivering Your Network (Short Paper) %X Softwarization and cloudification of networks through software defined networking and network functions virtualisation promise a new degree of flexibility and agility. By moving logic from device firmware into software applications and applying software development mechanisms, innovation can be introduced with less effort. Concrete ways how to operate and orchestrate such systems are not yet defined. The process of making changes to a controller software or a virtualized network function in a production network without the risk of network disruption is not covered by literature. Complexity of systems brings the risk of unexpected side-effects and has so long been a show-stopper for administrators applying changes to networking devices. This paper suggests the adaption of the successful concept of continuous delivery into the software defined networking world. Test-driven development and automatic acceptance tests demonstrate that the software engineering community already found ways to ensure that changes do not break. Applied to network engineering, the adaption of continuous delivery can be seen as an enabler for risk-free and frequent changes in production infrastructure through push button deployments.
• Specialized Heuristics for the Controller Placement Problem in Large Scale SDN Networks Lange, Stanislav; Gebert, Steffen; Spoerhase, Joachim; Rygielski, Piotr; Zinner, Thomas; Kounev, Samuel; Tran-Gia, Phuoc in International Teletraffic Congress (ITC 27) (2015).
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  The Software Defined Networking~(SDN) concept introduces a paradigm shift in the networking world towards an externalized control plane which is logically centralized. When designing an SDN-based WAN architecture, it is of vital importance to find a feasible solution to the controller placement problem, i.e., to decide where to position a limited amount of resources within the network. In addition to time-independent constraints regarding aspects like scalability, resilience, and control plane communication delays, dynamically changing network conditions like traffic patterns or bandwidth demands need to be considered as well. Consequently, such dynamic environments call for a regular and fast recalculation of placements in order to adapt to the current situation in a timely manner. While an exhaustive evaluation of all possible solutions can be performed within a practically feasible time frame for small and medium-sized networks, such an approach is out of scope for large problem instances which have significantly higher time and memory requirements. Therefore, this work investigates a specialized heuristic, which takes into account a particular set of optimization objectives and returns solutions representing the possible trade-offs between them. Due to its low computation time and acceptable margin of error, this heuristic can be employed by automatic decision systems operating in dynamic environments.

  @inproceedings{info3-inproceedings-2015-519, abstract = {The Software Defined Networking (SDN) concept introduces a paradigm shift in the networking world towards an externalized control plane which is logically centralized. When designing an SDN-based WAN architecture, it is of vital importance to find a feasible solution to the controller placement problem, i.e., to decide where to position a limited amount of resources within the network. In addition to time-independent constraints regarding aspects like scalability, resilience, and control plane communication delays, dynamically changing network conditions like traffic patterns or bandwidth demands need to be considered as well. Consequently, such dynamic environments call for a regular and fast recalculation of placements in order to adapt to the current situation in a timely manner. While an exhaustive evaluation of all possible solutions can be performed within a practically feasible time frame for small and medium-sized networks, such an approach is out of scope for large problem instances which have significantly higher time and memory requirements. Therefore, this work investigates a specialized heuristic, which takes into account a particular set of optimization objectives and returns solutions representing the possible trade-offs between them. Due to its low computation time and acceptable margin of error, this heuristic can be employed by automatic decision systems operating in dynamic environments.}, address = {Ghent, Belgium}, author = {Lange, Stanislav and Gebert, Steffen and Spoerhase, Joachim and Rygielski, Piotr and Zinner, Thomas and Kounev, Samuel and Tran-Gia, Phuoc}, booktitle = {International Teletraffic Congress (ITC 27)}, keywords = {poco}, month = 9, title = {Specialized Heuristics for the Controller Placement Problem in Large Scale SDN Networks}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-519 %A Lange, Stanislav %A Gebert, Steffen %A Spoerhase, Joachim %A Rygielski, Piotr %A Zinner, Thomas %A Kounev, Samuel %A Tran-Gia, Phuoc %B International Teletraffic Congress (ITC 27) %C Ghent, Belgium %D 2015 %T Specialized Heuristics for the Controller Placement Problem in Large Scale SDN Networks %X The Software Defined Networking~(SDN) concept introduces a paradigm shift in the networking world towards an externalized control plane which is logically centralized. When designing an SDN-based WAN architecture, it is of vital importance to find a feasible solution to the controller placement problem, i.e., to decide where to position a limited amount of resources within the network. In addition to time-independent constraints regarding aspects like scalability, resilience, and control plane communication delays, dynamically changing network conditions like traffic patterns or bandwidth demands need to be considered as well. Consequently, such dynamic environments call for a regular and fast recalculation of placements in order to adapt to the current situation in a timely manner. While an exhaustive evaluation of all possible solutions can be performed within a practically feasible time frame for small and medium-sized networks, such an approach is out of scope for large problem instances which have significantly higher time and memory requirements. Therefore, this work investigates a specialized heuristic, which takes into account a particular set of optimization objectives and returns solutions representing the possible trade-offs between them. Due to its low computation time and acceptable margin of error, this heuristic can be employed by automatic decision systems operating in dynamic environments.
• TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches Gebert, Steffen; Jarschel, Michael; Herrnleben, Stefan; Zinner, Thomas; Tran-Gia, Phuoc in 4th European Workshop on Software Defined Networks (EWSDN) (2015).
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  This demonstration introduces TableVisor, which acts as a proxy layer between an OpenFlow controller and switches. Multiple hardware switches connect to TableVisor before it establishes a connection with the OpenFlow controller instance. During connection establishment, TableVisor advertises in the answer to the controller's features-request that this switch comprises a certain number of tables, which actually reflects the number of connected switches. All communication between controller and switch is passed through the proxy layer. Depending on the type of message, it will be answered directly by TableVisor (hello, features-reply), modified in such a way that particular fields are rewritten (packet-in, flow-mod), or a response merging data from multiple switches will be returned (flow-stats). The demonstration shows TableVisor in a MPLS use case using multiple switches, which is motivated by a mobile network scenario.

  @inproceedings{info3-inproceedings-2015-527, abstract = {This demonstration introduces TableVisor, which acts as a proxy layer between an OpenFlow controller and switches. Multiple hardware switches connect to TableVisor before it establishes a connection with the OpenFlow controller instance. During connection establishment, TableVisor advertises in the answer to the controller's features-request that this switch comprises a certain number of tables, which actually reflects the number of connected switches. All communication between controller and switch is passed through the proxy layer. Depending on the type of message, it will be answered directly by TableVisor (hello, features-reply), modified in such a way that particular fields are rewritten (packet-in, flow-mod), or a response merging data from multiple switches will be returned (flow-stats). The demonstration shows TableVisor in a MPLS use case using multiple switches, which is motivated by a mobile network scenario.}, address = {Bilbao, Spain}, author = {Gebert, Steffen and Jarschel, Michael and Herrnleben, Stefan and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {4th European Workshop on Software Defined Networks (EWSDN)}, keywords = {sys:hidden:inproceedings}, month = 9, title = {TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-527 %A Gebert, Steffen %A Jarschel, Michael %A Herrnleben, Stefan %A Zinner, Thomas %A Tran-Gia, Phuoc %B 4th European Workshop on Software Defined Networks (EWSDN) %C Bilbao, Spain %D 2015 %T TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches %X This demonstration introduces TableVisor, which acts as a proxy layer between an OpenFlow controller and switches. Multiple hardware switches connect to TableVisor before it establishes a connection with the OpenFlow controller instance. During connection establishment, TableVisor advertises in the answer to the controller's features-request that this switch comprises a certain number of tables, which actually reflects the number of connected switches. All communication between controller and switch is passed through the proxy layer. Depending on the type of message, it will be answered directly by TableVisor (hello, features-reply), modified in such a way that particular fields are rewritten (packet-in, flow-mod), or a response merging data from multiple switches will be returned (flow-stats). The demonstration shows TableVisor in a MPLS use case using multiple switches, which is motivated by a mobile network scenario.
• Performance Benchmarking of a Software-Based LTE SGW Lange, Stanislav; Nguyen-Ngoc, Anh; Gebert, Steffen; Zinner, Thomas; Jarschel, Michael; Koepsel, Andreas; Sune, Marc; Raumer, Daniel; Gallenmüller, Sebastian; Carle, Georg; Tran-Gia, Phuoc in 2nd International Workshop on Management of SDN and NFV Systems (2015).
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  • [ BibTeX ]
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  Network Functions Virtualization (NFV) is a concept that aims at providing network operators with benefits in terms of cost, flexibility, and vendor independence by utilizing virtualization techniques to run network functions as software on commercial off-the-shelf (COTS) hardware. In contrast, prior solutions rely on specialized hardware for each function. Performance evaluation of such systems usually requires a dedicated testbed for each individual component. Rather than analyzing these proprietary black-box components, Virtualized Network Functions (VNFs) are pieces of software that run on COTS hardware and whose properties can be investigated in a generic testbed. However, depending on the underlying hardware, operating system, and implementation, VNFs might behave differently. Therefore, mechanisms for the performance evaluation of VNFs should be similar to benchmarking of software, where different implementations are compared by applying them to predefined test cases and scenarios. This work presents a first step towards a benchmarking framework for VNFs. Given two different implementations of a VNF that acts as LTE Serving Gateway (SGW), influence factors and key performance indicators are identified and a comparison between the two mechanisms is drawn.

  @inproceedings{info3-inproceedings-2015-533, abstract = {Network Functions Virtualization (NFV) is a concept that aims at providing network operators with benefits in terms of cost, flexibility, and vendor independence by utilizing virtualization techniques to run network functions as software on commercial off-the-shelf (COTS) hardware. In contrast, prior solutions rely on specialized hardware for each function. Performance evaluation of such systems usually requires a dedicated testbed for each individual component. Rather than analyzing these proprietary black-box components, Virtualized Network Functions (VNFs) are pieces of software that run on COTS hardware and whose properties can be investigated in a generic testbed. However, depending on the underlying hardware, operating system, and implementation, VNFs might behave differently. Therefore, mechanisms for the performance evaluation of VNFs should be similar to benchmarking of software, where different implementations are compared by applying them to predefined test cases and scenarios. This work presents a first step towards a benchmarking framework for VNFs. Given two different implementations of a VNF that acts as LTE Serving Gateway (SGW), influence factors and key performance indicators are identified and a comparison between the two mechanisms is drawn.}, address = {Barcelona, Spain}, author = {Lange, Stanislav and Nguyen-Ngoc, Anh and Gebert, Steffen and Zinner, Thomas and Jarschel, Michael and Koepsel, Andreas and Sune, Marc and Raumer, Daniel and Gallenmüller, Sebastian and Carle, Georg and Tran-Gia, Phuoc}, booktitle = {2nd International Workshop on Management of SDN and NFV Systems}, keywords = {sys:hidden:inproceedings}, month = 11, title = {Performance Benchmarking of a Software-Based LTE SGW}, year = 2015 }

  %0 Conference Paper %1 info3-inproceedings-2015-533 %A Lange, Stanislav %A Nguyen-Ngoc, Anh %A Gebert, Steffen %A Zinner, Thomas %A Jarschel, Michael %A Koepsel, Andreas %A Sune, Marc %A Raumer, Daniel %A Gallenmüller, Sebastian %A Carle, Georg %A Tran-Gia, Phuoc %B 2nd International Workshop on Management of SDN and NFV Systems %C Barcelona, Spain %D 2015 %T Performance Benchmarking of a Software-Based LTE SGW %X Network Functions Virtualization (NFV) is a concept that aims at providing network operators with benefits in terms of cost, flexibility, and vendor independence by utilizing virtualization techniques to run network functions as software on commercial off-the-shelf (COTS) hardware. In contrast, prior solutions rely on specialized hardware for each function. Performance evaluation of such systems usually requires a dedicated testbed for each individual component. Rather than analyzing these proprietary black-box components, Virtualized Network Functions (VNFs) are pieces of software that run on COTS hardware and whose properties can be investigated in a generic testbed. However, depending on the underlying hardware, operating system, and implementation, VNFs might behave differently. Therefore, mechanisms for the performance evaluation of VNFs should be similar to benchmarking of software, where different implementations are compared by applying them to predefined test cases and scenarios. This work presents a first step towards a benchmarking framework for VNFs. Given two different implementations of a VNF that acts as LTE Serving Gateway (SGW), influence factors and key performance indicators are identified and a comparison between the two mechanisms is drawn.
• Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events Gebert, Steffen; Jarschel, Michael; Hoffmann, Marco (2015, April).
  • [ BibTeX ]
  • [ EndNote ]
  @misc{info3-software-2015-22, address = {Vienna, Austria}, author = {Gebert, Steffen and Jarschel, Michael and Hoffmann, Marco}, booktitle = {Computer Communication Networks}, keywords = {sys:hidden:software}, month = 4, title = {Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events}, year = 2015 }

  %0 Generic %1 info3-software-2015-22 %A Gebert, Steffen %A Jarschel, Michael %A Hoffmann, Marco %B Computer Communication Networks %C Vienna, Austria %D 2015 %T Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events
• Continuously Delivering Your Network Gebert, Steffen; Schwartz, Christian; Zinner, Thomas; Tran-Gia, Phuoc (2015, May).
  • [ BibTeX ]
  • [ EndNote ]
  @misc{info3-poster-2015-37, address = {Ottawa, Canada}, author = {Gebert, Steffen and Schwartz, Christian and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {IEEE/IFIP International Symposium on Integrated Network Management (IM)}, keywords = {sys:hidden:poster}, month = 5, title = {Continuously Delivering Your Network}, year = 2015 }

  %0 Generic %1 info3-poster-2015-37 %A Gebert, Steffen %A Schwartz, Christian %A Zinner, Thomas %A Tran-Gia, Phuoc %B IEEE/IFIP International Symposium on Integrated Network Management (IM) %C Ottawa, Canada %D 2015 %T Continuously Delivering Your Network
• Performance Issues in SDN and NFV Tran-Gia, Phuoc; Zinner, Thomas; Gebert, Steffen (2015, May 7).
  • [ BibTeX ]
  • [ EndNote ]
  @presentation{info3-talk-2015-492, address = {University of Toronto}, author = {Tran-Gia, Phuoc and Zinner, Thomas and Gebert, Steffen}, keywords = {sys:hidden:presentation}, month = 5, title = {Performance Issues in SDN and NFV}, year = 2015 }

  %0 Generic %1 info3-talk-2015-492 %A Tran-Gia, Phuoc %A Zinner, Thomas %A Gebert, Steffen %C University of Toronto %D 2015 %T Performance Issues in SDN and NFV
• TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches Gebert, Steffen (2015, October 1).
  • [ BibTeX ]
  • [ EndNote ]
  @presentation{info3-talk-2015-496, address = {Lightning Talk at 4th European Workshop on Software Defined Networks (EWSDN), Bilbao, Spain}, author = {Gebert, Steffen}, keywords = {sys:hidden:presentation}, month = 10, title = {TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches}, year = 2015 }

  %0 Generic %1 info3-talk-2015-496 %A Gebert, Steffen %C Lightning Talk at 4th European Workshop on Software Defined Networks (EWSDN), Bilbao, Spain %D 2015 %T TableVisor: An Emulation Layer for Multi-Table OpenFlow Switches
• Heuristic Approaches to the Controller Placement Problem in Large Scale SDN Networks Lange, Stanislav; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc; Hock, David; Jarschel, Michael; Hoffmann, Marco in IEEE Transactions on Network and Service Management - Special Issue on Efficient Management of SDN and NFV-based Systems (2015). 12(1) 4–17.
  • [ Abstract ]
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  Software Defined Networking (SDN) marks a paradigm shift towards an externalized and logically centralized network control plane. A particularly important task in SDN architectures is that of controller placement, i.e., the positioning of a limited number of resources within a network in order to meet various requirements. These requirements range from latency constraints to failure tolerance and load balancing. In most scenarios, at least some of these objectives are competing, thus no single best placement is available and decision makers need to find a balanced trade-off. This work presents POCO, a framework for Pareto-based Optimal COntroller placement that provides operators with Pareto optimal placements with respect to different performance metrics. In its default configuration, POCO performs an exhaustive evaluation of all possible placements. While this is practically feasible for small and medium sized networks, realistic time and resource constraints call for an alternative in the context of large scale networks or dynamic networks whose properties change over time. For these scenarios, the POCO toolset is extended by a heuristic approach that is less accurate, but yields faster computation times. An evaluation of this heuristic is performed on a collection of real world network topologies from the Internet Topology Zoo. Utilizing a measure for quantifying the error introduced by the heuristic approach allows an analysis of the resulting trade-off between time and accuracy. Additionally, the proposed methods can be extended to solve similar virtual functions placement problems which appear in the context of Network Functions Virtualization (NFV).

  @article{info3-article-2015-131, abstract = {Software Defined Networking (SDN) marks a paradigm shift towards an externalized and logically centralized network control plane. A particularly important task in SDN architectures is that of controller placement, i.e., the positioning of a limited number of resources within a network in order to meet various requirements. These requirements range from latency constraints to failure tolerance and load balancing. In most scenarios, at least some of these objectives are competing, thus no single best placement is available and decision makers need to find a balanced trade-off. This work presents POCO, a framework for Pareto-based Optimal COntroller placement that provides operators with Pareto optimal placements with respect to different performance metrics. In its default configuration, POCO performs an exhaustive evaluation of all possible placements. While this is practically feasible for small and medium sized networks, realistic time and resource constraints call for an alternative in the context of large scale networks or dynamic networks whose properties change over time. For these scenarios, the POCO toolset is extended by a heuristic approach that is less accurate, but yields faster computation times. An evaluation of this heuristic is performed on a collection of real world network topologies from the Internet Topology Zoo. Utilizing a measure for quantifying the error introduced by the heuristic approach allows an analysis of the resulting trade-off between time and accuracy. Additionally, the proposed methods can be extended to solve similar virtual functions placement problems which appear in the context of Network Functions Virtualization (NFV).}, author = {Lange, Stanislav and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc and Hock, David and Jarschel, Michael and Hoffmann, Marco}, journal = {IEEE Transactions on Network and Service Management - Special Issue on Efficient Management of SDN and NFV-based Systems}, keywords = {poco}, number = 1, pages = {4 - 17}, title = {Heuristic Approaches to the Controller Placement Problem in Large Scale SDN Networks}, volume = 12, year = 2015 }

  %0 Journal Article %1 info3-article-2015-131 %A Lange, Stanislav %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %A Hock, David %A Jarschel, Michael %A Hoffmann, Marco %D 2015 %J IEEE Transactions on Network and Service Management - Special Issue on Efficient Management of SDN and NFV-based Systems %N 1 %P 4 - 17 %T Heuristic Approaches to the Controller Placement Problem in Large Scale SDN Networks %V 12 %X Software Defined Networking (SDN) marks a paradigm shift towards an externalized and logically centralized network control plane. A particularly important task in SDN architectures is that of controller placement, i.e., the positioning of a limited number of resources within a network in order to meet various requirements. These requirements range from latency constraints to failure tolerance and load balancing. In most scenarios, at least some of these objectives are competing, thus no single best placement is available and decision makers need to find a balanced trade-off. This work presents POCO, a framework for Pareto-based Optimal COntroller placement that provides operators with Pareto optimal placements with respect to different performance metrics. In its default configuration, POCO performs an exhaustive evaluation of all possible placements. While this is practically feasible for small and medium sized networks, realistic time and resource constraints call for an alternative in the context of large scale networks or dynamic networks whose properties change over time. For these scenarios, the POCO toolset is extended by a heuristic approach that is less accurate, but yields faster computation times. An evaluation of this heuristic is performed on a collection of real world network topologies from the Internet Topology Zoo. Utilizing a measure for quantifying the error introduced by the heuristic approach allows an analysis of the resulting trade-off between time and accuracy. Additionally, the proposed methods can be extended to solve similar virtual functions placement problems which appear in the context of Network Functions Virtualization (NFV).

• DevOps und Continuous Delivery Gebert, Steffen (2014, July 15).
  • [ BibTeX ]
  • [ EndNote ]
  @presentation{info3-talk-2014-480, address = {Datev Trendscout, Nürnberg}, author = {Gebert, Steffen}, keywords = {sys:hidden:presentation}, month = 7, title = {DevOps und Continuous Delivery}, year = 2014 }

  %0 Generic %1 info3-talk-2014-480 %A Gebert, Steffen %C Datev Trendscout, Nürnberg %D 2014 %T DevOps und Continuous Delivery
• SDN interfaces and performance analysis of SDN components Gebert, Steffen (2014, September 25).
  • [ BibTeX ]
  • [ EndNote ]
  @presentation{info3-talk-2014-482, author = {Gebert, Steffen}, keywords = {sys:hidden:presentation}, month = 9, title = {SDN interfaces and performance analysis of SDN components}, year = 2014 }

  %0 Generic %1 info3-talk-2014-482 %A Gebert, Steffen %D 2014 %T SDN interfaces and performance analysis of SDN components
• POCO-PLC: Enabling Dynamic Pareto-Optimal Resilient Controller Placement in SDN Networks Hock, David; Hartmann, Matthias; Gebert, Steffen; Zinner, Thomas; Tran-Gia, Phuoc (2014, April).
  • [ BibTeX ]
  • [ EndNote ]
  @misc{info3-software-2014-19, address = {Toronto, Canada}, author = {Hock, David and Hartmann, Matthias and Gebert, Steffen and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {Computer Communications Workshops (INFOCOM WKSHPS)}, keywords = {poco}, month = 4, title = {POCO-PLC: Enabling Dynamic Pareto-Optimal Resilient Controller Placement in SDN Networks}, year = 2014 }

  %0 Generic %1 info3-software-2014-19 %A Hock, David %A Hartmann, Matthias %A Gebert, Steffen %A Zinner, Thomas %A Tran-Gia, Phuoc %B Computer Communications Workshops (INFOCOM WKSHPS) %C Toronto, Canada %D 2014 %T POCO-PLC: Enabling Dynamic Pareto-Optimal Resilient Controller Placement in SDN Networks
• Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events Gebert, Steffen; Hock, David; Zinner, Thomas; Tran-Gia, Phuoc; Hoffmann, Marco; Jarschel, Michael; Schmidt, Ernst-Dieter; Braun, Ralf-Peter; Banse, Christian; Koepsel, Andreas (2014, August).
  • [ BibTeX ]
  • [ EndNote ]
  @misc{info3-software-2014-21, author = {Gebert, Steffen and Hock, David and Zinner, Thomas and Tran-Gia, Phuoc and Hoffmann, Marco and Jarschel, Michael and Schmidt, Ernst-Dieter and Braun, Ralf-Peter and Banse, Christian and Koepsel, Andreas}, booktitle = {SIGCOMM}, keywords = {sys:hidden:software}, month = 8, title = {Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events}, year = 2014 }

  %0 Generic %1 info3-software-2014-21 %A Gebert, Steffen %A Hock, David %A Zinner, Thomas %A Tran-Gia, Phuoc %A Hoffmann, Marco %A Jarschel, Michael %A Schmidt, Ernst-Dieter %A Braun, Ralf-Peter %A Banse, Christian %A Koepsel, Andreas %B SIGCOMM %D 2014 %T Demonstrating the Optimal Placement of Virtualized Cellular Network Functions in Case of Large Crowd Events
• POCO: A Framework for the Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks Hock, David; Gebert, Steffen; Hartmann, Matthias; Zinner, Thomas; Tran-Gia, Phuoc (2014, May).
  • [ BibTeX ]
  • [ EndNote ]
  @misc{info3-software-2014-18, address = {Krakow, Poland}, author = {Hock, David and Gebert, Steffen and Hartmann, Matthias and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {IEEE NOMS}, keywords = {poco}, month = 5, title = {POCO: A Framework for the Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks}, year = 2014 }

  %0 Generic %1 info3-software-2014-18 %A Hock, David %A Gebert, Steffen %A Hartmann, Matthias %A Zinner, Thomas %A Tran-Gia, Phuoc %B IEEE NOMS %C Krakow, Poland %D 2014 %T POCO: A Framework for the Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks
• OFCProbe: A Platform-Independent Tool for OpenFlow Controller Analysis Jarschel, Michael; Metter, Christopher; Zinner, Thomas; Gebert, Steffen; Tran-Gia, Phuoc in 5th IEEE International Conference on Communications and Electronics (IEEE ICCE 2014) (2014).
  • [ Abstract ]
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  Controller performance and behavior are key to the operation of an SDN network. Therefore, choosing the right controller implementation and corresponding set of applications is essential. In order to facilitate this decision we previously introduced a tool for controller performance analysis called ”OFCBenchmark”. In this paper, we present ”OFCProbe” a platform-independent and extended re-design of our original approach. We describe the new architecture and explain the implemented features. Finally, we provide some sample results to illustrate the kind of investigations that can be performed using the tool.

  @inproceedings{info3-inproceedings-2014-496, abstract = {Controller performance and behavior are key to the operation of an SDN network. Therefore, choosing the right controller implementation and corresponding set of applications is essential. In order to facilitate this decision we previously introduced a tool for controller performance analysis called ”OFCBenchmark”. In this paper, we present ”OFCProbe” a platform-independent and extended re-design of our original approach. We describe the new architecture and explain the implemented features. Finally, we provide some sample results to illustrate the kind of investigations that can be performed using the tool.}, address = {Da Nang, Vietnam}, author = {Jarschel, Michael and Metter, Christopher and Zinner, Thomas and Gebert, Steffen and Tran-Gia, Phuoc}, booktitle = {5th IEEE International Conference on Communications and Electronics (IEEE ICCE 2014)}, keywords = {saser-siegfried}, month = 8, title = {OFCProbe: A Platform-Independent Tool for OpenFlow Controller Analysis}, year = 2014 }

  %0 Conference Paper %1 info3-inproceedings-2014-496 %A Jarschel, Michael %A Metter, Christopher %A Zinner, Thomas %A Gebert, Steffen %A Tran-Gia, Phuoc %B 5th IEEE International Conference on Communications and Electronics (IEEE ICCE 2014) %C Da Nang, Vietnam %D 2014 %T OFCProbe: A Platform-Independent Tool for OpenFlow Controller Analysis %X Controller performance and behavior are key to the operation of an SDN network. Therefore, choosing the right controller implementation and corresponding set of applications is essential. In order to facilitate this decision we previously introduced a tool for controller performance analysis called ”OFCBenchmark”. In this paper, we present ”OFCProbe” a platform-independent and extended re-design of our original approach. We describe the new architecture and explain the implemented features. Finally, we provide some sample results to illustrate the kind of investigations that can be performed using the tool.
• Including Energy Efficiency Aspects in Multi-Layer Optical Network Design Gebert, Steffen; Hock, David; Hartmann, Matthias; Spoerhase, Joachim; Zinner, Thomas; Tran-Gia, Phuoc in 5th International Conference on Communications and Electronics (ICCE 2014) (2014).
  • [ Abstract ]
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  This paper investigates the influence of the network planning process on a higher energy-awareness of optical multi-layer core networks. In particular, we propose to remove redundant links in the network, and to route corresponding network traffic on other links. Based on the reduced network topology, we compute the required network equipment for realistic traffic demands using a network planning tool. Due to the lack of an accurate model for operational expenditures and energy consumption, we choose the link length as cost function. We show the applicability of our idea and demonstrate the energy saving potential using realistic network topologies.

  @inproceedings{info3-inproceedings-2014-492, abstract = {This paper investigates the influence of the network planning process on a higher energy-awareness of optical multi-layer core networks. In particular, we propose to remove redundant links in the network, and to route corresponding network traffic on other links. Based on the reduced network topology, we compute the required network equipment for realistic traffic demands using a network planning tool. Due to the lack of an accurate model for operational expenditures and energy consumption, we choose the link length as cost function. We show the applicability of our idea and demonstrate the energy saving potential using realistic network topologies.}, address = {Da Nang, Vietnam}, author = {Gebert, Steffen and Hock, David and Hartmann, Matthias and Spoerhase, Joachim and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {5th International Conference on Communications and Electronics (ICCE 2014)}, keywords = {saser-siegfried}, month = 7, title = {Including Energy Efficiency Aspects in Multi-Layer Optical Network Design}, year = 2014 }

  %0 Conference Paper %1 info3-inproceedings-2014-492 %A Gebert, Steffen %A Hock, David %A Hartmann, Matthias %A Spoerhase, Joachim %A Zinner, Thomas %A Tran-Gia, Phuoc %B 5th International Conference on Communications and Electronics (ICCE 2014) %C Da Nang, Vietnam %D 2014 %T Including Energy Efficiency Aspects in Multi-Layer Optical Network Design %X This paper investigates the influence of the network planning process on a higher energy-awareness of optical multi-layer core networks. In particular, we propose to remove redundant links in the network, and to route corresponding network traffic on other links. Based on the reduced network topology, we compute the required network equipment for realistic traffic demands using a network planning tool. Due to the lack of an accurate model for operational expenditures and energy consumption, we choose the link length as cost function. We show the applicability of our idea and demonstrate the energy saving potential using realistic network topologies.

• Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks Hock, David; Hartmann, Matthias; Gebert, Steffen; Jarschel, Michael; Zinner, Thomas; Tran-Gia, Phuoc in 25th International Teletraffic Congress (ITC) (2013).
  • [ Abstract ]
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  With the introduction of Software Defined Networking (SDN), the concept of an external and optionally centralized network control plane, i.e. controller, is drawing the attention of researchers and industry. A particularly important task in the SDN context is the placement of such external resources in the network. In this paper, we discuss important aspects of the controller placement problem with a focus on SDN-based core networks, including different types of resilience and failure tolerance. When several performance and resilience metrics are considered, there is usually no single best controller placement solution, but a trade-off between these metrics. We introduce our framework for resilient Pareto-based Optimal COntroller-placement (POCO) that provides the operator of a network with all Pareto-optimal placements. The ideas and mechanisms are illustrated using the Internet2 OS3E topology and further evaluated on more than 140 topologies of the Topology Zoo. In particular, our findings reveal that for most of the topologies more than 20% of all nodes need to be controllers to assure a continuous connection of all nodes to one of the controllers in any arbitrary double link or node failure scenario.

  @inproceedings{info3-inproceedings-2013-466, abstract = {With the introduction of Software Defined Networking (SDN), the concept of an external and optionally centralized network control plane, i.e. controller, is drawing the attention of researchers and industry. A particularly important task in the SDN context is the placement of such external resources in the network. In this paper, we discuss important aspects of the controller placement problem with a focus on SDN-based core networks, including different types of resilience and failure tolerance. When several performance and resilience metrics are considered, there is usually no single best controller placement solution, but a trade-off between these metrics. We introduce our framework for resilient Pareto-based Optimal COntroller-placement (POCO) that provides the operator of a network with all Pareto-optimal placements. The ideas and mechanisms are illustrated using the Internet2 OS3E topology and further evaluated on more than 140 topologies of the Topology Zoo. In particular, our findings reveal that for most of the topologies more than 20% of all nodes need to be controllers to assure a continuous connection of all nodes to one of the controllers in any arbitrary double link or node failure scenario.}, address = {Shanghai, China}, author = {Hock, David and Hartmann, Matthias and Gebert, Steffen and Jarschel, Michael and Zinner, Thomas and Tran-Gia, Phuoc}, booktitle = {25th International Teletraffic Congress (ITC)}, keywords = {poco}, month = 9, title = {Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks}, year = 2013 }

  %0 Conference Paper %1 info3-inproceedings-2013-466 %A Hock, David %A Hartmann, Matthias %A Gebert, Steffen %A Jarschel, Michael %A Zinner, Thomas %A Tran-Gia, Phuoc %B 25th International Teletraffic Congress (ITC) %C Shanghai, China %D 2013 %T Pareto-Optimal Resilient Controller Placement in SDN-based Core Networks %X With the introduction of Software Defined Networking (SDN), the concept of an external and optionally centralized network control plane, i.e. controller, is drawing the attention of researchers and industry. A particularly important task in the SDN context is the placement of such external resources in the network. In this paper, we discuss important aspects of the controller placement problem with a focus on SDN-based core networks, including different types of resilience and failure tolerance. When several performance and resilience metrics are considered, there is usually no single best controller placement solution, but a trade-off between these metrics. We introduce our framework for resilient Pareto-based Optimal COntroller-placement (POCO) that provides the operator of a network with all Pareto-optimal placements. The ideas and mechanisms are illustrated using the Internet2 OS3E topology and further evaluated on more than 140 topologies of the Topology Zoo. In particular, our findings reveal that for most of the topologies more than 20% of all nodes need to be controllers to assure a continuous connection of all nodes to one of the controllers in any arbitrary double link or node failure scenario.

• Signaling Load and Tunnel Management in a 3G Core Network Metzger, Florian; Gebert, Steffen; Salzlechner, Katharina; Rafetseder, Albert; Romirer, Peter; Tutschku, Kurt (2012).
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  @techreport{info3-techreport-2012-259, author = {Metzger, Florian and Gebert, Steffen and Salzlechner, Katharina and Rafetseder, Albert and Romirer, Peter and Tutschku, Kurt}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 9, number = 484, title = {Signaling Load and Tunnel Management in a 3G Core Network}, year = 2012 }

  %0 Report %1 info3-techreport-2012-259 %A Metzger, Florian %A Gebert, Steffen %A Salzlechner, Katharina %A Rafetseder, Albert %A Romirer, Peter %A Tutschku, Kurt %D 2012 %N 484 %T Signaling Load and Tunnel Management in a 3G Core Network
• Internet Access Traffic Measurement and Analysis Gebert, Steffen; Pries, Rastin; Schlosser, Daniel; Heck, Klaus in Traffic Monitoring and Analysis (TMA) workshop co-located with the 13th Passive and Active Measurement (PAM) conference (2012).
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  The fast changing application types and their behavior require consecutive measurements of access networks. In this paper, we present the results of a 14-day measurement in an access network connecting 600 users with the Internet. Our application classification reveals a trend back to HTTP traffic, underlines the immense usage of flash videos, and unveils a participant of a Botnet. In addition, flow and user statistics are presented, which resulting traffic models can be used for simulation and emulation of access networks.

  @inproceedings{info3-inproceedings-2012-432, abstract = {The fast changing application types and their behavior require consecutive measurements of access networks. In this paper, we present the results of a 14-day measurement in an access network connecting 600 users with the Internet. Our application classification reveals a trend back to HTTP traffic, underlines the immense usage of flash videos, and unveils a participant of a Botnet. In addition, flow and user statistics are presented, which resulting traffic models can be used for simulation and emulation of access networks.}, address = {Vienna, Austria}, author = {Gebert, Steffen and Pries, Rastin and Schlosser, Daniel and Heck, Klaus}, booktitle = {Traffic Monitoring and Analysis (TMA) workshop co-located with the 13th Passive and Active Measurement (PAM) conference}, keywords = {sys:hidden:inproceedings}, month = 3, title = {Internet Access Traffic Measurement and Analysis}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-432 %A Gebert, Steffen %A Pries, Rastin %A Schlosser, Daniel %A Heck, Klaus %B Traffic Monitoring and Analysis (TMA) workshop co-located with the 13th Passive and Active Measurement (PAM) conference %C Vienna, Austria %D 2012 %T Internet Access Traffic Measurement and Analysis %X The fast changing application types and their behavior require consecutive measurements of access networks. In this paper, we present the results of a 14-day measurement in an access network connecting 600 users with the Internet. Our application classification reveals a trend back to HTTP traffic, underlines the immense usage of flash videos, and unveils a participant of a Botnet. In addition, flow and user statistics are presented, which resulting traffic models can be used for simulation and emulation of access networks.