353 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
Mobility Support in User-Centric Networks
In this paper, an overview of challenges and requirements for mobility management in user-centric networks is given, and a new distributed and dynamic per-application mobility management solution is presented. After a brief summary of generic mobility management concepts, existing approaches from the distributed and peer-to-peer mobility management literature are introduced, along with their applicability or shortcomings in the UCN environment. Possible approaches to deal with the decentralized and highly dynamic nature of UCNs are also provided with a discussion and an introduction to potential future work
Pervasive service discovery in low-power and lossy networks
Pervasive Service Discovery (SD) in Low-power and Lossy Networks (LLNs) is expected to play a major role in realising the Internet of Things (IoT) vision. Such a vision aims to expand the current Internet to interconnect billions of miniature smart objects that sense and act on our surroundings in a way that will revolutionise the future. The pervasiveness and heterogeneity of such low-power devices requires robust, automatic, interoperable and scalable deployment and operability solutions. At the same time, the limitations of such constrained devices impose strict challenges regarding complexity, energy consumption, time-efficiency and mobility.
This research contributes new lightweight solutions to facilitate automatic deployment and operability of LLNs. It mainly tackles the aforementioned challenges through the proposition of novel component-based, automatic and efficient SD solutions that ensure extensibility and adaptability to various LLN environments. Building upon such architecture, a first fully-distributed, hybrid pushpull SD solution dubbed EADP (Extensible Adaptable Discovery Protocol) is proposed based on the well-known Trickle algorithm. Motivated by EADPs’ achievements, new methods to optimise Trickle are introduced. Such methods allow Trickle to encompass a wide range of algorithms and extend its usage to new application domains. One of the new applications is concretized in the TrickleSD protocol aiming to build automatic, reliable, scalable, and time-efficient SD. To optimise the energy efficiency of TrickleSD, two mechanisms improving broadcast communication in LLNs are proposed. Finally, interoperable standards-based SD in the IoT is demonstrated, and methods combining zero-configuration operations with infrastructure-based solutions are proposed.
Experimental evaluations of the above contributions reveal that it is possible to achieve automatic, cost-effective, time-efficient, lightweight, and interoperable SD in LLNs. These achievements open novel perspectives for zero-configuration capabilities in the IoT and promise to bring the ‘things’ to all people everywhere
A Survey on Handover Management in Mobility Architectures
This work presents a comprehensive and structured taxonomy of available
techniques for managing the handover process in mobility architectures.
Representative works from the existing literature have been divided into
appropriate categories, based on their ability to support horizontal handovers,
vertical handovers and multihoming. We describe approaches designed to work on
the current Internet (i.e. IPv4-based networks), as well as those that have
been devised for the "future" Internet (e.g. IPv6-based networks and
extensions). Quantitative measures and qualitative indicators are also
presented and used to evaluate and compare the examined approaches. This
critical review provides some valuable guidelines and suggestions for designing
and developing mobility architectures, including some practical expedients
(e.g. those required in the current Internet environment), aimed to cope with
the presence of NAT/firewalls and to provide support to legacy systems and
several communication protocols working at the application layer
Avaliação de controlo de sessões multicast em redes com contexto
Mestrado em Engenharia Electrónica e TelecomunicaçõesOs utilizadores pretendem aceder, cada vez mais, a serviços multimédia com
requisitos mais exigentes e personalizados. As limitações impostas pelos
ambientes existentes (internet, 3G) para fornecer estes serviços levam à
procura de melhores soluções, nomeadamente uma gestão eficaz das sessões
multiparty. Neste tipo de soluções é normalmente utilizado o multicast, já que
este permite reduzir os recursos utilizados, diminuindo o número de pacotes na
rede. Contudo, o multicast não está consistente ao nível dos cenários de
mobilidade, fundamentais nas redes de próxima geração.
Actualmente existe uma vasta gama de tecnologias de acesso sem fios como
WiFi, GPRS, UMTS e WiMAX. No futuro estas tecnologias diferentes
complementar-se-ão convergindo numa infra-estrutura heterogénea capaz de
fornecer um melhor serviço aos utilizadores, denominadas de redes 4G. A
evolução dos terminais móveis também permitirá que estes se liguem
simultaneamente a várias redes de acesso. Para uma melhor distribuição dos
serviços dos utilizadores pelas redes de acesso disponíveis são necessários
novos mecanismos de selecção. Uma nova selecção da rede baseada em
informação de contexto (entidades e ambiente) tem tido grande relevo na
comunidade científica. Assim, aplicações e rede reagem a alterações de
contexto para uma melhor selecção da mesma.
A dissertação apresentada encontra-se no âmbito do transporte multiparty com
informação de contexto e reserva de recursos, permitindo a entrega do
conteúdo de uma forma personalizada e com Qualidade de Serviço a vários
utilizadores móveis, independentemente da tecnologia de acesso de cada um
e da própria tecnologia da rede. Em suma, é utilizada uma arquitectura de rede
baseada em informação de contexto e que reage eficazmente a alterações do
mesmo.
De forma a implementar a proposta apresentada recorreu-se à criação de
várias entidades no simulador de redes NS-2. Os resultados foram obtidos
usando diferentes cenários, avaliando a influência de cada parâmetro
individualmente. Demonstrou-se que a arquitectura implementada permite
suportar uma entrega dos conteúdos de uma maneira personalizada e
independente da tecnologia utilizada. Obteve-se ainda uma boa gestão dos
recursos da rede e uma melhoria na experiência percepcionada pelo utilizador
através da selecção total da rede com base numa entidade de controlo central.
A introdução do overlay de transporte multiparty melhora o comportamento
geral da rede, minimizando as reconfigurações frequentes necessárias.Nowadays, more and more users want to access multimedia services with
strong and personalized requirements. The limitations intrinsic to current
environments (Internet and 3G) to provide this type of services motivate the
research for an efficient management of multiparty sessions. The solution can
also be based on multicast implementation, since it reduces resources
utilization, decreasing the number of packets in the network. However, current
multicast is not a strong solution in mobility scenarios, essential in next
generation networks.
Currently there is a wide range of wireless access technologies such as WiFi,
GPRS, UMTS and WiMAX. In the future, these different technologies will
converge in a complementary manner forming a heterogeneous infrastructure
able to offer a better service to its users, usually named 4G. The evolution of
mobile terminals will also allow them to connect simultaneously to several
access networks. In order to a better distribution of the users services
throughout available access networks, new selection mechanisms are required.
A new network selection based on context information (entities and
environments) is having a relevant role in scientific community. So, applications
and networks react according to context changes, improving network selection.
This Thesis is in the scope of context-aware multiparty transport with resources
allocation, allowing the delivery of content in a personalized way with Quality of
Service to several users, independently of the technology and the network.
Resuming, the solution implements a context-aware network architecture that
reacts efficiently to its changes.
In order to implement this architecture, new entities were created in the network
simulator NS-2. The results were obtained using different scenarios, evaluating
the influence of each parameter independently. It was demonstrated that the
integration of several components, allows a delivery of contents in a
personalized manner and independently of the technology. The results showed
a better management of the network resources and users experience,
throughout the total network selection, based on a central control unit. The
multiparty transport overlay improves the network behaviour, minimizing the
necessary frequent reconfigurations
Use of locator/identifier separation to improve the future internet routing system
The Internet evolved from its early days of being a small research network to become a critical infrastructure many organizations and individuals rely on. One dimension of this evolution is the continuous growth of the number of participants in the network, far beyond what the initial designers had in mind. While it does work today, it is widely believed that the current design of the global routing system cannot scale to accommodate future challenges.
In 2006 an Internet Architecture Board (IAB) workshop was held to develop a shared understanding of the Internet routing system scalability issues faced by the large backbone operators. The participants documented in RFC 4984 their belief that "routing scalability is the most important problem facing the Internet today and must be solved."
A potential solution to the routing scalability problem is ending the semantic overloading of Internet addresses, by separating node location from identity. Several proposals exist to apply this idea to current Internet addressing, among which the Locator/Identifier Separation Protocol (LISP) is the only one already being shipped in production routers. Separating locators from identifiers results in another level of indirection, and introduces a new problem: how to determine location, when the identity is known.
The first part of our work analyzes existing proposals for systems that map identifiers to locators and proposes an alternative system, within the LISP ecosystem. We created a large-scale Internet topology simulator and used it to compare the performance of three mapping systems: LISP-DHT, LISP+ALT and the proposed LISP-TREE. We analyzed and contrasted their architectural properties as well.
The monitoring projects that supplied Internet routing table growth data over a large timespan inspired us to create LISPmon, a monitoring platform aimed at collecting, storing and presenting data gathered from the LISP pilot network, early in the deployment of the LISP protocol. The project web site and collected data is publicly available and will assist researchers in studying the evolution of the LISP mapping system.
We also document how the newly introduced LISP network elements fit into the current Internet, advantages and disadvantages of different deployment options, and how the proposed transition mechanism scenarios could affect the evolution of the global routing system. This work is currently available as an active Internet Engineering Task Force (IETF) Internet Draft.
The second part looks at the problem of efficient one-to-many communications, assuming a routing system that implements the above mentioned locator/identifier split paradigm. We propose a network layer protocol for efficient live streaming. It is incrementally deployable, with changes required only in the same border routers that should be upgraded to support locator/identifier separation. Our proof-of-concept Linux kernel implementation shows the feasibility of the protocol, and our comparison to popular peer-to-peer live streaming systems indicates important savings in inter-domain traffic.
We believe LISP has considerable potential of getting adopted, and an important aspect of this work is how it might contribute towards a better mapping system design, by showing the weaknesses of current favorites and proposing alternatives. The presented results are an important step forward in addressing the routing scalability problem described in RFC 4984, and improving the delivery of live streaming video over the Internet
Distribuição de vídeo para grupos de utilizadores em redes móveis heterogéneas19
The evolutions veri ed in mobile devices capabilities (storage capacity, screen
resolution, processor, etc.) over the last years led to a signi cant change
in mobile user behavior, with the consumption and creation of multimedia
content becoming more common, in particular video tra c. Consequently,
mobile operator networks, despite being the target of architectural evolutions
and improvements over several parameters (such as capacity, transmission
and reception performance, amongst others), also increasingly become more
frequently challenged by performance aspects associated to the nature of
video tra c, whether by the demanding requirements associated to that
service, or by its volume increase in such networks.
This Thesis proposes modi cations to the mobile architecture towards a more
e cient video broadcasting, de ning and developing mechanisms applicable
to the network, or to the mobile terminal. Particularly, heterogeneous
networks multicast IP mobility supported scenarios are focused, emphasizing
their application over di erent access technologies. The suggested changes
are applicable to mobile or static user scenarios, whether it performs the role
of receiver or source of the video tra c. Similarly, the de ned mechanisms
propose solutions targeting operators with di erent video broadcasting goals,
or whose networks have di erent characteristics. The pursued methodology
combined an experimental evaluation executed over physical testbeds,
with the mathematical evaluation using network simulation, allowing the
veri cation of its impact on the optimization of video reception in mobile
terminalsA evolução veri cada nas características dos dispositivos moveis (capacidade
de armazenamento, resolução do ecrã, processador, etc.) durante os
últimos anos levou a uma alteração signi cativa nos comportamentos dos
utilizadores, sendo agora comum o consumo e produção de conteúdos
multimédia envolvendo terminais móveis, em particular o tráfego vídeo.
Consequentemente, as redes de operador móvel, embora tendo também sido
alvo constante de evoluções arquitecturais e melhorias em vários parâmetros
(tais como capacidade, ritmo de transmissão/recepção, entre outros), vêemse
cada vez mais frequentemente desa adas por aspectos de desempenho
associados à natureza do tráfego de vídeo, seja pela exigência de requisitos
associados a esse serviço, quer pelo aumento do volume do mesmo nesse
tipo de redes.
Esta Tese propôe alterações à arquitetura móvel para a disseminação de vídeo
mais e ciente, de nindo e desenvolvendo mecanismos aplicáveis à rede, ou
ao utilizador móvel. Em particular, são focados cenários suportados por IP
multicast em redes móveis heterogéneas, isto é, com ênfase na aplicação
destes mecanismos sobre diferentes tecnologias de acesso. As alterações
sugeridas aplicam-se a cenários de utilizador estático ou móvel, sendo este a
fonte ou receptor do tráfego vídeo. Da mesma forma, são propostas soluções
tendo em vista operadores com diferentes objectivos de disseminação de
vídeo, ou cujas redes têm diferentes características. A metodologia utilizada
combinou a avaliação experimental em testbeds físicas com a avaliação
matemática em simulações de redes, e permitiu veri car o impacto sobre
a optimização da recepção de vídeo em terminais móveisPrograma Doutoral em Telecomunicaçõe
- …