Dr. rer. nat. Frank Lehrieder

• Crowdsourced Network Measurements: Benefits and Best Practices Hirth, Matthias; Hoßfeld, Tobias; Mellia, Marco; Schwartz, Christian; Lehrieder, Frank in Computer Networks Special Issue on Crowdsourcing (2015).
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  Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.

  @article{info3-article-2015-135, abstract = {Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.}, author = {Hirth, Matthias and Hoßfeld, Tobias and Mellia, Marco and Schwartz, Christian and Lehrieder, Frank}, journal = {Computer Networks Special Issue on Crowdsourcing}, keywords = {sys:hidden:article}, title = {Crowdsourced Network Measurements: Benefits and Best Practices}, year = 2015 }

  %0 Journal Article %1 info3-article-2015-135 %A Hirth, Matthias %A Hoßfeld, Tobias %A Mellia, Marco %A Schwartz, Christian %A Lehrieder, Frank %D 2015 %J Computer Networks Special Issue on Crowdsourcing %T Crowdsourced Network Measurements: Benefits and Best Practices %X Network measurements are of high importance both for the operation of networks and for the design and evaluation of new management mechanisms. Therefore, several approaches exist for running network measurements, ranging from analyzing live traffic traces from campus or Internet Service Provider (ISP) networks to performing active measurements on distributed testbeds, e.g., PlanetLab, or involving volunteers. However, each method falls short, offering only a partial view of the network. For instance, the scope of passive traffic traces is limited to an ISP’s network and customers’ habits, whereas active measurements might be biased by the population or node location involved. To complement these techniques, we pro- pose to use (commercial) crowdsourcing platforms for network measurements. They permit a controllable, diverse and realistic view of the Internet and pro- vide better control than do measurements with voluntary participants. In this study, we compare crowdsourcing with traditional measurement techniques, describe possible pitfalls and limitations, and present best practices to overcome these issues. The contribution of this paper is a guideline for researchers to understand when and how to exploit crowdsourcing for network measurements.
• Wikipedia and its Network of Human and Automated Authors from a Social Network Perspective Hirth, Matthias; Lehrieder, Frank; Oberste-Vorth, Stephan; Hoßfeld, Tobias; Tran-Gia, Phuoc (2015).
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  @techreport{info3-techreport-2015-268, author = {Hirth, Matthias and Lehrieder, Frank and Oberste-Vorth, Stephan and Hoßfeld, Tobias and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 4, number = 494, title = {Wikipedia and its Network of Human and Automated Authors from a Social Network Perspective}, year = 2015 }

  %0 Report %1 info3-techreport-2015-268 %A Hirth, Matthias %A Lehrieder, Frank %A Oberste-Vorth, Stephan %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %D 2015 %N 494 %T Wikipedia and its Network of Human and Automated Authors from a Social Network Perspective

• Performance Analysis of the Trade-off Between Signalling Load and Power Consumption for Popular Smartphone Apps in 3G Networks Schwartz, Christian; Hoßfeld, Tobias; Lehrieder, Frank; Tran-Gia, Phuoc (2013).
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  @techreport{info3-techreport-2013-260, author = {Schwartz, Christian and Hoßfeld, Tobias and Lehrieder, Frank and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 1, number = 485, title = {Performance Analysis of the Trade-off Between Signalling Load and Power Consumption for Popular Smartphone Apps in 3G Networks}, year = 2013 }

  %0 Report %1 info3-techreport-2013-260 %A Schwartz, Christian %A Hoßfeld, Tobias %A Lehrieder, Frank %A Tran-Gia, Phuoc %D 2013 %N 485 %T Performance Analysis of the Trade-off Between Signalling Load and Power Consumption for Popular Smartphone Apps in 3G Networks
• RCFT: A Termination Method for Simple PCN-Based Flow Control Lehrieder, Frank; Menth, Michael in Journal of Network and Systems Management (2013).
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  Pre-congestion notification (PCN) conveys information about load conditions in Differentiated Services IP networks to boundary nodes. This information is currently used for admission control and flow termination. Flow termination complements admission control, e.g., in case of failures when admitted traffic is rerouted and causes overload on backup paths. Existing approaches for PCN-based admission control and flow termination operate on ingress-egress aggregates and rely on a signalling protocol that regularly reports measured PCN feedback from all egress nodes to all ingress nodes. However, this signalling protocol is neither defined nor available, and the methods have also other intrinsic shortcomings that result from their operations on ingress-egress aggregates. While there is already a PCN-based admission control method that works without additional signalling of measured PCN feedback, a solid flow termination method with that property is still missing. In this paper we present the novel regular-check-based flow termination method (RCFT). It does not rely on measured PCN feedback, fills the identified gap, and allows for a PCN architecture without signalling of measured feedback. We explain RCFT in detail and investigate its termination behavior under various conditions. Moreover, we study the use of PCN-based flow control for on/off traffic. These results are of general nature and apply to any system using PCN-based flow termination.

  @article{info3-article-2013-107, abstract = {Pre-congestion notification (PCN) conveys information about load conditions in Differentiated Services IP networks to boundary nodes. This information is currently used for admission control and flow termination. Flow termination complements admission control, e.g., in case of failures when admitted traffic is rerouted and causes overload on backup paths. Existing approaches for PCN-based admission control and flow termination operate on ingress-egress aggregates and rely on a signalling protocol that regularly reports measured PCN feedback from all egress nodes to all ingress nodes. However, this signalling protocol is neither defined nor available, and the methods have also other intrinsic shortcomings that result from their operations on ingress-egress aggregates. While there is already a PCN-based admission control method that works without additional signalling of measured PCN feedback, a solid flow termination method with that property is still missing. In this paper we present the novel regular-check-based flow termination method (RCFT). It does not rely on measured PCN feedback, fills the identified gap, and allows for a PCN architecture without signalling of measured feedback. We explain RCFT in detail and investigate its termination behavior under various conditions. Moreover, we study the use of PCN-based flow control for on/off traffic. These results are of general nature and apply to any system using PCN-based flow termination.}, author = {Lehrieder, Frank and Menth, Michael}, journal = {Journal of Network and Systems Management}, keywords = {sys:hidden:article}, title = {RCFT: A Termination Method for Simple PCN-Based Flow Control}, year = 2013 }

  %0 Journal Article %1 info3-article-2013-107 %A Lehrieder, Frank %A Menth, Michael %D 2013 %J Journal of Network and Systems Management %T RCFT: A Termination Method for Simple PCN-Based Flow Control %X Pre-congestion notification (PCN) conveys information about load conditions in Differentiated Services IP networks to boundary nodes. This information is currently used for admission control and flow termination. Flow termination complements admission control, e.g., in case of failures when admitted traffic is rerouted and causes overload on backup paths. Existing approaches for PCN-based admission control and flow termination operate on ingress-egress aggregates and rely on a signalling protocol that regularly reports measured PCN feedback from all egress nodes to all ingress nodes. However, this signalling protocol is neither defined nor available, and the methods have also other intrinsic shortcomings that result from their operations on ingress-egress aggregates. While there is already a PCN-based admission control method that works without additional signalling of measured PCN feedback, a solid flow termination method with that property is still missing. In this paper we present the novel regular-check-based flow termination method (RCFT). It does not rely on measured PCN feedback, fills the identified gap, and allows for a PCN architecture without signalling of measured feedback. We explain RCFT in detail and investigate its termination behavior under various conditions. Moreover, we study the use of PCN-based flow control for on/off traffic. These results are of general nature and apply to any system using PCN-based flow termination.
• Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE Schwartz, Christian; Hoßfeld, Tobias; Lehrieder, Frank; Tran-Gia, Phuoc in Journal of Computer Networks and Communications (2013). 1–22.
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  The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.

  @article{info3-article-2013-108, abstract = {The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.}, author = {Schwartz, Christian and Hoßfeld, Tobias and Lehrieder, Frank and Tran-Gia, Phuoc}, journal = {Journal of Computer Networks and Communications}, keywords = {sys:hidden:article}, month = 9, pages = {1 - 22}, title = {Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE}, year = 2013 }

  %0 Journal Article %1 info3-article-2013-108 %A Schwartz, Christian %A Hoßfeld, Tobias %A Lehrieder, Frank %A Tran-Gia, Phuoc %D 2013 %J Journal of Computer Networks and Communications %P 1 - 22 %T Angry Apps: The Impact of Network Timer Selection on Power Consumption, Signalling Load, and Web QoE %X The popularity of smartphones and mobile applications has experienced a considerable growth during recent years and this growth is expected to continue in the future. Since smartphones have only very limited energy resources, battery efficiency is one of the deter- mining factors for a good user experience. Therefore, some smartphones tear down connec- tions to the mobile network soon after a completed data transmission to reduce the power consumption of their transmission unit. However, frequent connection re-establishments caused by apps which send or receive small amounts of data often lead to a heavy signalling load within the mobile network. One of the major contributions of this article is the investigation of the resulting trade-off between energy consumption at the smartphone and the generated signalling traffic in the mobile network. We explain that this trade-off can be controlled by the connection release timeout and study the impact of this parameter for a number of popular apps that cover a wide range of traffic characteristics in terms of bandwidth requirements and resulting signalling traffic. Finally, we study the impact of the timer settings on QoE for web traffic. This is an important aspect since connection establishments do not only lead to signalling traffic, but they also increase the load time of web pages.
• Performance Evaluation and Optimization of Content Distribution using Overlay Networks Lehrieder, Frank (2013, February).
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  @phdthesis{info3-dissertation-2013-33, author = {Lehrieder, Frank}, keywords = {sys:hidden:dissertation}, month = 2, title = {Performance Evaluation and Optimization of Content Distribution using Overlay Networks}, year = 2013 }

  %0 Thesis %1 info3-dissertation-2013-33 %A Lehrieder, Frank %D 2013 %T Performance Evaluation and Optimization of Content Distribution using Overlay Networks
• Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns Schwartz, Christian; Lehrieder, Frank; Wamser, Florian; Hoßfeld, Tobias; Tran-Gia, Phuoc in Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT (2013).
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  The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.

  @inproceedings{info3-inproceedings-2013-481, abstract = {The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.}, address = {Genova, Italy}, author = {Schwartz, Christian and Lehrieder, Frank and Wamser, Florian and Hoßfeld, Tobias and Tran-Gia, Phuoc}, booktitle = {Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT}, keywords = {oekonet}, month = 9, title = {Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns}, year = 2013 }

  %0 Conference Paper %1 info3-inproceedings-2013-481 %A Schwartz, Christian %A Lehrieder, Frank %A Wamser, Florian %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %B Tyrrhenian International Workshop 2013 on Digital Communications: Green ICT %C Genova, Italy %D 2013 %T Smart-Phone Energy Consumption Vs. 3G Signaling Load: The Influence of Application Traffic Patterns %X The high signaling load in today’s UMTS networks has recently lead to severe problems and network outages of several hours, so called Signaling Storms. The reason is that cer- tain network access patterns of popular smart-phone applications trigger frequent connection re-establishments, which are signaled to the network via the radio resource control (RRC) protocol. As a consequence of the network agnostic implementation of smart- phone applications, entities of the mobile network operator may experience overload, while energy consumption at the smart- phones is mutually determined. The aim of this work is to study the impact of traffic charac- teristics on the power consumption of the smart-phone and the signaling messages in the mobile network. For that purpose, we first develop a simple model for the RRC states of a smart-phone. Second, we estimate the resulting power drain and the signalling traffic of the smart-phone. Then, we investigate the applicability of our model by comparing analytical with simulation results for real-world smart-phone traffic measurements. Finally, we evaluate the effect of network parameter optimization on traffic with different statistical characteristics. Our counter-intuitive results show that in particular bursty traffic patterns are suitable for UMTS networks while periodic patterns may cause increased power consumption and signaling overload – in contrast to classical queueing systems.

• Cache Capacity Allocation for BitTorrent-like Systems to Minimize Inter-ISP Traffic Pacifici, Valentino; Lehrieder, Frank; Dán, György in IEEE Infocom (2012).
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  Many Internet service providers (ISPs) have deployed peer-to-peer (P2P) caches in their networks in order to decrease costly inter-ISP traffic. A P2P cache stores parts of the most popular contents locally, and if possible serves the requests of local peers to decrease the transit traffic. Traditionally, P2P cache resource management focuses on managing the storage resource of the cache such as to maximize the transit traffic savings. In this paper we show that when there are many overlays competing for the upload bandwidth of a P2P cache then in order to maximize the transit traffic savings the cache’s upload bandwidth should be actively allocated among the overlays. We formulate the problem of P2P cache capacity allocation as a Markov decision process, and describe two approximations to the optimal cache capacity allocation policy. Based on the insights obtained from the approximate policies we propose a cache capacity allocation policy for BitTorrent-like P2P networks. We use extensive simulations to evaluate the performance of the proposed policies, and show that cache capacity allocation can improve the transit traffic savings by up to 30 to 60 percent. We validate the results via BitTorrent experiments on Planet-lab.

  @inproceedings{info3-inproceedings-2012-431, abstract = {Many Internet service providers (ISPs) have deployed peer-to-peer (P2P) caches in their networks in order to decrease costly inter-ISP traffic. A P2P cache stores parts of the most popular contents locally, and if possible serves the requests of local peers to decrease the transit traffic. Traditionally, P2P cache resource management focuses on managing the storage resource of the cache such as to maximize the transit traffic savings. In this paper we show that when there are many overlays competing for the upload bandwidth of a P2P cache then in order to maximize the transit traffic savings the cache’s upload bandwidth should be actively allocated among the overlays. We formulate the problem of P2P cache capacity allocation as a Markov decision process, and describe two approximations to the optimal cache capacity allocation policy. Based on the insights obtained from the approximate policies we propose a cache capacity allocation policy for BitTorrent-like P2P networks. We use extensive simulations to evaluate the performance of the proposed policies, and show that cache capacity allocation can improve the transit traffic savings by up to 30 to 60 percent. We validate the results via BitTorrent experiments on Planet-lab.}, address = {Orlando, USA}, author = {Pacifici, Valentino and Lehrieder, Frank and Dán, György}, booktitle = {IEEE Infocom}, keywords = {sys:hidden:inproceedings}, month = 3, title = {Cache Capacity Allocation for BitTorrent-like Systems to Minimize Inter-ISP Traffic}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-431 %A Pacifici, Valentino %A Lehrieder, Frank %A Dán, György %B IEEE Infocom %C Orlando, USA %D 2012 %T Cache Capacity Allocation for BitTorrent-like Systems to Minimize Inter-ISP Traffic %X Many Internet service providers (ISPs) have deployed peer-to-peer (P2P) caches in their networks in order to decrease costly inter-ISP traffic. A P2P cache stores parts of the most popular contents locally, and if possible serves the requests of local peers to decrease the transit traffic. Traditionally, P2P cache resource management focuses on managing the storage resource of the cache such as to maximize the transit traffic savings. In this paper we show that when there are many overlays competing for the upload bandwidth of a P2P cache then in order to maximize the transit traffic savings the cache’s upload bandwidth should be actively allocated among the overlays. We formulate the problem of P2P cache capacity allocation as a Markov decision process, and describe two approximations to the optimal cache capacity allocation policy. Based on the insights obtained from the approximate policies we propose a cache capacity allocation policy for BitTorrent-like P2P networks. We use extensive simulations to evaluate the performance of the proposed policies, and show that cache capacity allocation can improve the transit traffic savings by up to 30 to 60 percent. We validate the results via BitTorrent experiments on Planet-lab.
• Wikipedia and its Network of Authors from a Social Network Perspective Hirth, Matthias; Lehrieder, Frank; Oberste-Vorth, Stephan; Hoßfeld, Tobias; Tran-Gia, Phuoc in International Conference on Communications and Electronics (ICCE) (2012).
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  Online social networks (OSNs) become more and more important in today's social and business life. Therefore, considerable effort is put in research to gain a deeper knowledge of the development of these networks and their dynamics. However, most of the existing literature is based on very limited subsets of the network data, which is often filtered by the OSN operator providing the data or biased by the crawling mechanisms used to obtain the data. This makes it difficult to analyze the temporal evolution of OSNs based on complete data. To overcome this issue, we investigate the dynamics of the publicly available collaboration network of the Wikipedia authors as an example for an OSN-like network. In particular, we study the temporal evolution of this network since its beginning and demonstrate that it exhibits prominent similarities to well known social networks such as the small-world phenomenon. This indicates that the insights gained from the analysis of Wikipedia's collaboration network might be transferable to social networks in general.

  @inproceedings{info3-inproceedings-2012-450, abstract = {Online social networks (OSNs) become more and more important in today's social and business life. Therefore, considerable effort is put in research to gain a deeper knowledge of the development of these networks and their dynamics. However, most of the existing literature is based on very limited subsets of the network data, which is often filtered by the OSN operator providing the data or biased by the crawling mechanisms used to obtain the data. This makes it difficult to analyze the temporal evolution of OSNs based on complete data. To overcome this issue, we investigate the dynamics of the publicly available collaboration network of the Wikipedia authors as an example for an OSN-like network. In particular, we study the temporal evolution of this network since its beginning and demonstrate that it exhibits prominent similarities to well known social networks such as the small-world phenomenon. This indicates that the insights gained from the analysis of Wikipedia's collaboration network might be transferable to social networks in general.}, address = {Hue, Vietnam}, author = {Hirth, Matthias and Lehrieder, Frank and Oberste-Vorth, Stephan and Hoßfeld, Tobias and Tran-Gia, Phuoc}, booktitle = {International Conference on Communications and Electronics (ICCE)}, keywords = {sys:hidden:inproceedings}, month = 8, title = {Wikipedia and its Network of Authors from a Social Network Perspective}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-450 %A Hirth, Matthias %A Lehrieder, Frank %A Oberste-Vorth, Stephan %A Hoßfeld, Tobias %A Tran-Gia, Phuoc %B International Conference on Communications and Electronics (ICCE) %C Hue, Vietnam %D 2012 %T Wikipedia and its Network of Authors from a Social Network Perspective %X Online social networks (OSNs) become more and more important in today's social and business life. Therefore, considerable effort is put in research to gain a deeper knowledge of the development of these networks and their dynamics. However, most of the existing literature is based on very limited subsets of the network data, which is often filtered by the OSN operator providing the data or biased by the crawling mechanisms used to obtain the data. This makes it difficult to analyze the temporal evolution of OSNs based on complete data. To overcome this issue, we investigate the dynamics of the publicly available collaboration network of the Wikipedia authors as an example for an OSN-like network. In particular, we study the temporal evolution of this network since its beginning and demonstrate that it exhibits prominent similarities to well known social networks such as the small-world phenomenon. This indicates that the insights gained from the analysis of Wikipedia's collaboration network might be transferable to social networks in general.
• Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms Burger, Valentin; Lehrieder, Frank; Hoßfeld, Tobias; Seedorf, Jan in International Teletraffic Congress (ITC 24) (2012).
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  BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.

  @inproceedings{info3-inproceedings-2012-451, abstract = {BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.}, address = {Krakow, Poland}, author = {Burger, Valentin and Lehrieder, Frank and Hoßfeld, Tobias and Seedorf, Jan}, booktitle = {International Teletraffic Congress (ITC 24)}, keywords = {oekonet}, month = 9, title = {Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-451 %A Burger, Valentin %A Lehrieder, Frank %A Hoßfeld, Tobias %A Seedorf, Jan %B International Teletraffic Congress (ITC 24) %C Krakow, Poland %D 2012 %T Who Profits from Peer-to-Peer File-Sharing? Traffic Optimization Potential in BitTorrent Swarms %X BitTorrent-based peer-to-peer networks constitute a significant share of Internet traffic. Therefore, the IETF working group on application layer traffic optimization (ALTO) discusses several approaches for guiding the BitTorrent traffic that aim at reducing the large amount of inter-ISP traffic costs caused by these networks. However, performance evaluations of these approaches are mostly limited to artificial scenarios that do not take into account the real Internet topology with its inter-ISP relationships and the actual distribution of BitTorrent users across autonomous systems (AS). In this study, we use measurements of the distribution of a large number of live BitTorrent networks and combine them with the AS-level Internet topology provided by Caida.org. Based on this data, we estimate in which tier of the Internet hierarchy BitTorrent traffic is mainly located and how much optimization potential exists for the different types of ISPs. Therewith, traffic flow and revenue implications of guiding Internet-wide BitTorrent swarms are analyzed. Our results show that tier-1 ISPs profit from the un-managed exchange of peer-to-peer traffic and that these profits significantly decrease when the other ISPs would apply ALTO solutions.
• A Flexible OpenFlow-Controller Benchmark Jarschel, Michael; Lehrieder, Frank; Magyari, Zsolt; Pries, Rastin in 1st European Workshop on Software Defined Networks (EWSDN 2012) (2012).
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  Software defined networking (SDN) promises a way to more flexible networks that can adapt to changing demands. At the same time these networks should also benefit from simpler management mechanisms. This is achieved by moving the network control out of the forwarding devices to purpose-tailored software-applications on top of a ”networking operating system”. Currently, the most notable representative of this approach is OpenFlow. In the OpenFlow architecture the operating system is represented by the OpenFlow controller. As the key component of the OpenFlow ecosystem, the behavior and performance of the controller are significant for the entire network. Therefore, it is important to understand these influence factors, when planning an OpenFlow-based SDN deployment. In this work, we introduce a tool to help achieving just that - a flexible OpenFlow controller benchmark. The benchmark creates a set of message-generating virtual switches, which can be configured independently from each other to emulate a certain scenario and also keep their own statistics. This way a granular controller performance analysis is possible.

  @inproceedings{info3-inproceedings-2012-455, abstract = {Software defined networking (SDN) promises a way to more flexible networks that can adapt to changing demands. At the same time these networks should also benefit from simpler management mechanisms. This is achieved by moving the network control out of the forwarding devices to purpose-tailored software-applications on top of a ”networking operating system”. Currently, the most notable representative of this approach is OpenFlow. In the OpenFlow architecture the operating system is represented by the OpenFlow controller. As the key component of the OpenFlow ecosystem, the behavior and performance of the controller are significant for the entire network. Therefore, it is important to understand these influence factors, when planning an OpenFlow-based SDN deployment. In this work, we introduce a tool to help achieving just that - a flexible OpenFlow controller benchmark. The benchmark creates a set of message-generating virtual switches, which can be configured independently from each other to emulate a certain scenario and also keep their own statistics. This way a granular controller performance analysis is possible.}, address = {Darmstadt, Germany}, author = {Jarschel, Michael and Lehrieder, Frank and Magyari, Zsolt and Pries, Rastin}, booktitle = {1st European Workshop on Software Defined Networks (EWSDN 2012)}, keywords = {openflow}, month = 10, title = {A Flexible OpenFlow-Controller Benchmark}, year = 2012 }

  %0 Conference Paper %1 info3-inproceedings-2012-455 %A Jarschel, Michael %A Lehrieder, Frank %A Magyari, Zsolt %A Pries, Rastin %B 1st European Workshop on Software Defined Networks (EWSDN 2012) %C Darmstadt, Germany %D 2012 %T A Flexible OpenFlow-Controller Benchmark %X Software defined networking (SDN) promises a way to more flexible networks that can adapt to changing demands. At the same time these networks should also benefit from simpler management mechanisms. This is achieved by moving the network control out of the forwarding devices to purpose-tailored software-applications on top of a ”networking operating system”. Currently, the most notable representative of this approach is OpenFlow. In the OpenFlow architecture the operating system is represented by the OpenFlow controller. As the key component of the OpenFlow ecosystem, the behavior and performance of the controller are significant for the entire network. Therefore, it is important to understand these influence factors, when planning an OpenFlow-based SDN deployment. In this work, we introduce a tool to help achieving just that - a flexible OpenFlow controller benchmark. The benchmark creates a set of message-generating virtual switches, which can be configured independently from each other to emulate a certain scenario and also keep their own statistics. This way a granular controller performance analysis is possible.
• Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications Lehrieder, Frank; Dán, György; Hoßfeld, Tobias; Oechsner, Simon; Singeorzan, Vlad in IEEE/ACM Transactions on Networking (2012). 20(4)
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  Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.

  @article{info3-article-2012-94, abstract = {Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.}, author = {Lehrieder, Frank and Dán, György and Hoßfeld, Tobias and Oechsner, Simon and Singeorzan, Vlad}, journal = {IEEE/ACM Transactions on Networking}, keywords = {sys:hidden:article}, title = {Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications}, volume = {20(4)}, year = 2012 }

  %0 Journal Article %1 info3-article-2012-94 %A Lehrieder, Frank %A Dán, György %A Hoßfeld, Tobias %A Oechsner, Simon %A Singeorzan, Vlad %D 2012 %J IEEE/ACM Transactions on Networking %T Caching for BitTorrent-like P2P Systems: A Simple Fluid Model and its Implications %V 20(4) %X Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer-related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches—caches already available on the market and caches expected to become available in the future—can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Motivated by our findings, we propose a proximity-aware peer-selection mechanism that avoids the increase of the transit traffic and improves the cache efficiency.We support the analytical results by extensive simulations and experiments with real BitTorrent clients.
• Cooperative Traffic Management for Video Streaming Overlays Pussep, Konstantin; Lehrieder, Frank; Gross, Christian; Oechsner, Simon; Guenther, Markus; Meyer, Sebastian in Computer Networks (2012). 56(3) 1118–1130.
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  Peer-to-Peer (P2P) based overlays often ignore the boundaries of network domains and make traffic management challenging for network operators. Locality-aware techniques are a promising approach to alleviate this impact, but often benefit only network operators and fail to provide similar benefits to end-users and overlay providers. This is especially severe with video streaming overlays that are responsible for large amount of Internet traffic. In this paper we present and evaluate a collaborative approach where a network operator measures the behavior of overlay users and promotes a subset of them in terms of up- and download bandwidth. This creates an incentive to users and overlay providers to cooperate by using locality awareness according to the operator's policies. We evaluate our approach both with a real application and via extensive simulations to analyze the user selection metrics and the impact on different network operators. Our study shows that this cooperative traffic management approach leads to a situation that is beneficial for users, content providers, and network operators.

  @article{info3-article-2012-92, abstract = {Peer-to-Peer (P2P) based overlays often ignore the boundaries of network domains and make traffic management challenging for network operators. Locality-aware techniques are a promising approach to alleviate this impact, but often benefit only network operators and fail to provide similar benefits to end-users and overlay providers. This is especially severe with video streaming overlays that are responsible for large amount of Internet traffic. In this paper we present and evaluate a collaborative approach where a network operator measures the behavior of overlay users and promotes a subset of them in terms of up- and download bandwidth. This creates an incentive to users and overlay providers to cooperate by using locality awareness according to the operator's policies. We evaluate our approach both with a real application and via extensive simulations to analyze the user selection metrics and the impact on different network operators. Our study shows that this cooperative traffic management approach leads to a situation that is beneficial for users, content providers, and network operators.}, author = {Pussep, Konstantin and Lehrieder, Frank and Gross, Christian and Oechsner, Simon and Guenther, Markus and Meyer, Sebastian}, journal = {Computer Networks}, keywords = {sys:hidden:article}, pages = {1118–1130}, title = {Cooperative Traffic Management for Video Streaming Overlays}, volume = {56(3)}, year = 2012 }

  %0 Journal Article %1 info3-article-2012-92 %A Pussep, Konstantin %A Lehrieder, Frank %A Gross, Christian %A Oechsner, Simon %A Guenther, Markus %A Meyer, Sebastian %D 2012 %J Computer Networks %P 1118–1130 %T Cooperative Traffic Management for Video Streaming Overlays %V 56(3) %X Peer-to-Peer (P2P) based overlays often ignore the boundaries of network domains and make traffic management challenging for network operators. Locality-aware techniques are a promising approach to alleviate this impact, but often benefit only network operators and fail to provide similar benefits to end-users and overlay providers. This is especially severe with video streaming overlays that are responsible for large amount of Internet traffic. In this paper we present and evaluate a collaborative approach where a network operator measures the behavior of overlay users and promotes a subset of them in terms of up- and download bandwidth. This creates an incentive to users and overlay providers to cooperate by using locality awareness according to the operator's policies. We evaluate our approach both with a real application and via extensive simulations to analyze the user selection metrics and the impact on different network operators. Our study shows that this cooperative traffic management approach leads to a situation that is beneficial for users, content providers, and network operators.
• Performance of PCN-Based Admission Control under Challenging Conditions Menth, Michael; Lehrieder, Frank in IEEE/ACM Transactions on Networking (2012). 20(2) 422–435.
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  Pre-congestion notification (PCN) is a packet marking technique for IP networks to notify egress nodes of a socalled PCN domain whether the traffic rate on some links exceeds certain configurable bounds. This feedback is used by decision points for admission control (AC) to block new flows when the traffic load is already high. PCN-based AC is simpler than other AC methods because interior routers do not need to keep perflow states. Therefore, it is currently being standardized by the IETF. We discuss various realization options and analyze their performance in the presence of flash crowds or with multipath routing by means of simulation and mathematical modeling. Such situations can be aggravated by insufficient flow aggregation, long round-trip times, on/off traffic, delayed media, inappropriate marker configuration, and smoothed feedback.

  @article{info3-article-2012-91, abstract = {Pre-congestion notification (PCN) is a packet marking technique for IP networks to notify egress nodes of a socalled PCN domain whether the traffic rate on some links exceeds certain configurable bounds. This feedback is used by decision points for admission control (AC) to block new flows when the traffic load is already high. PCN-based AC is simpler than other AC methods because interior routers do not need to keep perflow states. Therefore, it is currently being standardized by the IETF. We discuss various realization options and analyze their performance in the presence of flash crowds or with multipath routing by means of simulation and mathematical modeling. Such situations can be aggravated by insufficient flow aggregation, long round-trip times, on/off traffic, delayed media, inappropriate marker configuration, and smoothed feedback.}, author = {Menth, Michael and Lehrieder, Frank}, journal = {IEEE/ACM Transactions on Networking}, keywords = {sys:hidden:article}, month = 4, pages = {422-435}, title = {Performance of PCN-Based Admission Control under Challenging Conditions}, volume = {20(2)}, year = 2012 }

  %0 Journal Article %1 info3-article-2012-91 %A Menth, Michael %A Lehrieder, Frank %D 2012 %J IEEE/ACM Transactions on Networking %P 422-435 %T Performance of PCN-Based Admission Control under Challenging Conditions %V 20(2) %X Pre-congestion notification (PCN) is a packet marking technique for IP networks to notify egress nodes of a socalled PCN domain whether the traffic rate on some links exceeds certain configurable bounds. This feedback is used by decision points for admission control (AC) to block new flows when the traffic load is already high. PCN-based AC is simpler than other AC methods because interior routers do not need to keep perflow states. Therefore, it is currently being standardized by the IETF. We discuss various realization options and analyze their performance in the presence of flash crowds or with multipath routing by means of simulation and mathematical modeling. Such situations can be aggravated by insufficient flow aggregation, long round-trip times, on/off traffic, delayed media, inappropriate marker configuration, and smoothed feedback.
• A Flexible OpenFlow-Controller Benchmark Jarschel, Michael; Lehrieder, Frank; Magyari, Zsolt; Pries, Rastin (2012, October 26).
  • [ BibTeX ]
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  @presentation{info3-talk-2012-450, address = {European Workshop on Software Defined Networks, Darmstadt, Germany}, author = {Jarschel, Michael and Lehrieder, Frank and Magyari, Zsolt and Pries, Rastin}, keywords = {openflow}, month = 10, title = {A Flexible OpenFlow-Controller Benchmark}, year = 2012 }

  %0 Generic %1 info3-talk-2012-450 %A Jarschel, Michael %A Lehrieder, Frank %A Magyari, Zsolt %A Pries, Rastin %C European Workshop on Software Defined Networks, Darmstadt, Germany %D 2012 %T A Flexible OpenFlow-Controller Benchmark

• PCN-Based Marked Flow Termination Menth, Michael; Lehrieder, Frank in Computer Communications (2011). 34 2082–2093.
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  Pre-congestion notification (PCN) uses packet metering and marking to notify boundary nodes of a Differentiated Services IP network if configured rate thresholds have been exceeded on some links. This feedback is used for PCN-based admission control and flow termination. While admission control is rather well understood, flow termination is a new flow control function and useful especially in case of failures or during flash crowds. We present marked flow termination as a new class of termination algorithms which terminate overload traffic gradually and that work well with multipath routing. We study their termination behavior, give recommendation for their configuration, and discuss their benefits and shortcomings.

  @article{info3-article-2011-90, abstract = {Pre-congestion notification (PCN) uses packet metering and marking to notify boundary nodes of a Differentiated Services IP network if configured rate thresholds have been exceeded on some links. This feedback is used for PCN-based admission control and flow termination. While admission control is rather well understood, flow termination is a new flow control function and useful especially in case of failures or during flash crowds. We present marked flow termination as a new class of termination algorithms which terminate overload traffic gradually and that work well with multipath routing. We study their termination behavior, give recommendation for their configuration, and discuss their benefits and shortcomings.}, author = {Menth, Michael and Lehrieder, Frank}, journal = {Computer Communications}, keywords = {sys:hidden:article}, month = 11, pages = {2082-2093}, title = {PCN-Based Marked Flow Termination}, volume = 34, year = 2011 }

  %0 Journal Article %1 info3-article-2011-90 %A Menth, Michael %A Lehrieder, Frank %D 2011 %J Computer Communications %P 2082-2093 %T PCN-Based Marked Flow Termination %V 34 %X Pre-congestion notification (PCN) uses packet metering and marking to notify boundary nodes of a Differentiated Services IP network if configured rate thresholds have been exceeded on some links. This feedback is used for PCN-based admission control and flow termination. While admission control is rather well understood, flow termination is a new flow control function and useful especially in case of failures or during flash crowds. We present marked flow termination as a new class of termination algorithms which terminate overload traffic gradually and that work well with multipath routing. We study their termination behavior, give recommendation for their configuration, and discuss their benefits and shortcomings.
• Characterization of BitTorrent Swarms and their Distribution in the Internet Hoßfeld, Tobias; Lehrieder, Frank; Hock, David; Oechsner, Simon; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian in Computer Networks (2011). 55(5) 1197–1215.
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  The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.

  @article{info3-article-2011-83, abstract = {The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.}, author = {Hoßfeld, Tobias and Lehrieder, Frank and Hock, David and Oechsner, Simon and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 4, pages = {1197-1215}, title = {Characterization of BitTorrent Swarms and their Distribution in the Internet}, volume = {55(5)}, year = 2011 }

  %0 Journal Article %1 info3-article-2011-83 %A Hoßfeld, Tobias %A Lehrieder, Frank %A Hock, David %A Oechsner, Simon %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %D 2011 %J Computer Networks %P 1197-1215 %T Characterization of BitTorrent Swarms and their Distribution in the Internet %V 55(5) %X The optimization of overlay traffic resulting from applications such as BitTorrent is a challenge addressed by several recent research initiatives. However, the assessment of such optimization techniques and their performance in the real Internet remains difficult. Despite a considerable set of works measuring real-life BitTorrent swarms, several characteristics of those swarms relevant for the optimization of overlay traffic have not yet been investigated. In this work, we address this lack of realistic swarm statistics by presenting our measurement results. In particular, we provide a statistical characterization of the swarm sizes, the distribution of peers over autonomous systems (ASs), the fraction of peers in the largest AS, and the size of the shared files. To this end, we consider different types of shared content and identify particular characteristics of regional swarms. The selection of the presented data is inspired by ongoing discussions in the IETF working group on application layer traffic optimization (ALTO). Our study is intended to provide input for the design and the assessment of ALTO solutions for BitTorrent, but the applicability of the results is not limited to that purpose.
• Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks Lehrieder, Frank; Oechsner, Simon; Hoßfeld, Tobias; Staehle, Dirk; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian in International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management (2011). 21(1)
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  Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.

  @article{info3-article-2011-82, abstract = {Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.}, author = {Lehrieder, Frank and Oechsner, Simon and Hoßfeld, Tobias and Staehle, Dirk and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, journal = {International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management}, keywords = {sys:hidden:article}, month = 1, title = {Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks}, volume = {21(1)}, year = 2011 }

  %0 Journal Article %1 info3-article-2011-82 %A Lehrieder, Frank %A Oechsner, Simon %A Hoßfeld, Tobias %A Staehle, Dirk %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %D 2011 %J International Journal of Network Management (IJNM), Special Issue on Economic Traffic Management %T Mitigating Unfairness in Locality-Aware Peer-to-Peer Networks %V 21(1) %X Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and to simultaneously increase the performance from the viewpoint of the P2P users, i.e., to shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used mostly assume homogeneous peer distributions. This is not the case in practice according to recent measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer heavily depends on the used locality-aware peer selection and the specific scenario. This contradicts the principle of economic traffic management (ETM) which aims for a solution where all involved players benefit and consequently have an incentive to adopt locality-awareness. Therefore, we propose and evaluate refinements of current proposals, achieving that all users of P2P networks can be sure that their application performance is not reduced. This mitigates the unfairness introduced by current proposals which is a key requirement for a broad acceptance of the concept of locality-awareness in the user community of P2P networks.
• On the Benefits of P2P Cache Capacity Allocation Lehrieder, Frank; Pacifici, Valentino; Dán, György (2011, September).
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  @misc{info3-poster-2011-28, author = {Lehrieder, Frank and Pacifici, Valentino and Dán, György}, booktitle = {23rd International Teletraffic Congress (ITC 2011)}, keywords = {sys:hidden:poster}, month = 9, title = {On the Benefits of P2P Cache Capacity Allocation}, year = 2011 }

  %0 Generic %1 info3-poster-2011-28 %A Lehrieder, Frank %A Pacifici, Valentino %A Dán, György %B 23rd International Teletraffic Congress (ITC 2011) %D 2011 %T On the Benefits of P2P Cache Capacity Allocation
• Influence of traffic management solutions on Quality of Experience for prevailing overlay applications Stankiewicz, Rafal; Cholda, Piotr; Domzal, Jerzy; Wojcik, Robert; Hoßfeld, Tobias; Zinner, Thomas; Oechsner, Simon; Lehrieder, Frank in Proceedings of the 7th Conference on Next Generation Internet Networks (NGI) (2011).
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  Different sorts of peer-to-peer (P2P) applications emerge every day and they are becoming more and more popular. The performance of such applications may be measured by means of Quality of Experience (QoE) metrics. In this paper, we survey the factors that influence these metrics. Moreover, we assess the impact of traffic management solutions (e.g. proposed by ALTO or SmoothIT) on perceived QoE for the dominant overlay applications. The possible regulatory issues regarding QoE for P2P applications are also mentioned.

  @inproceedings{info3-inproceedings-2011-414, abstract = {Different sorts of peer-to-peer (P2P) applications emerge every day and they are becoming more and more popular. The performance of such applications may be measured by means of Quality of Experience (QoE) metrics. In this paper, we survey the factors that influence these metrics. Moreover, we assess the impact of traffic management solutions (e.g. proposed by ALTO or SmoothIT) on perceived QoE for the dominant overlay applications. The possible regulatory issues regarding QoE for P2P applications are also mentioned.}, address = {Kaiserslautern, Germany}, author = {Stankiewicz, Rafal and Cholda, Piotr and Domzal, Jerzy and Wojcik, Robert and Hoßfeld, Tobias and Zinner, Thomas and Oechsner, Simon and Lehrieder, Frank}, booktitle = {Proceedings of the 7th Conference on Next Generation Internet Networks (NGI)}, keywords = {sys:hidden:inproceedings}, month = 6, title = {Influence of traffic management solutions on Quality of Experience for prevailing overlay applications}, year = 2011 }

  %0 Conference Paper %1 info3-inproceedings-2011-414 %A Stankiewicz, Rafal %A Cholda, Piotr %A Domzal, Jerzy %A Wojcik, Robert %A Hoßfeld, Tobias %A Zinner, Thomas %A Oechsner, Simon %A Lehrieder, Frank %B Proceedings of the 7th Conference on Next Generation Internet Networks (NGI) %C Kaiserslautern, Germany %D 2011 %T Influence of traffic management solutions on Quality of Experience for prevailing overlay applications %X Different sorts of peer-to-peer (P2P) applications emerge every day and they are becoming more and more popular. The performance of such applications may be measured by means of Quality of Experience (QoE) metrics. In this paper, we survey the factors that influence these metrics. Moreover, we assess the impact of traffic management solutions (e.g. proposed by ALTO or SmoothIT) on perceived QoE for the dominant overlay applications. The possible regulatory issues regarding QoE for P2P applications are also mentioned.
• Cache Capacity Allocation to Overlay Swarms Papafili, Ioanna; Stamoulis, George D.; Lehrieder, Frank; Kleine, Benjamin; Oechsner, Simon in International Workshop on Self-Organizing Systems (2011).
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  Peer-to-peer applications generate huge volumes of Internet traffic, thus leading to higher congestion, as well as higher costs for the ISPs particularly due to inter-domain traffic. The traditional traffic management approaches employed by ISPs (e.g. traffic shaping or even throttling) often lead to a deterioration of users‟ Quality-of-Experience. Previous works have verified that the insertion of ISP-owned Peers (IoPs) can deal effectively with this situation. The mechanism offers caching while exploiting the self-organizing structure of overlays. Thus, it leads to both improved performance for peers and reduced inter-domain traffic costs for ISPs. In this paper, we study how the available IoP bandwidth capacity should be allocated among the various swarms that it can possibly join. In particular, we identify a variety of factors that influence the effectiveness of Swarm Selection and Bandwidth Allocation, and we investigate their impact on the practically relevant example of BitTorrent, primarily by means of simulations.

  @inproceedings{info3-inproceedings-2011-402, abstract = {Peer-to-peer applications generate huge volumes of Internet traffic, thus leading to higher congestion, as well as higher costs for the ISPs particularly due to inter-domain traffic. The traditional traffic management approaches employed by ISPs (e.g. traffic shaping or even throttling) often lead to a deterioration of users‟ Quality-of-Experience. Previous works have verified that the insertion of ISP-owned Peers (IoPs) can deal effectively with this situation. The mechanism offers caching while exploiting the self-organizing structure of overlays. Thus, it leads to both improved performance for peers and reduced inter-domain traffic costs for ISPs. In this paper, we study how the available IoP bandwidth capacity should be allocated among the various swarms that it can possibly join. In particular, we identify a variety of factors that influence the effectiveness of Swarm Selection and Bandwidth Allocation, and we investigate their impact on the practically relevant example of BitTorrent, primarily by means of simulations.}, address = {Karlsruhe, Germany}, author = {Papafili, Ioanna and Stamoulis, George D. and Lehrieder, Frank and Kleine, Benjamin and Oechsner, Simon}, booktitle = {International Workshop on Self-Organizing Systems}, keywords = {sys:hidden:inproceedings}, month = 2, title = {Cache Capacity Allocation to Overlay Swarms}, year = 2011 }

  %0 Conference Paper %1 info3-inproceedings-2011-402 %A Papafili, Ioanna %A Stamoulis, George D. %A Lehrieder, Frank %A Kleine, Benjamin %A Oechsner, Simon %B International Workshop on Self-Organizing Systems %C Karlsruhe, Germany %D 2011 %T Cache Capacity Allocation to Overlay Swarms %X Peer-to-peer applications generate huge volumes of Internet traffic, thus leading to higher congestion, as well as higher costs for the ISPs particularly due to inter-domain traffic. The traditional traffic management approaches employed by ISPs (e.g. traffic shaping or even throttling) often lead to a deterioration of users‟ Quality-of-Experience. Previous works have verified that the insertion of ISP-owned Peers (IoPs) can deal effectively with this situation. The mechanism offers caching while exploiting the self-organizing structure of overlays. Thus, it leads to both improved performance for peers and reduced inter-domain traffic costs for ISPs. In this paper, we study how the available IoP bandwidth capacity should be allocated among the various swarms that it can possibly join. In particular, we identify a variety of factors that influence the effectiveness of Swarm Selection and Bandwidth Allocation, and we investigate their impact on the practically relevant example of BitTorrent, primarily by means of simulations.
• Assessment of Economic Traffic Management of Overlay Traffic: Methodology and Results Papafili, Ioanna; Stamoulis, George D.; Stankiewicz, Rafal; Oechsner, Simon; Pussep, Konstantin; Wojcik, Robert; Domzal, Jerzy; Staehle, Dirk; Lehrieder, Frank; Stiller, Burkhard in Future Internet Assembly (FIA) Book: Future Internet Achievements and Promising Technology, J. D. et al. (ed.) (2011).
  • [ Abstract ]
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  Overlay applications generate huge amounts of traffic in the Internet, which determines a problem for Internet Service Providers, since it results in high charges for inter-domain traffic. Traditional traffic management techniques cannot deal successfully with overlay traffic. An incentive-based approach that employs economic concepts and mechanisms is required in order to deal with the overlay traffic in a way that is mutually beneficial for all stakeholders of the Future Internet. This TripleWin situation is the target of Economic Traffic Management (ETM). A wide variety of techniques are employed by ETM for optimizing overlay traffic management considering performance requirements of overlay and underlay networks together with cost implications for ISPs. However, the assessment of ETM requires an innovative methodology. In this article this methodology is described and major results are presented as obtained accordingly from the evaluation of different ETM mechanisms.

  @incollection{info3-incollection-2011-16, abstract = {Overlay applications generate huge amounts of traffic in the Internet, which determines a problem for Internet Service Providers, since it results in high charges for inter-domain traffic. Traditional traffic management techniques cannot deal successfully with overlay traffic. An incentive-based approach that employs economic concepts and mechanisms is required in order to deal with the overlay traffic in a way that is mutually beneficial for all stakeholders of the Future Internet. This TripleWin situation is the target of Economic Traffic Management (ETM). A wide variety of techniques are employed by ETM for optimizing overlay traffic management considering performance requirements of overlay and underlay networks together with cost implications for ISPs. However, the assessment of ETM requires an innovative methodology. In this article this methodology is described and major results are presented as obtained accordingly from the evaluation of different ETM mechanisms.}, author = {Papafili, Ioanna and Stamoulis, George D. and Stankiewicz, Rafal and Oechsner, Simon and Pussep, Konstantin and Wojcik, Robert and Domzal, Jerzy and Staehle, Dirk and Lehrieder, Frank and Stiller, Burkhard}, booktitle = {Future Internet Assembly (FIA) Book: Future Internet Achievements and Promising Technology}, editor = {et al., John Domingue}, keywords = {myown}, publisher = {Springer LNCS}, title = {Assessment of Economic Traffic Management of Overlay Traffic: Methodology and Results}, year = 2011 }

  %0 Book Section %1 info3-incollection-2011-16 %A Papafili, Ioanna %A Stamoulis, George D. %A Stankiewicz, Rafal %A Oechsner, Simon %A Pussep, Konstantin %A Wojcik, Robert %A Domzal, Jerzy %A Staehle, Dirk %A Lehrieder, Frank %A Stiller, Burkhard %B Future Internet Assembly (FIA) Book: Future Internet Achievements and Promising Technology %D 2011 %E et al., John Domingue %I Springer LNCS %T Assessment of Economic Traffic Management of Overlay Traffic: Methodology and Results %X Overlay applications generate huge amounts of traffic in the Internet, which determines a problem for Internet Service Providers, since it results in high charges for inter-domain traffic. Traditional traffic management techniques cannot deal successfully with overlay traffic. An incentive-based approach that employs economic concepts and mechanisms is required in order to deal with the overlay traffic in a way that is mutually beneficial for all stakeholders of the Future Internet. This TripleWin situation is the target of Economic Traffic Management (ETM). A wide variety of techniques are employed by ETM for optimizing overlay traffic management considering performance requirements of overlay and underlay networks together with cost implications for ISPs. However, the assessment of ETM requires an innovative methodology. In this article this methodology is described and major results are presented as obtained accordingly from the evaluation of different ETM mechanisms.

• BGP-based Locality Promotion for P2P Applications Racz, Peter; Oechsner, Simon; Lehrieder, Frank in International Conference on Computer Communication Networks (ICCCN) 2010 (2010).
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  P2P applications attract a lot of users and generate the dominant portion of the overall traffic in the Internet today. On the one hand, this large amount of traffic results in high operational costs for ISPs, mainly because of expensive interdomain connections. On the other hand, the performance of P2P applications is constricted by suboptimal peer selection or by bandwidth limitations of ISPs. To overcome these problems, the collaboration of P2P applications and ISPs is desirable, where locality promotion is one of the possible approaches. In this paper, we propose a locality promotion mechanism based on BGP routing information of an ISP and show by simulations that it can reduce inter-domain traffic, prefers shorter connections and peering links over transit links while P2P applications can achieve a better performance as well.

  @inproceedings{info3-inproceedings-2010-377, abstract = {P2P applications attract a lot of users and generate the dominant portion of the overall traffic in the Internet today. On the one hand, this large amount of traffic results in high operational costs for ISPs, mainly because of expensive interdomain connections. On the other hand, the performance of P2P applications is constricted by suboptimal peer selection or by bandwidth limitations of ISPs. To overcome these problems, the collaboration of P2P applications and ISPs is desirable, where locality promotion is one of the possible approaches. In this paper, we propose a locality promotion mechanism based on BGP routing information of an ISP and show by simulations that it can reduce inter-domain traffic, prefers shorter connections and peering links over transit links while P2P applications can achieve a better performance as well.}, address = {Zurich, Switzerland}, author = {Racz, Peter and Oechsner, Simon and Lehrieder, Frank}, booktitle = {International Conference on Computer Communication Networks (ICCCN) 2010}, keywords = {sys:hidden:inproceedings}, month = 8, title = {BGP-based Locality Promotion for P2P Applications}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-377 %A Racz, Peter %A Oechsner, Simon %A Lehrieder, Frank %B International Conference on Computer Communication Networks (ICCCN) 2010 %C Zurich, Switzerland %D 2010 %T BGP-based Locality Promotion for P2P Applications %X P2P applications attract a lot of users and generate the dominant portion of the overall traffic in the Internet today. On the one hand, this large amount of traffic results in high operational costs for ISPs, mainly because of expensive interdomain connections. On the other hand, the performance of P2P applications is constricted by suboptimal peer selection or by bandwidth limitations of ISPs. To overcome these problems, the collaboration of P2P applications and ISPs is desirable, where locality promotion is one of the possible approaches. In this paper, we propose a locality promotion mechanism based on BGP routing information of an ISP and show by simulations that it can reduce inter-domain traffic, prefers shorter connections and peering links over transit links while P2P applications can achieve a better performance as well.
• A Survey of PCN-Based Admission Control and Flow Termination Menth, Michael; Lehrieder, Frank; Briscoe, Bob; Eardley, Philip; Moncaster, Toby; Babiarz, Jozef; Charny, Anna; (Joy) Zhang, Xinyang; Taylor, Tom; Chan, Kwok-Ho; Satoh, Daisuke; Geib, Ruediger; Karagiannis, Georgios in IEEE Communications Surveys & Tutorials (2010). 12(3)
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  Pre-congestion notification (PCN) provides feedback about load conditions in a network to its boundary nodes. The PCN working group of the IETF discusses the use of PCN to implement admission control (AC) and flow termination (FT) for prioritized realtime traffic in a DiffServ domain. Admission control (AC) is a well-known flow control function that blocks admission requests of new flows when they need to be carried over a link whose admitted PCN rate already exceeds an admissible rate. Flow termination (FT) is a new flow control function that terminates some already admitted flows when they are carried over a link whose admitted PCN rate exceeds a supportable rate. The latter condition can occur in spite of AC, e.g., when traffic is rerouted due to network failures. This survey gives an introduction to PCN and is a primer for this new technology. It presents and discusses the multitude of architectural design options in an early stage of the standardization process in a comprehensive and streamlined way before only a subset of them is standardized by the IETF. It brings PCN from the IETF to the research community and serves as historical record.

  @article{info3-article-2010-76, abstract = {Pre-congestion notification (PCN) provides feedback about load conditions in a network to its boundary nodes. The PCN working group of the IETF discusses the use of PCN to implement admission control (AC) and flow termination (FT) for prioritized realtime traffic in a DiffServ domain. Admission control (AC) is a well-known flow control function that blocks admission requests of new flows when they need to be carried over a link whose admitted PCN rate already exceeds an admissible rate. Flow termination (FT) is a new flow control function that terminates some already admitted flows when they are carried over a link whose admitted PCN rate exceeds a supportable rate. The latter condition can occur in spite of AC, e.g., when traffic is rerouted due to network failures. This survey gives an introduction to PCN and is a primer for this new technology. It presents and discusses the multitude of architectural design options in an early stage of the standardization process in a comprehensive and streamlined way before only a subset of them is standardized by the IETF. It brings PCN from the IETF to the research community and serves as historical record.}, author = {Menth, Michael and Lehrieder, Frank and Briscoe, Bob and Eardley, Philip and Moncaster, Toby and Babiarz, Jozef and Charny, Anna and (Joy) Zhang, Xinyang and Taylor, Tom and Chan, Kwok-Ho and Satoh, Daisuke and Geib, Ruediger and Karagiannis, Georgios}, journal = {IEEE Communications Surveys & Tutorials}, keywords = {sys:hidden:article}, month = 7, title = {A Survey of PCN-Based Admission Control and Flow Termination}, volume = {12(3)}, year = 2010 }

  %0 Journal Article %1 info3-article-2010-76 %A Menth, Michael %A Lehrieder, Frank %A Briscoe, Bob %A Eardley, Philip %A Moncaster, Toby %A Babiarz, Jozef %A Charny, Anna %A (Joy) Zhang, Xinyang %A Taylor, Tom %A Chan, Kwok-Ho %A Satoh, Daisuke %A Geib, Ruediger %A Karagiannis, Georgios %D 2010 %J IEEE Communications Surveys & Tutorials %T A Survey of PCN-Based Admission Control and Flow Termination %V 12(3) %X Pre-congestion notification (PCN) provides feedback about load conditions in a network to its boundary nodes. The PCN working group of the IETF discusses the use of PCN to implement admission control (AC) and flow termination (FT) for prioritized realtime traffic in a DiffServ domain. Admission control (AC) is a well-known flow control function that blocks admission requests of new flows when they need to be carried over a link whose admitted PCN rate already exceeds an admissible rate. Flow termination (FT) is a new flow control function that terminates some already admitted flows when they are carried over a link whose admitted PCN rate exceeds a supportable rate. The latter condition can occur in spite of AC, e.g., when traffic is rerouted due to network failures. This survey gives an introduction to PCN and is a primer for this new technology. It presents and discusses the multitude of architectural design options in an early stage of the standardization process in a comprehensive and streamlined way before only a subset of them is standardized by the IETF. It brings PCN from the IETF to the research community and serves as historical record.
• The Impact of Caching on BitTorrent-like Peer-to-peer Systems Lehrieder, Frank; Dán, György; Hoßfeld, Tobias; Oechsner, Simon; Singeorzan, Vlad in 10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010 (2010).
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  Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches - caches already available on the market and caches expected to become available in the future - can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks, and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Our analytical results are supported by extensive simulations and experiments with real BitTorrent clients.

  @inproceedings{info3-inproceedings-2010-387, abstract = {Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches - caches already available on the market and caches expected to become available in the future - can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks, and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Our analytical results are supported by extensive simulations and experiments with real BitTorrent clients.}, address = {Best Paper Award, Delft, the Netherlands}, author = {Lehrieder, Frank and Dán, György and Hoßfeld, Tobias and Oechsner, Simon and Singeorzan, Vlad}, booktitle = {10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010}, keywords = {ispeer}, month = 8, title = {The Impact of Caching on BitTorrent-like Peer-to-peer Systems}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-387 %A Lehrieder, Frank %A Dán, György %A Hoßfeld, Tobias %A Oechsner, Simon %A Singeorzan, Vlad %B 10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010 %C Best Paper Award, Delft, the Netherlands %D 2010 %T The Impact of Caching on BitTorrent-like Peer-to-peer Systems %X Peer-to-peer file-sharing systems are responsible for a significant share of the traffic between Internet service providers (ISPs) in the Internet. In order to decrease their peer-to-peer related transit traffic costs, many ISPs have deployed caches for peer-to-peer traffic in recent years. We consider how the different types of peer-to-peer caches - caches already available on the market and caches expected to become available in the future - can possibly affect the amount of inter-ISP traffic. We develop a fluid model that captures the effects of the caches on the system dynamics of peer-to-peer networks, and show that caches can have adverse effects on the system dynamics depending on the system parameters. We combine the fluid model with a simple model of inter-ISP traffic and show that the impact of caches cannot be accurately assessed without considering the effects of the caches on the system dynamics. We identify scenarios when caching actually leads to increased transit traffic. Our analytical results are supported by extensive simulations and experiments with real BitTorrent clients.
• Overlay Connection Usage in BitTorrent Swarms Oechsner, Simon; Lehrieder, Frank; Staehle, Dirk in 3rd Workshop on Economic Traffic Management (2010).
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  The amount of peer-to-peer (P2P) traffic and its inefficient utilization of network resources make it a high priority for traffic management. Due to the distributed nature of P2P overlays, a promising approach for a management scheme is to change the client behavior and its utilization of overlay connections. However, from the viewpoint of a client, there are different categories of overlay connections. In this paper, we discern between these different types of overlay connections in BitTorrent, the currently most popular P2P file-sharing application. A simulation study of BitTorrent and a video-streaming derivate called Tribler provides insights into the usage of these types of connections for data exchange. Thus, traffic management based on client behavior can be optimized by efficiently targeting connections which carry the most traffic. We also show the implications of these results for locality-awareness mechanisms such as Biased Neighbor Selection and Biased Unchoking.

  @inproceedings{info3-inproceedings-2010-386, abstract = {The amount of peer-to-peer (P2P) traffic and its inefficient utilization of network resources make it a high priority for traffic management. Due to the distributed nature of P2P overlays, a promising approach for a management scheme is to change the client behavior and its utilization of overlay connections. However, from the viewpoint of a client, there are different categories of overlay connections. In this paper, we discern between these different types of overlay connections in BitTorrent, the currently most popular P2P file-sharing application. A simulation study of BitTorrent and a video-streaming derivate called Tribler provides insights into the usage of these types of connections for data exchange. Thus, traffic management based on client behavior can be optimized by efficiently targeting connections which carry the most traffic. We also show the implications of these results for locality-awareness mechanisms such as Biased Neighbor Selection and Biased Unchoking.}, address = {Collocated with 22nd International Teletraffic Congress (ITC 22), Amsterdam, Netherlands}, author = {Oechsner, Simon and Lehrieder, Frank and Staehle, Dirk}, booktitle = {3rd Workshop on Economic Traffic Management}, keywords = {sys:hidden:inproceedings}, month = 9, title = {Overlay Connection Usage in BitTorrent Swarms}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-386 %A Oechsner, Simon %A Lehrieder, Frank %A Staehle, Dirk %B 3rd Workshop on Economic Traffic Management %C Collocated with 22nd International Teletraffic Congress (ITC 22), Amsterdam, Netherlands %D 2010 %T Overlay Connection Usage in BitTorrent Swarms %X The amount of peer-to-peer (P2P) traffic and its inefficient utilization of network resources make it a high priority for traffic management. Due to the distributed nature of P2P overlays, a promising approach for a management scheme is to change the client behavior and its utilization of overlay connections. However, from the viewpoint of a client, there are different categories of overlay connections. In this paper, we discern between these different types of overlay connections in BitTorrent, the currently most popular P2P file-sharing application. A simulation study of BitTorrent and a video-streaming derivate called Tribler provides insights into the usage of these types of connections for data exchange. Thus, traffic management based on client behavior can be optimized by efficiently targeting connections which carry the most traffic. We also show the implications of these results for locality-awareness mechanisms such as Biased Neighbor Selection and Biased Unchoking.
• Can P2P-Users Benefit from Locality-Awareness? Lehrieder, Frank; Oechsner, Simon; Hoßfeld, Tobias; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian in 10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010 (2010).
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  Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and simultaneously increase the performance from the viewpoint of the P2P users, i.e, shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used assume mostly homogeneous peer distributions and that all peers have the same access speed. This is not the case in practice according to several measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions and heterogeneous access bandwidths of peers. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer depends heavily on the used locality-aware peer selection and the concrete scenario. Therefore, we conclude that current proposals need to be refined so that users of P2P networks can be sure that they also benefit from their use. Otherwise, a broad acceptance of the concept of locality-awareness in the user community of P2P networks will not take place.

  @inproceedings{info3-inproceedings-2010-388, abstract = {Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and simultaneously increase the performance from the viewpoint of the P2P users, i.e, shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used assume mostly homogeneous peer distributions and that all peers have the same access speed. This is not the case in practice according to several measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions and heterogeneous access bandwidths of peers. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer depends heavily on the used locality-aware peer selection and the concrete scenario. Therefore, we conclude that current proposals need to be refined so that users of P2P networks can be sure that they also benefit from their use. Otherwise, a broad acceptance of the concept of locality-awareness in the user community of P2P networks will not take place.}, address = {Delft, the Netherlands}, author = {Lehrieder, Frank and Oechsner, Simon and Hoßfeld, Tobias and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, booktitle = {10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010}, keywords = {sys:hidden:inproceedings}, month = 8, title = {Can P2P-Users Benefit from Locality-Awareness?}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-388 %A Lehrieder, Frank %A Oechsner, Simon %A Hoßfeld, Tobias %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %B 10th IEEE International Conference on Peer-to-Peer Computing 2010 - IEEE P2P 2010 %C Delft, the Netherlands %D 2010 %T Can P2P-Users Benefit from Locality-Awareness? %X Locality-awareness is considered as a promising approach to increase the efficiency of content distribution by peer-to-peer (P2P) networks, e.g., BitTorrent. It is intended to reduce the inter-domain traffic which is costly for Internet service providers (ISPs) and simultaneously increase the performance from the viewpoint of the P2P users, i.e, shorten download times. This win-win situation should be achieved by a preferred exchange of information between peers which are located closely to each other in the underlying network topology. A set of studies shows that these approaches can lead to a win-win situation under certain conditions, and to a win-no lose situation in most cases. However, the scenarios used assume mostly homogeneous peer distributions and that all peers have the same access speed. This is not the case in practice according to several measurement studies. Therefore, we extend previous work in this paper by studying scenarios with real-life, skewed peer distributions and heterogeneous access bandwidths of peers. We show that even a win-no lose situation is difficult to achieve under those conditions and that the actual impact for a specific peer depends heavily on the used locality-aware peer selection and the concrete scenario. Therefore, we conclude that current proposals need to be refined so that users of P2P networks can be sure that they also benefit from their use. Otherwise, a broad acceptance of the concept of locality-awareness in the user community of P2P networks will not take place.
• PCN-Based Marked Flow Termination Menth, Michael; Lehrieder, Frank (2010).
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  @techreport{info3-techreport-2010-249, author = {Menth, Michael and Lehrieder, Frank}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 3, number = 469, title = {PCN-Based Marked Flow Termination}, year = 2010 }

  %0 Report %1 info3-techreport-2010-249 %A Menth, Michael %A Lehrieder, Frank %D 2010 %N 469 %T PCN-Based Marked Flow Termination
• Applicability of PCN-Based Admission Control Menth, Michael; Lehrieder, Frank (2010).
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  @techreport{info3-techreport-2010-248, author = {Menth, Michael and Lehrieder, Frank}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 3, number = 468, title = {Applicability of PCN-Based Admission Control}, year = 2010 }

  %0 Report %1 info3-techreport-2010-248 %A Menth, Michael %A Lehrieder, Frank %D 2010 %N 468 %T Applicability of PCN-Based Admission Control
• Performance Evaluation of P2P Caches: Flash-Crowd Case Chołda, Piotr; Domzał, Jerzy; Wojcik, Robert; Stankiewicz, Rafał; Lehrieder, Frank; Hoßfeld, Tobias; Oechsner, Simon; Singeorzan, Vlad in Australasian Telecommunication Networks and Applications Conference (ATNAC) 2010 (2010).
  • [ Abstract ]
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  Peer-to-peer (P2P) based content distribution networks (CDNs), e.g., BitTorrent, are widely used in the today’s Internet. Since all peers interested in a specific content provide storage and upload capacity those CDNs facilitate a cheap and easy distribution of large amounts of data. However, they generate a lot of costs for Internet Service Providers (ISPs) as normal users also act as a source for downloads. One option for ISPs to encounter the problem of the costly inter-domain traffic is to establish P2P caches. In this study we investigate the potential of those caches in flash-crowd scenarios, i.e., when a large number of peers tries to download the content at the same time. To that end, we perform simulations as well as experiments with real BitTorrent clients. The evaluation shows that ISPs as well as P2P users will benefit from the use of caches.

  @inproceedings{info3-inproceedings-2010-395, abstract = {Peer-to-peer (P2P) based content distribution networks (CDNs), e.g., BitTorrent, are widely used in the today’s Internet. Since all peers interested in a specific content provide storage and upload capacity those CDNs facilitate a cheap and easy distribution of large amounts of data. However, they generate a lot of costs for Internet Service Providers (ISPs) as normal users also act as a source for downloads. One option for ISPs to encounter the problem of the costly inter-domain traffic is to establish P2P caches. In this study we investigate the potential of those caches in flash-crowd scenarios, i.e., when a large number of peers tries to download the content at the same time. To that end, we perform simulations as well as experiments with real BitTorrent clients. The evaluation shows that ISPs as well as P2P users will benefit from the use of caches.}, address = {Auckland, New Zealand}, author = {Chołda, Piotr and Domzał, Jerzy and Wojcik, Robert and Stankiewicz, Rafał and Lehrieder, Frank and Hoßfeld, Tobias and Oechsner, Simon and Singeorzan, Vlad}, booktitle = {Australasian Telecommunication Networks and Applications Conference (ATNAC) 2010}, keywords = {sys:hidden:inproceedings}, month = 11, title = {Performance Evaluation of P2P Caches: Flash-Crowd Case}, year = 2010 }

  %0 Conference Paper %1 info3-inproceedings-2010-395 %A Chołda, Piotr %A Domzał, Jerzy %A Wojcik, Robert %A Stankiewicz, Rafał %A Lehrieder, Frank %A Hoßfeld, Tobias %A Oechsner, Simon %A Singeorzan, Vlad %B Australasian Telecommunication Networks and Applications Conference (ATNAC) 2010 %C Auckland, New Zealand %D 2010 %T Performance Evaluation of P2P Caches: Flash-Crowd Case %X Peer-to-peer (P2P) based content distribution networks (CDNs), e.g., BitTorrent, are widely used in the today’s Internet. Since all peers interested in a specific content provide storage and upload capacity those CDNs facilitate a cheap and easy distribution of large amounts of data. However, they generate a lot of costs for Internet Service Providers (ISPs) as normal users also act as a source for downloads. One option for ISPs to encounter the problem of the costly inter-domain traffic is to establish P2P caches. In this study we investigate the potential of those caches in flash-crowd scenarios, i.e., when a large number of peers tries to download the content at the same time. To that end, we perform simulations as well as experiments with real BitTorrent clients. The evaluation shows that ISPs as well as P2P users will benefit from the use of caches.
• PCN-Based Measured Rate Termination Menth, Michael; Lehrieder, Frank in Computer Networks (2010). 54(13)
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  Overload in a packet-based network can be prevented by admitting or blocking new flows depending on its load conditions. However, overload can occur in spite of admission control due to unforseen events, e.g., when admitted traffic is rerouted in the network after a failure. To restore quality of service for the majority of admitted flows in such cases, flow termination has been proposed as a novel control function. We present several flow termination algorithms that measure so-called pre-congestion notification (PCN) feedback. We analyze their advantages and shortcomings in particular under challenging conditions. The results improve the understanding of PCN technology which is currently being standardized by the Internet Engineering Task Force (IETF).

  @article{info3-article-2010-75, abstract = {Overload in a packet-based network can be prevented by admitting or blocking new flows depending on its load conditions. However, overload can occur in spite of admission control due to unforseen events, e.g., when admitted traffic is rerouted in the network after a failure. To restore quality of service for the majority of admitted flows in such cases, flow termination has been proposed as a novel control function. We present several flow termination algorithms that measure so-called pre-congestion notification (PCN) feedback. We analyze their advantages and shortcomings in particular under challenging conditions. The results improve the understanding of PCN technology which is currently being standardized by the Internet Engineering Task Force (IETF).}, author = {Menth, Michael and Lehrieder, Frank}, journal = {Computer Networks}, keywords = {sys:hidden:article}, month = 9, title = {PCN-Based Measured Rate Termination}, volume = {54(13)}, year = 2010 }

  %0 Journal Article %1 info3-article-2010-75 %A Menth, Michael %A Lehrieder, Frank %D 2010 %J Computer Networks %T PCN-Based Measured Rate Termination %V 54(13) %X Overload in a packet-based network can be prevented by admitting or blocking new flows depending on its load conditions. However, overload can occur in spite of admission control due to unforseen events, e.g., when admitted traffic is rerouted in the network after a failure. To restore quality of service for the majority of admitted flows in such cases, flow termination has been proposed as a novel control function. We present several flow termination algorithms that measure so-called pre-congestion notification (PCN) feedback. We analyze their advantages and shortcomings in particular under challenging conditions. The results improve the understanding of PCN technology which is currently being standardized by the Internet Engineering Task Force (IETF).

• An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers Hoßfeld, Tobias; Hausheer, David; Hecht, Fabio; Lehrieder, Frank; Oechsner, Simon; Papafili, Ioanna; Racz, Peter; Soursos, Sergios; Staehle, Dirk; Stamoulis, George D.; Tran-Gia, Phuoc; Stiller, Burkhard in FIA Prague Book, ISBN 978-1-60750-007-0, G. Tselentis, J. Domingue, A. Galis, A. Gavras, D. Hausheer, S. Krco, V. Lotz, T. Zahariadis (eds.) (2009).
  • [ Abstract ]
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  Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.

  @incollection{info3-incollection-2009-12, abstract = {Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.}, author = {Hoßfeld, Tobias and Hausheer, David and Hecht, Fabio and Lehrieder, Frank and Oechsner, Simon and Papafili, Ioanna and Racz, Peter and Soursos, Sergios and Staehle, Dirk and Stamoulis, George D. and Tran-Gia, Phuoc and Stiller, Burkhard}, booktitle = {FIA Prague Book, ISBN 978-1-60750-007-0}, editor = {Tselentis, Georgios and Domingue, John and Galis, Alex and Gavras, Anastasius and Hausheer, David and Krco, Srdjan and Lotz, Volkmar and Zahariadis, Theodore}, keywords = {myown}, month = 5, publisher = {IOS Press Books Online}, title = {An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers}, year = 2009 }

  %0 Book Section %1 info3-incollection-2009-12 %A Hoßfeld, Tobias %A Hausheer, David %A Hecht, Fabio %A Lehrieder, Frank %A Oechsner, Simon %A Papafili, Ioanna %A Racz, Peter %A Soursos, Sergios %A Staehle, Dirk %A Stamoulis, George D. %A Tran-Gia, Phuoc %A Stiller, Burkhard %B FIA Prague Book, ISBN 978-1-60750-007-0 %D 2009 %E Tselentis, Georgios %E Domingue, John %E Galis, Alex %E Gavras, Anastasius %E Hausheer, David %E Krco, Srdjan %E Lotz, Volkmar %E Zahariadis, Theodore %I IOS Press Books Online %T An Economic Traffic Management Approach to Enable the TripleWin for Users, ISPs, and Overlay Providers %X Socio-economic aspects play an increasingly important role in the Future Internet. To enable a TripleWin situation for the involved players, i.e. the end users, the ISPs and telecommunication operators, and the service providers, a new, incentive-based concept is proposed referred to as Economic Traffic Management (ETM). It aims at reducing costs within the network while improving the Quality-of-Experience (QoE) for end users. In particular, peer-to-peer (P2P) overlay applications generate a large amount of costs due to inter-domain traffic. ETM solution approaches have to take into account (a) the traffic patterns stemming from the overlay application, (b) the charging models for transit traffic, and (c) the applicability and efficiency of the proposed solution. The complex interaction between these three components and its consequences is demonstrated on selected examples. As a result it is shown that different ETM approaches have to be combined for an overall solution. To this end, the paper derives functional and non-functional requirements for designing ETM and provides a suitable architecture enabling the implementation of a TripleWin solution.
• Pushing the Performance of Biased Neighbor Selection through Biased Unchoking Oechsner, Simon; Lehrieder, Frank; Hoßfeld, Tobias; Metzger, Florian; Pussep, Konstantin; Staehle, Dirk in 9th International Conference on Peer-to-Peer Computing (2009).
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  Locality promotion in P2P content distribution networks is currently a major research topic. One of the goals of all discussed approaches is to reduce the interdomain traffic that causes high costs for ISPs. However, the focus of the work in this field is generally on the type of locality information that is provided to the overlay and on the entities that exchange this information. An aspect that is generally neglected is how this information is used by the peers. In this paper, we consider the predominant approach of Biased Neighbor Selection and compare it with Biased Unchoking, an alternative locality aware peer selection strategy we propose in this paper. We show that both mechanisms complement each other for the BitTorrent file sharing application and achieve the best performance when combined.

  @inproceedings{info3-inproceedings-2009-355, abstract = {Locality promotion in P2P content distribution networks is currently a major research topic. One of the goals of all discussed approaches is to reduce the interdomain traffic that causes high costs for ISPs. However, the focus of the work in this field is generally on the type of locality information that is provided to the overlay and on the entities that exchange this information. An aspect that is generally neglected is how this information is used by the peers. In this paper, we consider the predominant approach of Biased Neighbor Selection and compare it with Biased Unchoking, an alternative locality aware peer selection strategy we propose in this paper. We show that both mechanisms complement each other for the BitTorrent file sharing application and achieve the best performance when combined.}, address = {Seattle, USA}, author = {Oechsner, Simon and Lehrieder, Frank and Hoßfeld, Tobias and Metzger, Florian and Pussep, Konstantin and Staehle, Dirk}, booktitle = {9th International Conference on Peer-to-Peer Computing}, keywords = {sys:hidden:inproceedings}, month = 9, title = {Pushing the Performance of Biased Neighbor Selection through Biased Unchoking}, year = 2009 }

  %0 Conference Paper %1 info3-inproceedings-2009-355 %A Oechsner, Simon %A Lehrieder, Frank %A Hoßfeld, Tobias %A Metzger, Florian %A Pussep, Konstantin %A Staehle, Dirk %B 9th International Conference on Peer-to-Peer Computing %C Seattle, USA %D 2009 %T Pushing the Performance of Biased Neighbor Selection through Biased Unchoking %X Locality promotion in P2P content distribution networks is currently a major research topic. One of the goals of all discussed approaches is to reduce the interdomain traffic that causes high costs for ISPs. However, the focus of the work in this field is generally on the type of locality information that is provided to the overlay and on the entities that exchange this information. An aspect that is generally neglected is how this information is used by the peers. In this paper, we consider the predominant approach of Biased Neighbor Selection and compare it with Biased Unchoking, an alternative locality aware peer selection strategy we propose in this paper. We show that both mechanisms complement each other for the BitTorrent file sharing application and achieve the best performance when combined.
• Pushing the Performance of Biased Neighbor Selection through Biased Unchoking Oechsner, Simon; Lehrieder, Frank; Hoßfeld, Tobias; Metzger, Florian; Pussep, Konstantin; Staehle, Dirk (2009).
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  @techreport{info3-techreport-2009-245, author = {Oechsner, Simon and Lehrieder, Frank and Hoßfeld, Tobias and Metzger, Florian and Pussep, Konstantin and Staehle, Dirk}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 8, number = 459, title = {Pushing the Performance of Biased Neighbor Selection through Biased Unchoking}, year = 2009 }

  %0 Report %1 info3-techreport-2009-245 %A Oechsner, Simon %A Lehrieder, Frank %A Hoßfeld, Tobias %A Metzger, Florian %A Pussep, Konstantin %A Staehle, Dirk %D 2009 %N 459 %T Pushing the Performance of Biased Neighbor Selection through Biased Unchoking
• Measurement of BitTorrent Swarms and their AS Topologies Hoßfeld, Tobias; Hock, David; Oechsner, Simon; Lehrieder, Frank; Despotovic, Zoran; Kellerer, Wolfgang; Michel, Maximilian (2009).
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  @techreport{info3-techreport-2009-246, author = {Hoßfeld, Tobias and Hock, David and Oechsner, Simon and Lehrieder, Frank and Despotovic, Zoran and Kellerer, Wolfgang and Michel, Maximilian}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 11, number = 464, title = {Measurement of BitTorrent Swarms and their AS Topologies}, year = 2009 }

  %0 Report %1 info3-techreport-2009-246 %A Hoßfeld, Tobias %A Hock, David %A Oechsner, Simon %A Lehrieder, Frank %A Despotovic, Zoran %A Kellerer, Wolfgang %A Michel, Maximilian %D 2009 %N 464 %T Measurement of BitTorrent Swarms and their AS Topologies
• PCN-Based Flow Termination with Multiple Bottleneck Links Lehrieder, Frank; Menth, Michael in IEEE International Conference on Communications (ICC) (2009).
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  From the viewpoint of communication networks Network Virtualization (NV) extends beyond pure operational issues and addresses many of the impasses of the current Internet. The idea of Transport Virtualization (TV) progresses the capabilities of NV and enables the independence from a specific network transport resource. The independence is achieved by pooling multiple transport resources and selecting the best resources for exclusive or concurrent use. However, the application and selection of concurrent paths is rather complex and introduces inevitable packet re-ordering due to different stochastic delay characteristics on the used paths. Packets arriving at the destination out-of-order have to be stored in a re-sequencing buffer before reassembled packets are forwarded to the application. Therefore we perform an analysis of the fundamental behaviors and factors for packet re-ordering in concurrent multipath transmissions. This analysis applies analytical and simulative techniques which are used to compute the buffer occupancy probability distribution.

  @inproceedings{info3-inproceedings-2009-337, abstract = {From the viewpoint of communication networks Network Virtualization (NV) extends beyond pure operational issues and addresses many of the impasses of the current Internet. The idea of Transport Virtualization (TV) progresses the capabilities of NV and enables the independence from a specific network transport resource. The independence is achieved by pooling multiple transport resources and selecting the best resources for exclusive or concurrent use. However, the application and selection of concurrent paths is rather complex and introduces inevitable packet re-ordering due to different stochastic delay characteristics on the used paths. Packets arriving at the destination out-of-order have to be stored in a re-sequencing buffer before reassembled packets are forwarded to the application. Therefore we perform an analysis of the fundamental behaviors and factors for packet re-ordering in concurrent multipath transmissions. This analysis applies analytical and simulative techniques which are used to compute the buffer occupancy probability distribution.}, address = {Dresden, Germany}, author = {Lehrieder, Frank and Menth, Michael}, booktitle = {IEEE International Conference on Communications (ICC)}, keywords = {sys:hidden:inproceedings}, month = 6, title = {PCN-Based Flow Termination with Multiple Bottleneck Links}, year = 2009 }

  %0 Conference Paper %1 info3-inproceedings-2009-337 %A Lehrieder, Frank %A Menth, Michael %B IEEE International Conference on Communications (ICC) %C Dresden, Germany %D 2009 %T PCN-Based Flow Termination with Multiple Bottleneck Links %X From the viewpoint of communication networks Network Virtualization (NV) extends beyond pure operational issues and addresses many of the impasses of the current Internet. The idea of Transport Virtualization (TV) progresses the capabilities of NV and enables the independence from a specific network transport resource. The independence is achieved by pooling multiple transport resources and selecting the best resources for exclusive or concurrent use. However, the application and selection of concurrent paths is rather complex and introduces inevitable packet re-ordering due to different stochastic delay characteristics on the used paths. Packets arriving at the destination out-of-order have to be stored in a re-sequencing buffer before reassembled packets are forwarded to the application. Therefore we perform an analysis of the fundamental behaviors and factors for packet re-ordering in concurrent multipath transmissions. This analysis applies analytical and simulative techniques which are used to compute the buffer occupancy probability distribution.
• Marking Conversion for Pre-Congestion Notification Lehrieder, Frank; Menth, Michael in IEEE International Conference on Communications (ICC) (2009).
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  Pre-congestion notification (PCN) defines admissible rates (AR) and supportable rates (SR) per link and marks the PCN traffic rate above these thresholds as AR- or SR-overload. The IETF standardizes simple mechanisms for admission control (AC) and flow termination (FT) based on this PCN-feedback for high-priority DiffServ traffic. While admission control (AC) has been extensively discussed in the literature, flow termination (FT) is a new control function. In this paper we propose an algorithm that converts marked AR-overload into marked SRoverload by unmarking appropriate packets. Classic marked flow termination (MFT) is based on marked SR-overload and works well even with a small number of PCN flows per ingress-egress aggregate and in case of multipath routing. Thanks to the new marking converter MFT also works with marked AR-overload so that a single marking scheme suffices to support AC and FT. We investigate whether MFT with marking conversion based on AR-overload retains the benefits classic MFT.

  @inproceedings{info3-inproceedings-2009-338, abstract = {Pre-congestion notification (PCN) defines admissible rates (AR) and supportable rates (SR) per link and marks the PCN traffic rate above these thresholds as AR- or SR-overload. The IETF standardizes simple mechanisms for admission control (AC) and flow termination (FT) based on this PCN-feedback for high-priority DiffServ traffic. While admission control (AC) has been extensively discussed in the literature, flow termination (FT) is a new control function. In this paper we propose an algorithm that converts marked AR-overload into marked SRoverload by unmarking appropriate packets. Classic marked flow termination (MFT) is based on marked SR-overload and works well even with a small number of PCN flows per ingress-egress aggregate and in case of multipath routing. Thanks to the new marking converter MFT also works with marked AR-overload so that a single marking scheme suffices to support AC and FT. We investigate whether MFT with marking conversion based on AR-overload retains the benefits classic MFT.}, address = {Dresden, Germany}, author = {Lehrieder, Frank and Menth, Michael}, booktitle = {IEEE International Conference on Communications (ICC)}, keywords = {sys:hidden:inproceedings}, month = 6, title = {Marking Conversion for Pre-Congestion Notification}, year = 2009 }

  %0 Conference Paper %1 info3-inproceedings-2009-338 %A Lehrieder, Frank %A Menth, Michael %B IEEE International Conference on Communications (ICC) %C Dresden, Germany %D 2009 %T Marking Conversion for Pre-Congestion Notification %X Pre-congestion notification (PCN) defines admissible rates (AR) and supportable rates (SR) per link and marks the PCN traffic rate above these thresholds as AR- or SR-overload. The IETF standardizes simple mechanisms for admission control (AC) and flow termination (FT) based on this PCN-feedback for high-priority DiffServ traffic. While admission control (AC) has been extensively discussed in the literature, flow termination (FT) is a new control function. In this paper we propose an algorithm that converts marked AR-overload into marked SRoverload by unmarking appropriate packets. Classic marked flow termination (MFT) is based on marked SR-overload and works well even with a small number of PCN flows per ingress-egress aggregate and in case of multipath routing. Thanks to the new marking converter MFT also works with marked AR-overload so that a single marking scheme suffices to support AC and FT. We investigate whether MFT with marking conversion based on AR-overload retains the benefits classic MFT.
• Pre-Congestion Notification (PCN): Lightweight Admission Control and Flow Termination for the Future Internet Menth, Michael; Lehrieder, Frank (2009, June).
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  @misc{info3-tutorial-2009-12, address = {Dresden, Germany}, author = {Menth, Michael and Lehrieder, Frank}, booktitle = {IEEE International Conference on Communications (ICC)}, keywords = {sys:hidden:tutorial}, month = 6, title = {Pre-Congestion Notification (PCN): Lightweight Admission Control and Flow Termination for the Future Internet}, year = 2009 }

  %0 Generic %1 info3-tutorial-2009-12 %A Menth, Michael %A Lehrieder, Frank %B IEEE International Conference on Communications (ICC) %C Dresden, Germany %D 2009 %T Pre-Congestion Notification (PCN): Lightweight Admission Control and Flow Termination for the Future Internet

• Comparison of Marking Algorithms for PCN-Based Admission Control Menth, Michael; Lehrieder, Frank in GI/ITG Conference on Measurement, Modeling, and Evaluation of Computer and Communication Systems (MMB’2008) (2008).
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  @inproceedings{info3-inproceedings-2008-319, address = {Dortmund, Germany}, author = {Menth, Michael and Lehrieder, Frank}, booktitle = {GI/ITG Conference on Measurement, Modeling, and Evaluation of Computer and Communication Systems (MMB'2008)}, keywords = {sys:hidden:inproceedings}, month = 3, title = {Comparison of Marking Algorithms for PCN-Based Admission Control}, year = 2008 }

  %0 Conference Paper %1 info3-inproceedings-2008-319 %A Menth, Michael %A Lehrieder, Frank %B GI/ITG Conference on Measurement, Modeling, and Evaluation of Computer and Communication Systems (MMB'2008) %C Dortmund, Germany %D 2008 %T Comparison of Marking Algorithms for PCN-Based Admission Control
• Performance Evaluation of PCN-Based Admission Control Menth, Michael; Lehrieder, Frank in 16th International Workshop on Quality of Service (IWQoS) (2008).
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  @inproceedings{info3-inproceedings-2008-320, address = {Enschede, Netherlands}, author = {Menth, Michael and Lehrieder, Frank}, booktitle = {16th International Workshop on Quality of Service (IWQoS)}, keywords = {sys:hidden:inproceedings}, month = 6, title = {Performance Evaluation of PCN-Based Admission Control}, year = 2008 }

  %0 Conference Paper %1 info3-inproceedings-2008-320 %A Menth, Michael %A Lehrieder, Frank %B 16th International Workshop on Quality of Service (IWQoS) %C Enschede, Netherlands %D 2008 %T Performance Evaluation of PCN-Based Admission Control
• Investigation of chunk selection strategies in peer-assisted video-on-demand systems Hoßfeld, Tobias; Oechsner, Simon; Lehrieder, Frank; Bergner, Christian; Tran-Gia, Phuoc (2008).
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  @techreport{info3-techreport-2008-235, author = {Hoßfeld, Tobias and Oechsner, Simon and Lehrieder, Frank and Bergner, Christian and Tran-Gia, Phuoc}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 7, number = 446, title = {Investigation of chunk selection strategies in peer-assisted video-on-demand systems}, year = 2008 }

  %0 Report %1 info3-techreport-2008-235 %A Hoßfeld, Tobias %A Oechsner, Simon %A Lehrieder, Frank %A Bergner, Christian %A Tran-Gia, Phuoc %D 2008 %N 446 %T Investigation of chunk selection strategies in peer-assisted video-on-demand systems

• A Priori Detection of Link Overload due to Network Failures Milbrandt, Jens; Menth, Michael; Lehrieder, Frank in Kommunikation in Verteilten Systemen (KiVS) (2007).
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  @inproceedings{info3-inproceedings-2007-256, address = {Bern, Switzerland}, author = {Milbrandt, Jens and Menth, Michael and Lehrieder, Frank}, booktitle = {Kommunikation in Verteilten Systemen (KiVS)}, keywords = {sys:hidden:inproceedings}, month = 2, title = {A Priori Detection of Link Overload due to Network Failures}, year = 2007 }

  %0 Conference Paper %1 info3-inproceedings-2007-256 %A Milbrandt, Jens %A Menth, Michael %A Lehrieder, Frank %B Kommunikation in Verteilten Systemen (KiVS) %C Bern, Switzerland %D 2007 %T A Priori Detection of Link Overload due to Network Failures
• Comparison of Marking Algorithms for PCN-Based Admission Control Menth, Michael; Lehrieder, Frank (2007).
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  @techreport{info3-techreport-2007-227, author = {Menth, Michael and Lehrieder, Frank}, institution = {University of Wuerzburg}, keywords = {sys:hidden:techreport}, month = 10, number = 437, title = {Comparison of Marking Algorithms for PCN-Based Admission Control}, year = 2007 }

  %0 Report %1 info3-techreport-2007-227 %A Menth, Michael %A Lehrieder, Frank %D 2007 %N 437 %T Comparison of Marking Algorithms for PCN-Based Admission Control

• Algorithms for Fast Resilience Analysis in IP Networks Menth, Michael; Milbrandt, Jens; Lehrieder, Frank in 6th IEEE International Workshop on IP Operations and Management (IPOM) (2006).
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  @inproceedings{info3-inproceedings-2006-246, address = {Dublin, Ireland}, author = {Menth, Michael and Milbrandt, Jens and Lehrieder, Frank}, booktitle = {6th IEEE International Workshop on IP Operations and Management (IPOM)}, keywords = {sys:hidden:inproceedings}, month = 10, title = {Algorithms for Fast Resilience Analysis in IP Networks}, year = 2006 }

  %0 Conference Paper %1 info3-inproceedings-2006-246 %A Menth, Michael %A Milbrandt, Jens %A Lehrieder, Frank %B 6th IEEE International Workshop on IP Operations and Management (IPOM) %C Dublin, Ireland %D 2006 %T Algorithms for Fast Resilience Analysis in IP Networks
• A Planning Tool to Improve the Resilience of MPLS Networks Milbrandt, Jens; Menth, Michael; Humm, Korbinian; Lehrieder, Frank; Seufert, Stephan (2006, August).
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  @misc{info3-poster-2006-19, author = {Milbrandt, Jens and Menth, Michael and Humm, Korbinian and Lehrieder, Frank and Seufert, Stephan}, booktitle = {MOP}, keywords = {sys:hidden:poster}, month = 8, title = {A Planning Tool to Improve the Resilience of MPLS Networks}, year = 2006 }

  %0 Generic %1 info3-poster-2006-19 %A Milbrandt, Jens %A Menth, Michael %A Humm, Korbinian %A Lehrieder, Frank %A Seufert, Stephan %B MOP %D 2006 %T A Planning Tool to Improve the Resilience of MPLS Networks