432 research outputs found
Combined Intra- and Inter-domain Traffic Engineering using Hot-Potato Aware Link Weights Optimization
A well-known approach to intradomain traffic engineering consists in finding
the set of link weights that minimizes a network-wide objective function for a
given intradomain traffic matrix. This approach is inadequate because it
ignores a potential impact on interdomain routing. Indeed, the resulting set of
link weights may trigger BGP to change the BGP next hop for some destination
prefixes, to enforce hot-potato routing policies. In turn, this results in
changes in the intradomain traffic matrix that have not been anticipated by the
link weights optimizer, possibly leading to degraded network performance.
We propose a BGP-aware link weights optimization method that takes these
effects into account, and even turns them into an advantage. This method uses
the interdomain traffic matrix and other available BGP data, to extend the
intradomain topology with external virtual nodes and links, on which all the
well-tuned heuristics of a classical link weights optimizer can be applied. A
key innovative asset of our method is its ability to also optimize the traffic
on the interdomain peering links. We show, using an operational network as a
case study, that our approach does so efficiently at almost no extra
computational cost.Comment: 12 pages, Short version to be published in ACM SIGMETRICS 2008,
International Conference on Measurement and Modeling of Computer Systems,
June 2-6, 2008, Annapolis, Maryland, US
Cautious Weight Tuning for Link State Routing Protocols
Link state routing protocols are widely used for intradomain routing in the Internet. These protocols are simple to administer and automatically update paths between sources and destinations when the topology changes. However, finding link weights that optimize network performance for a given traffic scenario is computationally hard. The situation is even more complex when the traffic is uncertain or time-varying. We present an efficient heuristic for finding link settings that give uniformly good performance also under large changes in the traffic. The heuristic combines efficient search techniques with a novel objective function. The objective function combines network performance with a cost of deviating from desirable features of robust link weight settings. Furthermore, we discuss why link weight optimization is insensitive to errors in estimated traffic data from link load measurements. We assess performance of our method using traffic data from an operational IP backbone
Time-efficient algorithms for BGP route configuration
Based on the concept of most popular prefix first, two efficient algorithms for BGP route configuration are proposed. The first algorithm MPPF_SES is designed for solving the single egress selection (SES) problem, and the second algorithm MPPF_MES is for multiple egress selection (MES). MPPF_MES has two variants, one aims at minimizing the total amount of resources consumed for carrying the transit traffic, and the other tries to minimize the egress link capacity required. Compared with the existing algorithms, a comparable performance in terms of network resources consumed can be obtained. In case of SES, our MPPF_SES can carry a given traffic load with much lower egress link capacity requirement. In case of MES, our MPPF_MES tends to provide a more stable performance. Last but not the least, our proposed algorithms have a much lower time complexity than the existing approach.published_or_final_versio
A Survey of Network Optimization Techniques for Traffic Engineering
TCP/IP represents the reference standard for the implementation of interoperable communication networks. Nevertheless, the layering principle at the basis of interoperability severely limits the performance of data communication networks, thus requiring proper configuration and management in order to provide effective management of traffic flows. This paper presents a brief survey related to network optimization using Traffic Engineering algorithms, aiming at providing additional insight to the different alternatives available in the scientific literature
Time-efficient algorithms for BGP route configuration
Based on the concept of most popular prefix first, two efficient algorithms for BGP route configuration are proposed. The first algorithm MPPF_SES is designed for solving the single egress selection (SES) problem, and the second algorithm MPPF_MES is for multiple egress selection (MES). MPPF_MES has two variants, one aims at minimizing the total amount of resources consumed for carrying the transit traffic, and the other tries to minimize the egress link capacity required. Compared with the existing algorithms, a comparable performance in terms of network resources consumed can be obtained. In case of SES, our MPPF_SES can carry a given traffic load with much lower egress link capacity requirement. In case of MES, our MPPF_MES tends to provide a more stable performance. Last but not the least, our proposed algorithms have a much lower time complexity than the existing approach.published_or_final_versio
Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results
Fixed and mobile telecom operators, enterprise network operators and cloud
providers strive to face the challenging demands coming from the evolution of
IP networks (e.g. huge bandwidth requirements, integration of billions of
devices and millions of services in the cloud). Proposed in the early 2010s,
Segment Routing (SR) architecture helps face these challenging demands, and it
is currently being adopted and deployed. SR architecture is based on the
concept of source routing and has interesting scalability properties, as it
dramatically reduces the amount of state information to be configured in the
core nodes to support complex services. SR architecture was first implemented
with the MPLS dataplane and then, quite recently, with the IPv6 dataplane
(SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering
of packets across nodes to a general network programming approach, making it
very suitable for use cases such as Service Function Chaining and Network
Function Virtualization. In this paper we present a tutorial and a
comprehensive survey on SR technology, analyzing standardization efforts,
patents, research activities and implementation results. We start with an
introduction on the motivations for Segment Routing and an overview of its
evolution and standardization. Then, we provide a tutorial on Segment Routing
technology, with a focus on the novel SRv6 solution. We discuss the
standardization efforts and the patents providing details on the most important
documents and mentioning other ongoing activities. We then thoroughly analyze
research activities according to a taxonomy. We have identified 8 main
categories during our analysis of the current state of play: Monitoring,
Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path
Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL
Carbon-Intelligent Global Routing in Path-Aware Networks
The growing energy consumption of Information and Communication Technology
(ICT) has raised concerns about its environmental impact. However, the carbon
efficiency of data transmission over the Internet has so far received little
attention. This carbon efficiency can be enhanced effectively by sending
traffic over carbon-efficient inter-domain paths. However, challenges in
estimating and disseminating carbon intensity of inter-domain paths have
prevented carbon-aware path selection from becoming a reality.
In this paper, we take advantage of path-aware network architectures to
overcome these challenges. In particular, we design CIRo, a system for
forecasting the carbon intensity of inter-domain paths and disseminating them
across the Internet. We implement a proof of concept for CIRo on the codebase
of the SCION path-aware Internet architecture and test it on the SCIONLab
global research testbed. Further, we demonstrate the potential of CIRo for
reducing the carbon footprint of endpoints and end domains through large-scale
simulations. We show that CIRo can reduce the carbon intensity of
communications by at least 47% for half of the domain pairs and the carbon
footprint of Internet usage by at least 50% for 87% of end domains
Scalable BGP Prefix Selection for Effective Inter-domain Traffic Engineering
Inter-domain Traffic Engineering for multi-homed networks faces a scalability
challenge, as the size of BGP routing table continue to grow. In this context,
the choice of the best path must be made potentially for each destination
prefix, requiring all available paths to be characterised (e.g., through
measurements) and compared with each other. Fortunately, it is well-known that
a few number of prefixes carry the larger part of the traffic. As a natural
consequence, to engineer large volume of traffic only few prefixes need to be
managed. Yet, traffic characteristics of a given prefix can greatly vary over
time, and little is known on the dynamism of traffic at this aggregation level,
including predicting the set of the most significant prefixes in the near
future. %based on past observations. Sophisticated prediction methods won't
scale in such context. In this paper, we study the relationship between prefix
volume, stability, and predictability, based on recent traffic traces from nine
different networks. Three simple and resource-efficient methods to select the
prefixes associated with the most important foreseeable traffic volume are then
proposed. Such proposed methods allow to select sets of prefixes with both
excellent representativeness (volume coverage) and stability in time, for which
the best routes are identified. The analysis carried out confirm the potential
benefits of a route decision engine
Towards Robust Traffic Engineering in IP Networks
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 is
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 who 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
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