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Performance of traffic engineering in operational IP-networks: an experimental study
2005 (English)In: 5th IEEE International Workshop on IP Operations and Management, 2005, 202-211 p.Conference paper, Published paper (Refereed)
Abstract [en]

Today, the main alternative for intra-domain traffic engineering in IP networks is to use different methods for setting the weights (and so decide upon the shortest-paths) in the routing protocols OSPF and IS-IS. In this paper we study how traffic engineering perform in real networks. We analyse different weight-setting methods and compare performance with the optimal solution given by a multi-commodity flow optimization problem. Further, we investigate their robustness in terms of how well they manage to cope with estimated traffic matrix data. For the evaluation we have access to net-work topology and traffic data from an operational IP network.

Place, publisher, year, edition, pages
2005. 202-211 p.
Series
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics, ISSN 0302-9743
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-7730DOI: 10.1007/11567486_21ISBN: 978-354029356-9 (print)OAI: oai:DiVA.org:kth-7730DiVA: diva2:12842
Conference
5th IEEE International Workshop on IP Operations and Management, IPOM 2005; Barcelona; 26 October 2005 through 28 October 2005
Note
QC 20101105Available from: 2007-11-25 Created: 2007-11-25 Last updated: 2011-02-11Bibliographically approved
In thesis
1. Towards robust traffic engineering in IP networks
Open this publication in new window or tab >>Towards robust traffic engineering in IP networks
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

To deliver a reliable communication service it is essential for the network operator to manage how traffic flows in the network. The paths taken by the traffic is controlled by the routing function. Traditional ways of tuning routing in IP networks are designed to be simple to manage and are not designed to adapt to the traffic situation in the network. This can lead to congestion in parts of the network while other parts of the network are far from fully utilized. In this thesis we explore issues related to optimization of the routing function to balance load in the network.

We investigate methods for efficient derivation of the traffic situation using link count measurements. The advantage of using link counts is that they are easily obtained and yield a very limited amount of data. We evaluate and show that estimation based on link counts give the operator a fast and accurate description of the traffic demands. For the evaluation we have access to a unique data set of complete traffic demands from an operational IP backbone.

Furthermore, we evaluate performance of search heuristics to set weights in link-state routing protocols. For the evaluation we have access to complete traffic data from a Tier-1 IP network. Our findings confirm previous studies that use partial traffic data or synthetic traffic data. We find that optimization using estimated traffic demands has little significance to the performance of the load balancing.

Finally, we device an algorithm that finds a routing setting that is robust to shifts in traffic patterns due to changes in the interdomain routing. A set of worst case scenarios caused by the interdomain routing changes is identified and used to solve a robust routing problem. The evaluation indicates that performance of the robust routing is close to optimal for a wide variety of traffic scenarios.

The main contribution of this thesis is that we demonstrate that it is possible to estimate the traffic matrix with good accuracy and to develop methods that optimize the routing settings to give strong and robust network performance. Only minor changes might be necessary in order to implement our algorithms in existing networks.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. xi, 36 p.
Series
Trita-EE, ISSN 1653-5146 ; 2007:073
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-4557 (URN)978-91-7178-816-0 (ISBN)
Presentation
2007-12-10, Q31, KTH, Osquldas väg 6, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20101105Available from: 2007-11-25 Created: 2007-11-25 Last updated: 2010-11-05Bibliographically approved
2. Aspects of proactive traffic engineering in IP networks
Open this publication in new window or tab >>Aspects of proactive traffic engineering in IP networks
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To deliver a reliable communication service over the Internet it is essential for the network operator to manage the traffic situation in the network. The traffic situation is controlled by the routing function which determines what path traffic follows from source to destination.  Current practices for setting routing parameters in IP networks are designed to be simple to manage. This can lead to congestion in parts of the network while other parts of the network are far from fully utilized. In this thesis we explore issues related to optimization of the routing function to balance load in the network and efficiently deliver a reliable communication service to the users. The optimization takes into account not only the traffic situation under normal operational conditions, but also traffic situations that appear under a wide variety of circumstances deviating from the nominal case. In order to balance load in the network knowledge of the traffic situations is needed. Consequently, in this thesis we investigate methods for efficient derivation of the traffic situation. The derivation is based on estimation of traffic demands from link load measurements. The advantage of using link load measurements is that they are easily obtained and consist  of a limited amount of data that need to be processed. We evaluate and demonstrate how estimation based on link counts gives the operator a fast and accurate description of the traffic demands. For the evaluation we have access to a unique data set of complete traffic demands from an operational IP backbone.  However, to honor service level agreements at all times the variability of the traffic needs to be accounted for in the load balancing. In addition, optimization techniques are often sensitive to errors and variations in input data. Hence, when an optimized routing setting is subjected to real traffic demands in the network, performance often deviate from what can be anticipated from the optimization. Thus, we identify and model different traffic uncertainties and describe how the routing setting can be optimized, not only for a nominal case, but for a wide range of different traffic situations that might appear in the network.  Our results can be applied in MPLS enabled networks as well as in networks using link state routing protocols such as the widely used OSPF and IS-IS protocols. Only minor changes may be needed in current networks to implement our algorithms. The contributions of this thesis is that we: demonstrate that it is possible to estimate the traffic matrix with acceptable precision, and we develop methods and models for common traffic uncertainties to account for these uncertainties in the optimization of the routing configuration. In addition, we identify important properties in the structure of the traffic to successfully balance uncertain and varying traffic demands.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. xi, 63 p.
Series
Trita-EE, ISSN 1653-5146
National Category
Control Engineering
Identifiers
urn:nbn:se:kth:diva-29558 (URN)978-91-7415-870-0 (ISBN)
Public defence
2011-03-01, F3, Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Supervisors
Note
QC 20110211Available from: 2011-02-11 Created: 2011-02-07 Last updated: 2011-02-11Bibliographically approved

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