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| 3. |
- Melander, Bob, et al.
(författare)
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Trace-Driven Network Path Emulation
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper reports on on-going work where a trace-driven approach to network path emulation is investigated. Time stamped probe packets are sent along a network path whereby a probe packet trace can be generated. It basically contains the send times and the one-way delays/loss indications of the probe packets. Inside the emulator, the probe packet trace is used by a loss model and a delay model. These determine if a packet should be dropped or what the delay of the packet should be. Three loss models and three delay models are evaluated. For non-responsive UDP-based flows, the trace-driven loss and delay models that determine loss and delay based on loss-rates and delay distribution parameters calculated across the probe packet trace using a small gliding window are found to perform best. For adaptive TCP flows, none of the evaluated trace-driven models performs well. Instead, the Bernoulli loss model and an independent average delay model performs best.
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| 4. |
- Björkman, Mats, et al.
(författare)
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Impact of the Ethernet capture effect on bandwidth measurements
- 2000
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Ingår i: NETWORKING 2000. - 0302-9743. ; 1815, s. 156-167
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present impacts of the Ethernet capture effect on bandwidth measurements. We show that the unfairness caused by the Ethernet capture effect can have a severe impact on the ability to estimate available bandwidth. We define two metrics, su
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| 5. |
- Ekelin, Svante, et al.
(författare)
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Real-Time Measurement of End-to-End Available Bandwidth using Kalman Filtering
- 2006
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Ingår i: 10th IEEE/IFIP Network Operations and Management Symposium, 2006. NOMS 2006.. - Piscataway, New Jersey, USA : IEEE Computer Society. - 1424401429 - 9781424401420 ; , s. 73-84
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Konferensbidrag (refereegranskat)abstract
- This paper presents a new method, BART (bandwidth available in real-time), for estimating the end-to-end available bandwidth over a network path. It estimates bandwidth quasi-continuously, in real-time. The method has also been implemented as a tool. It relies on self-induced congestion, and repeatedly samples the available bandwidth of the network path with sequences of probe packet pairs, sent at randomized rates. BART requires little computation in each iteration, is lightweight with respect to memory requirements, and adds only a small amount of probe traffic. The BART method uses Kalman filtering, which enables real-time estimation (a.k.a. tracking). It maintains a current estimate, which is incrementally improved with each new measurement of the inter-packet time separations in a sequence of probe packet pairs. The measurement model has a strong non-linearity, and would not at first sight be considered suitable for Kalman filtering, but we show how this non-linearity can be handled. BART may be tuned according to the specific needs of the measurement application, such as agility vs. stability of the estimate. We have tested an implementation of BART in a physical test network with carefully controlled cross traffic, with good accuracy and agreement. Test measurements have also been performed over the Internet. We compare the performance of BART with that of pathChirp, a state-of-the-art tool for measuring end-to-end available bandwidth in real-time
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| 6. |
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| 7. |
- Ekelin, Svante, et al.
(författare)
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Real-time measurement of end-to-end available bandwidth using Kalman filtering
- 2006. - 1
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Konferensbidrag (refereegranskat)abstract
- This paper presents a new method, BART (Bandwidth Available in Real-Time), for estimating the end-to-end available bandwidth over a network path. It estimates bandwidth quasi-continuously, in real-time. The method has also been implemented as a tool. It relies on self-induced congestion, and probes the network path with trains of probe packets, sent at randomized rates. BART requires little computation in each iteration, is light-weight with respect to memory requirements, and adds only a small amount of probe traffic. The BART method is based on Kalman filtering, which enables real-time estimation (a.k.a. tracking) with optimum performance under general conditions. It maintains a current estimate, which is incrementally improved with each new measurement of the inter-packet time separations in a probe packet train. The measurement model has a strong non-linearity, and would not at first sight be considered suitable for Kalman filtering, but we show how this non-linearity can be handled. BART may be tuned according to the specific needs of the measurement application, such as agility vs. stability of the estimate, and the desired time-scale on which to track traffic fluctuations. We have tested BART in a physical test network with carefully controlled cross traffic, with good accuracy and agreement. Test measurements have also been performed over the Internet. We compare the performance of BART with that of pathChirp, a state-of-the-art tool for measuring end-to-end available bandwidth in real-time.
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| 8. |
- Johnsson, Andreas, et al.
(författare)
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An Analysis of Active End-to-end Bandwidth Measurement Methods in Wireless Networks
- 2006
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Ingår i: E2EMON 06: 4th IEEE/IFIP Workshop on End-to-End Monitoring Techniques and Services: REAL-TIME MONITORING OF INTERNET PATHS. - 9781424401451 ; , s. 75-82
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- For active, probing-based bandwidth measurements performed on top of the unifying IP layer, it may seem reasonable to expect the measurement problem in wireless networks to be no different than the one in wired networks. However, in networks with 802.11 wireless bottleneck links we show that this is not the case. The results from the experiments presented in this paper show that the measured available bandwidth is dependent on the probe packet size (contrary to what is observed in wired networks). Another equally important finding is that the measured link capacity, using the well known TOPP model, is dependent on the probe packet size and on the cross-traffic intensity. The underlying reasons for the observed differences are analyzed by incorporating the characteristics of 802.11 wireless networks into the TOPP model. The extended model is applicable to other end-to-end bandwidth measurement methods as well, such as BART, Pathload and PTR.
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| 9. |
- Johnsson, Andreas, et al.
(författare)
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Bandwidth measurement in wireless networks
- 2006
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Ingår i: IFIP International Federation for Information Processing. - Boston, MA : Springer US. - 0387311718 - 9780387311715 ; , s. 89-98
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Konferensbidrag (refereegranskat)abstract
- For active, probing-based bandwidth measurements performed on top of the unifying IP layer, it may seem reasonable to expect the measurement problem in wireless networks, such as ad-hoc networks, to be no different than the one in wired networks. However, in networks with 802.11 wireless links we show that this is not the case. Our experiments show that the measured available bandwidth is dependent on the probe packet size (contrary to what is observed in wired networks). Another equally important finding is that the measured link capacity is dependent on the probe packet size and on the cross-traffic intensity. The study we present has been performed using a bandwidth measurement tool, DietTopp, that is based on the previously not implemented TOPP method. DietTopp measures the end-to-end available bandwidth of a network path along with the capacity of the congested link.
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| 10. |
- Johnsson, Andreas, 1977-
(författare)
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Modeling, Implementation and Evaluation of IP Network Bandwidth Measurement Methods
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Internet has gained much popularity among the public since the mid 1990's and is now an integrated part of our society. A large range of high-speedbroadband providers and the development of new and more efficient Internet applications increase the possibilities to watch movies and live TV, use IP-telephony and share files over the Internet. Such applications demand high data transmission rates, which in turn consume network bandwidth. Since several users must share the common bandwidth capacity on the Internet, there will be locations in the network where the demand is higher than the capacity. This causes network congestion, which has negative impact on both the data transmission rate and transmission quality.This thesis is about methods for measuring the available bandwidth of a network path between two computers. The available bandwidth can be interpreted as the maximum transfer rate possible without causing congestion. By deploying the methods studied in this thesis the available bandwidth can be measured without previous knowledge of the network topology. When an estimate of the available bandwidth is obtained, the transfer rate when sending messages between computers can be set to the measured value in order to avoid congestion.In the thesis an active end-to-end available bandwidth measurement method called "Bandwidth Available in Real Time" (BART for short) is evaluated. BART measures the available bandwidth by injecting probe packets into the network at a given rate and then analysing how this rate has changed on the receiving side. A Kalman filter is used to update the current estimate of the available bandwidth using the new measurement sample.The focus of the thesis is on how methods, such as BART, function in wireless 802.11 networks, which are very popular in work as well as in home environments. Wireless networks have a different construction compared to many other types of networks and this can affect the accuracy of the measurement methods discussed in this thesis. The effects must be analyzed and understood in order to obtain accurate available bandwidth estimates. Since wireless links are often parts of the network path between a sender and a receiver on the Internet, it is important to study how these links affect the estimates of the available bandwidth.
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