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Interdomain Traffic Engineering for Multi-homed NetworksGao, Ruomei 24 August 2007 (has links)
Interdomain traffic engineering (TE) controls the flow of traffic
between autonomous systems (ASes) to achieve performance goals under
various resource constraints. Interdomain TE can be categorized
into ingress TE and egress TE, which aim to control the ingress and
egress traffic flow in a network, respectively. Most interdomain TE
techniques are based on BGP, which was not designed to support
performance based routing. Hence even though some basic interdomain
TE techniques are widely deployed, their overall effectiveness and
impact on interdomain traffic are not well understood. Furthermore,
systematic practices for deploying these techniques have yet to be
developed.
In this thesis, we explore these open issues for both ingress and
egress TE. We first focus on the AS-Path prepending technique in
interdomain ingress TE. We design a polynomial algorithm that
takes network settings as input and produces the optimal prepending
at each ingress link. We also develop methods to measure the inputs
of the optimal algorithm by leveraging widely available looking
glass severs and evaluate the errors of such measurement. We
further propose an algorithm, based on this optimal algorithm, that
is robust to input errors.
We then focus on Intelligent Routing Control (IRC) systems often
used at multihomed networks for egress interdomain TE. To address
the possible traffic oscillation problem caused by multiple IRC
systems, we design a class of randomized IRC algorithms. Through
simulations, we show that the proposed algorithms can effectively
mitigate oscillations. We also show that IRC systems using
randomized path switching algorithms perform better than those
switching path deterministically, when both types of IRC systems
co-exist.
To further understand the performance impact of IRC systems, we next
focus on the performance of applications, such as TCP
connections. We study the synergistic and antagonistic
interactions between IRC and TCP connections, through a simple
dual-feedback model. We first examine the impact of sudden RTT and
available bandwidth changes in TCP connection. We then examine the
effect of IRC measurement delays on closed loop traffic. We also
show the conditions under which IRC is beneficial under various path
impairment models.
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A Dynamic Recovery with Mixed Local/Global Repair for Real-Time Multimedia Traffic on MPLS NetworksChiang, Yung-Hsien 26 August 2004 (has links)
In this Thesis, we present a fault recovery mechanism by considering both local and global repairs for real-time traffic conveyed over MPLS networks. To meet the end-to-end time constraints of real-time traffic flows, once a link failure occurs, the real-time packets are sent via the most nearby local repair path if one can be identified, while at the same time the probe packets are sent to the Egress router over every possible local repair paths. By monitoring all of the incoming probe packets, the Egress router can determine which path is the most suitable repair path using the minimum-delay-deviation criterion and then sends out all the remaining packets over the new path. To fulfill the delay requirements of real-time flows whenever link failures occur, the probe packets need to be periodically sent out to reflect the dynamic change of traffic loads on the pre-established LSPs.
The simulation results, after running on the MSN, have demonstrated that our recovery scheme not only forwards the packets of real-time flows in time over the local repair paths, but also prevents them from possible out-of-order situations. Besides, the proposed scheme of dynamic rerouting assist us in achieving the end-to-end delay guarantee for real-time traffic on MPLS networks.
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An Integrated Incident Detection Methodology With Gps-equipped VehiclesDemiroluk, Sami 01 August 2007 (has links) (PDF)
Recurrent congestion in urban traffic networks, especially on arterials, is a growing problem. Non-recurrent congestion, mainly due to incidents, only aggravates the problem. Any solution requires monitoring of the network, for which many
developing countries, such as Turkey, do not have the traditional surveillance systems on arterials mainly due to high costs. An alternative solution is the utilization of Global Positioning System (GPS) technology, which is increasingly
used in traffic monitoring. It is easy and cheap to obtain the GPS track information,even in real-time, from a probe-vehicle or a fleet of vehicles / and spatial variation of speed and travel time of the vehicle(s) in a network can be determined. GPS-based data, especially with only one probe-vehicle, would not provide information on the concurrent states of upstream and downstream traffic, needed to define the state of traffic in a network. To overcome this obstacle, a methodology based on statistical analysis of archival traffic conditions obtained through different sources is proposed
to analyze traffic fluctuations and identify daily traffic pattern. As a result, bottleneck and resulting queues can be detected on a corridor. Thus, it enables detection of recurrent
congestion and queues that may result from incidents.
The proposed methodology is tested on a corridor the roadway between METU and Kizilay of inö / nü / Boulevard. The results show that the methodology can effectively identify bottleneck locations on the corridor and also an incident observed during the data collection is detected correctly by the proposed algorithm.
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An Effective Traffic-Reroute Scheme with Reverse Labeling in MPLS NetworksLin, Kai-Han 01 August 2003 (has links)
MPLS, a next generation backbone architecture, can speed up packet forwarding to destination by label switching. However, if there exists no backup LSP when the primary LSP fails, MPLS frames cannot be forwarded to destination. Therefore, fault recovery has become an important research area in MPLS Traffic Engineering. Makam approach and Haskin approach are the most famous two among the previous literatures. Besides, IETF has made strict definitions for MPLS Recovery in RFC 3469 in February, 2003.
We propose a Reverse Labeling Scheme to handle fault recovery in this thesis. We establish a virtual reverse LSP along the completely reverse direction of the primary path. When there is a link failure in the primary LSP, LSR will forward packets back to Ingress by virtual reverse LSP instead of using the primary LSP. This idea of building virtual reverse LSP makes Haskin approach practical in implementation. In addition, we save network resources by designing a scheme such that LSR is easier to convert from the primary LSP to the backup LSP. In order to solve the out-of-order packets in Haskin approach, Hundessa adds buffering on every LSR. The buffer can temporarily store the packets once a link failure has been detected. By adopting the basic idea of Hundessa approach, we embed our Reverse Labeling Scheme and implement it on Linux platform. We also make some modifications to solve the buffering problems.
Finally, we demonstrate this Reverse Labeling Scheme by several experiments. We not only show the low packet loss rate, but also solve the packet out-of-order problems. The significant decrease of out-of-order packets can further improve the efficiency of TCP flow transmission.
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An investigation of bluetooth technology for measuring travel times on arterial roads: a case study on spring streetVo, Trung 05 April 2011 (has links)
Research in the field of travel time measurement using Bluetooth technology has been an area of great interest in recent years as transportation professionals strive to increase the cost-effectiveness, accuracy, anonymity, and safety of travel time data collection methods. Commonly used travel time data collection methods include the use of inductive loops, video cameras, and probe vehicles. However, Bluetooth, a globally accepted wireless technology, serves as the medium being utilized by more and more transportation consultants, public agencies, and academics in the collection of travel time data. This study seeks to develop a methodology for measuring travel times on arterial roads using Bluetooth technology. A literature review of general travel time methods and Bluetooth travel time methods was conducted to provide the context for a Bluetooth field deployment development and implementation. The study presents the deployment plan and data analysis of a case study conducted on Spring Street in Atlanta, Georgia. Variable heights, Bluetooth to Bluetooth interference, and detection of Bluetooth devices in probe vehicles are investigated and recommendations are suggested for future Bluetooth travel time studies.
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Arterial roadway traffic data collection using bluetooth technologyBox, Stephanie 29 August 2011 (has links)
The use of Bluetooth technology for gathering traffic data is becoming
increasingly popular due to the large volume of data that can be gathered at a relatively
low cost. The limited number of devices in discoverable mode and potential long
discovery time of the Bluetooth devices creates an opportunity for evaluating the sensor
array setup that can maximize the sample of devices identified. This thesis investigates
several factors that have a significant impact on the quality of the data obtained using
Bluetooth, including the number of Bluetooth readers, orientation of the Bluetooth
antennas, position of the readers relative to one another, and the location of the Bluetooth
stations.
The thesis begins with an overview of Bluetooth technology and literature review
on the use of Bluetooth in previous traffic studies. Next, the methodology for the setup of
the Bluetooth system and the four tests performed to evaluate the factors affecting the
quality of the data are described. Through the results of these tests, it was observed that a
"flat" antenna orientation allows for the greatest detection range and that the walls of
buildings can prevent detection of Bluetooth devices inside the buildings. In addition,
using multiple Bluetooth readers per sensor array resulted in statistically significant
increases in number of detections of single reader sensors, and horizontally separated
sensor arrays were observed to be more effective than vertically separated sensor arrays.
Finally, the thesis concludes with a summary of findings and a discussion of further
research needs.
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Stochastic dynamic traffic assignment for intermodal transportation networks with consistent information supply strategiesAbdelghany, Khaled Faissal Said, January 2001 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from Dissertation Abstracts.
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Algorithms for estimating mean vehicle speed using uncalibrated traffic management cameras /Schoepflin, Todd Nelson. January 2003 (has links)
Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 245-249).
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Electrical circuit simulation of traffic flowFurber, Conan Paul, 1936- January 1973 (has links)
No description available.
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Dynamic control of traffic input into an urban complexRabin, William David, 1941- January 1967 (has links)
No description available.
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