756 research outputs found
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
Prediction-based Decentralized Routing Algorithm
We introduce a new efficient routing algorithm called Prediction-based Decentralized Routing algorithm (PDR), which is based on the Ant Colony Optimization (ACO) meta-heuristics. In our approach, an ant uses a combination of the link state information and the predicted link load instead of the ant's trip time to determine the amount of pheromone to deposit. A Feed Forward Neural Network (FFNN) is used to build adaptive traffic predictors which capture the actual traffic behaviour. We study two performance parameters: the rejection ratio and the percentage of accepted bandwidth under two different network load conditions. We show that our algorithm reduces the rejection ratio of requests and achieves a higher throughput when compared to Shortest Path First and Widest Shortest Path algorithms
Energy management in communication networks: a journey through modelling and optimization glasses
The widespread proliferation of Internet and wireless applications has
produced a significant increase of ICT energy footprint. As a response, in the
last five years, significant efforts have been undertaken to include
energy-awareness into network management. Several green networking frameworks
have been proposed by carefully managing the network routing and the power
state of network devices.
Even though approaches proposed differ based on network technologies and
sleep modes of nodes and interfaces, they all aim at tailoring the active
network resources to the varying traffic needs in order to minimize energy
consumption. From a modeling point of view, this has several commonalities with
classical network design and routing problems, even if with different
objectives and in a dynamic context.
With most researchers focused on addressing the complex and crucial
technological aspects of green networking schemes, there has been so far little
attention on understanding the modeling similarities and differences of
proposed solutions. This paper fills the gap surveying the literature with
optimization modeling glasses, following a tutorial approach that guides
through the different components of the models with a unified symbolism. A
detailed classification of the previous work based on the modeling issues
included is also proposed
Robust routing
In a network, traffic demands are known with a degree of uncertainty, traffic engineering should take into account the traffic variability. In this research work we focus on the robust routing under changing network conditions. Daily Internet traffic pattern shows that network is vulnerable to malicious attacks, denial of service attacks, worms and viruses. Oblivious routing has a substantially better performance than open shortest path first [OSPF] routing for different level of uncertainty. We propose a theoretical framework for Robust Routing aiming to improve online and offline traffic engineering approaches
Towards cognitive in-operation network planning
Next-generation internet services such as live TV and video on demand require high bandwidth and ultra-low latency. The ever-increasing volume, dynamicity and stringent requirements of these services’ demands are generating new challenges to nowadays telecom networks. To decrease expenses, service-layer content providers are delivering their content near the end users, thus allowing a low latency and tailored content delivery. As a consequence of this, unseen metro and even core traffic dynamicity is arising with changes in the volume and direction of the traffic along the day.
A tremendous effort to efficiently manage networks is currently ongoing towards the realisation of 5G networks. This translates in looking for network architectures supporting dynamic resource allocation, fulfilling strict service requirements and minimising the total cost of ownership (TCO). In this regard, in-operation network planning was recently proven to successfully support various network reconfiguration use cases in prospective scenarios. Nevertheless, additional research to extend in-operation planning capabilities from typical reactive optimization schemes to proactive and predictive schemes based on the analysis of network monitoring data is required.
A hot topic raising increasing attention is cognitive networking, where an elevated knowledge about the network could be obtained as a result of introducing data analytics in the telecom operator’s infrastructure. By using predictive knowledge about the network traffic, in-operation network planning mechanisms could be enhanced to efficiently adapt the network by means of future traffic prediction, thus achieving cognitive in-operation network planning.
In this thesis, we focus on studying mechanisms to enable cognitive in-operation network planning in core networks. In particular, we focus on dynamically reconfiguring virtual network topologies (VNT) at the MPLS layer, covering a number of detailed objectives. First, we start studying mechanisms to allow network traffic flow modelling, from monitoring and data transformation to the estimation of predictive traffic model based on this data. By means of these traffic models, then we tackle a cognitive approach to periodically adapt the core VNT to current and future traffic, using predicted traffic matrices based on origin-destination (OD) predictive models. This optimization approach, named VENTURE, is efficiently solved using dedicated heuristic algorithms and its feasibility is demonstrated in an experimental in-operation network planning environment. Finally, we extend VENTURE to consider core flows dynamicity as a result of metro flows re-routing, which represents a meaningful dynamic traffic scenario. This extension, which entails enhancements to coordinate metro and core network controllers with the aim of allowing fast adaption of core OD traffic models, is evaluated and validated in terms of traffic models accuracy and experimental feasibility.Els serveis d’internet de nova generaciĂł tals com la televisiĂł en viu o el vĂdeo sota demanda requereixen d’un gran ample de banda i d’ultra-baixa latència. L’increment continu del volum, dinamicitat i requeriments d’aquests serveis estĂ generant nous reptes pels teleoperadors de xarxa. Per reduir costs, els proveĂŻdors de contingut estan disposant aquests mĂ©s a prop dels usuaris finals, aconseguint aixĂ una entrega de contingut feta a mida. ConseqĂĽentment, estem presenciant una dinamicitat mai vista en el trĂ fic de xarxes de metro amb canvis en la direcciĂł i el volum del trĂ fic al llarg del dia. Actualment, s’estĂ duent a terme un gran esforç cap a la realitzaciĂł de xarxes 5G. Aquest esforç es tradueix en cercar noves arquitectures de xarxa que suportin l’assignaciĂł dinĂ mica de recursos, complint requeriments de servei estrictes i minimitzant el cost total de la propietat. En aquest sentit, recentment s’ha demostrat com l’aplicaciĂł de “in-operation network planning” permet exitosament suportar diversos casos d’ús de reconfiguraciĂł de xarxa en escenaris prospectius. No obstant, Ă©s necessari dur a terme mĂ©s recerca per tal d’estendre “in-operation network planning” des d’un esquema reactiu d’optimitzaciĂł cap a un nou esquema proactiu basat en l’analĂtica de dades provinents del monitoritzat de la xarxa. El concepte de xarxes cognitives es tambĂ© troba al centre d’atenciĂł, on un elevat coneixement de la xarxa s’obtindria com a resultat d’introduir analĂtica de dades en la infraestructura del teleoperador. Mitjançant un coneixement predictiu sobre el trĂ fic de xarxa, els mecanismes de in-operation network planning es podrien millorar per adaptar la xarxa eficientment basant-se en predicciĂł de trĂ fic, assolint aixĂ el que anomenem com a “cognitive in-operation network Planning”. En aquesta tesi ens centrem en l’estudi de mecanismes que permetin establir “el cognitive in-operation network Planning” en xarxes de core. En particular, ens centrem en reconfigurar dinĂ micament topologies de xarxa virtual (VNT) a la capa MPLS, cobrint una sèrie d’objectius detallats. Primer comencem estudiant mecanismes pel modelat de fluxos de trĂ fic de xarxa, des del seu monitoritzat i transformaciĂł fins a l’estimaciĂł de models predictius de trĂ fic. Posteriorment, i mitjançant aquests models predictius, tractem un esquema cognitiu per adaptar periòdicament la VNT utilitzant matrius de trĂ fic basades en predicciĂł de parells origen-destĂ (OD). Aquesta optimitzaciĂł, anomenada VENTURE, Ă©s resolta eficientment fent servir heurĂstiques dedicades i Ă©s posteriorment avaluada sota escenaris de trĂ fic de xarxa dinĂ mics. A continuaciĂł, estenem VENTURE considerant la dinamicitat dels fluxos de trĂ fic de xarxes de metro, el qual representa un escenari rellevant de dinamicitat de trĂ fic. Aquesta extensiĂł involucra millores per coordinar els operadors de metro i core amb l’objectiu d’aconseguir una rĂ pida adaptaciĂł de models de trĂ fic OD. Finalment, proposem dues arquitectures de xarxa necessĂ ries per aplicar els mecanismes anteriors en entorns experimentals, emprant protocols estat-de-l’art com sĂłn OpenFlow i IPFIX. La metodologia emprada per avaluar el treball anterior consisteix en una primera avaluaciĂł numèrica fent servir un simulador de xarxes Ăntegrament dissenyat i desenvolupat per a aquesta tesi. DesprĂ©s d’aquesta validaciĂł basada en simulaciĂł, la factibilitat experimental de les arquitectures de xarxa proposades Ă©s avaluada en un entorn de proves distribuĂŻt
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