| 1. |
- Arlos, Patrik, et al.
(författare)
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A Distributed Passive Measurement Infrastructure
- 2005
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Konferensbidrag (refereegranskat)abstract
- In this paper we describe a distributed passive measurement infrastructure. Its goals are to reduce the cost and configuration effort per measurement. The infrastructure is scalable with regards to link speeds and measurement locations. A prototype is currently deployed at our university and a demo is online at http://inga.its.bth.se/projects/dpmi. The infrastructure differentiates between measurements and the analysis of measurements, this way the actual measurement equipment can focus on the practical issues of packet measurements. By using a modular approach the infrastructure can handle many different capturing devices. The infrastructure can also deal with the security and privacy aspects that might arise during measurements.
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| 2. |
- Arlos, Patrik, et al.
(författare)
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A Method to Estimate the Timestamp Accuracy of Measurement Hardware and Software Tools
- 2007
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Konferensbidrag (refereegranskat)abstract
- Due to the complex diversity of contemporary Internet applications, computer network measurements have gained considerable interest during the recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc., the quality of these measurements affect the results of these activities and thus the perception of the network and its services. One major source of error is the timestamp accuracy obtained from measurement hardware and software. On this background, we present a method that can estimate the timestamp accuracy obtained from measurement hardware and software. The method is used to evaluate the timestamp accuracy of some commonly used measurement hardware and software. Results are presented for the Agilent J6800/J6830A measurement system, the Endace DAG 3.5E card, the Packet Capture Library (PCAP) either with PF_RING or Memory Mapping, and a RAW socket using either the kernel PDU timestamp (ioctl) or the CPU counter (TSC) to obtain timestamps.
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| 3. |
- Arlos, Patrik, et al.
(författare)
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Accuracy Evaluation of Ping and J-OWAMP
- 2006
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Konferensbidrag (refereegranskat)abstract
- Due to the complex diversity of contemporary Internet services, computer network measurements have gained considerable interest during the recent years. Computer network measurements supply network research, development and operations with data important for network traffic modelling, performance and trend analysis etc. Hence, the quality of these measurements affects the results of these activities and thus the perception of the network and its services. Active measurements are performed by injecting traffic into a network and observing the treatment that this traffic receives. Usually, active measurements are perfomed by writing special applications that act at sender and receiver. These applications are usually executed as user processes. This causes some concern since this can have serious implications on the obtained results, as they are affected by the scheduling mechanisms in the operating system. In this paper, we evaluate the accuracy of two active measurement tools, ping and J-OWAMP, by using high accuracy passive measurements. Our results show that ping is quite accurate, to 0.1~ms for Linux and 1~ms for Windows~XP, while J-OWAMP has a discrepancy of 25~ms plus serious time synchronization problems.
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| 4. |
- Arlos, Patrik
(författare)
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On the Quality of Computer Network Measurements
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Due to the complex diversity of contemporary Internet-services, computer network measurements have gained considerable interest during recent years. Since they supply network research, development and operations with data important for network traffic modelling, performance and trend analysis, etc. The quality of these measurements affect the results of these activities and thus the perception of the network and its services. This thesis contains a systematic investigation of computer network measurements and a comprehensive overview of factors influencing the quality of performance parameters obtained from computer network measurements. This is done using a novel network performance framework consisting of four modules: Generation, Measurement, Analysis and Visualization. These modules cover all major aspects controlling the quality of computer network measurements and thus the validity of all kinds of conclusions based on them. One major source of error is the timestamp accuracy obtained from measurement hardware and software. Therefore, a method is presented that estimates the timestamp accuracy obtained from measurement hardware and software. The method has been used to evaluate the timestamp accuracy of some commonly used hardware (Agilent J6800/J6830A and Endace DAG 3.5E) and software (Packet Capture Library). Furthermore, the influence of analysis on the quality of performance parameters is discussed. An example demonstrates how the quality of a performance metric (bitrate) is affected by different measurement tools and analysis methods. The thesis also contains performance evaluations of traffic generators, how accurately application-level measurements describe network behaviour, and of the quality of performance parameters obtained from PING and J-OWAMP. The major conclusion is that measurement systems and tools must be calibrated, verified and validated for the task of interest before using them for computer network measurements. A guideline is presented on how to obtain performance parameters at a desired quality level.
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| 5. |
- Binzenhöfer, Andreas, et al.
(författare)
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A P2P-based framework for distributed network management
- 2006
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a novel framework supporting distributed network management using a self-organizing peer-to-peer overlay network. The overlay consists of several Distributed Network Agents which can perform distributed tests and distributed monitoring for fault and performance management. In that way, the concept is able to overcome disadvantages that come along with a central management unit, like lack of scalability and reliability. So far, little attention has been payed to the quality of service experienced by the end user. Our self-organizing management overlay provides a reliable and scalable basis for distributed tests that incorporate the end user. The use of a distributed, self-organizing software will also reduce capital and operational expenditures of the operator since fewer entities have to be installed and operated.
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| 6. |
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| 7. |
- Fiedler, Markus, et al.
(författare)
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18th ITC Specialist Seminar on Quality of Experience
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The notion and topic of Quality of Experience (QoE) keeps attracting the attention of manufacturers, operators and researchers. It links user perception and expectations on one side and technical Quality of Service (QoS) parameters, management, pricing schemes etc. on the other side. Such links are needed in order to balance user satisfaction and economic aspects of service provisioning. However, the notion of QoE as such is not without controversy. Technicians, used to a world of objective and clearly definable parameters, tend to fear the subjective, somehow fuzzy parts associated with end user perception. Vice versa, customer relationship and marketing departments might find themselves uncomfortable with technical parameters which might not reflect the user perception in some tense situations. Nevertheless, appearance and utility of a networked service depend on the underlying technical solutions and their performance. Thus, we face the challenge of bringing it all together, which essentially describes the spirit of the 18th ITC Specialists Seminar on Quality of Experience (ITC-SS 18). ITC Specialist Seminars have a very good reputation in gathering experts and their high-quality contributions around a performance-oriented topic of mutual interest. ITC-SS 18 is intended as a meeting place between experts, researchers, practitioners, vendors and customers. It is devoted to presentations and discussions of QoE concepts, analysis, management approaches etc., both from industry and academia. While many conferences are dominated by academia, one third of the submissions to ITC-SS 18 originated from industry. The contributions have been peer-reviewed by at least three independent reviewers and finally, we selected 18 papers to be presented. Additionally, two keynote speeches reflect one industrial and one academic approach to QoE analysis and implementation. For the ITC, the leading conference for performance modeling and analysis of communication networks & systems, ITC-SS 18 opens a window towards the end user. ITC-SS 18 takes place in Karlskrona on May 29—30, 2008. It is organized by the Dept. of Telecommunication Systems (ATS) within the School of Engineering (TEK) at Blekinge Institute of Technology (BTH) in cooperation with the International Advisory Council (IAC) of ITC.
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| 8. |
- Fiedler, Markus, et al.
(författare)
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QoE-based Cross-Layer Design of Mobile Video Systems : Challenges and Concepts
- 2009
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Konferensbidrag (refereegranskat)abstract
- This conceptual paper focuses on revealing challenges and offering concepts associated with the incorporation of the Quality of Experience (QoE) paradigm into the design of mobile video systems. The corresponding design framework combines application, middleware and networking layer in a unique cross-layer approach, in which all layers shall jointly analyse the quality of the video and its delivery in face of volatile conditions. Particular ingredients of the framework are efficient video processing, advanced realtime scheduling, and reduced-reference metrics on application and network layer.
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| 9. |
- Wac, Katarzyna, et al.
(författare)
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Accuracy Evaluation of Application-level Performance Measurements
- 2007
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Konferensbidrag (refereegranskat)abstract
- In many cases, application-level measurements can be the only way for an application to evaluate and adapt to the performance offered by the underlying networks. Applications perceive heterogeneous networking environments spanning over multiple administrative domains as black boxes being inaccessible for lower-level measurement instrumentation. However, application-level measurements can be inaccurate and differ significantly from the lower-level ones, amongst others due to the influence of the protocol stacks. In this paper we quantify and discuss such differences using the DPMI, with Measurement Points instrumented with DAG 3.5E cards for reference link-level measurements. We shed light on various impacts on timestamp accuracy of application-level measurements. Moreover, we quantify the accuracy of generating traffic with constant inter-packet-time. The latter is essential for an accurate emulation of application-level streaming traffic and thus for obtaining realistic end-to-end performance measurements.
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