253 research outputs found
Path signalling in a wireless back-haul network integrating unidirectional broadcast technologies
The black-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, in our previous work, we have developed a cost-effective heterogeneous layer 2.5 wireless back-haul (WiBACK) architecture, which leverages the native multicast capabilities of broadcast technologies such as DVB to off-load high-bandwidth broadcast content delivery. Furthermore, our architecture provides support for unidirectional technologies on the data and the control plane. This adopts a centralized coordinator approach, in which coordinator nodes install so-called management and data pipes. No routing state is kept at plain WiBACK nodes, which merely store QoS-aware pipe forwarding state. Consequently, the architecture requires a reliable protocol to push resource allocation and pipe forwarding state into the network, considering possibly unidirectional connectivity. Such a protocol, whose task is related to MPLS label distribution, is essential during the initial forming of WiBACK topologies and during regular network operations to reliably manage the data pipes. In this paper, we present a novel approach to extend our IEEE 802.21-inspired WiBACK TransportService and, based upon this, the design of an RSVP-TE-style pipe signalling protocol using nested hop-by-hop request/response MIH transactions that supports signalling over unidirectional technologies. A thorough evaluation and successful testbed deployments show that this protocol reliably signals pipe state even under high loss conditions
A Comparative Simulation Study of IP, MPLS, MPLS-TE for Latency and Packet Loss Reduction over a WAN
The need for improved network performance towards providing reliable services in the face of growing demand on enterprise network and internet service across all sectors of the economy has become very paramount. Latency and packet loss as quality of service (QoS) metrics are issues of concern since different multimedia applications, voice and data packets have to be delivered to end systems over long distances. This study investigated the technology behind the delivery of the packets by comparing the performance of each of IP, MPLS and MPLS-TE on the same congested WAN design. The results showed that MPLS-TE had the least latency and barely any packet los
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Integration of unidirectional technologies into wireless back-haul architecture
This thesis was submitted for the degree of Docter of Philosophy and awarded by Brunel University.Back-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, the EU FP7 project CARMEN has developed a cost-effective heterogeneous
multi-radio wireless back-haul architecture, which may also leverage the native multicast
capabilities of broadcast technologies such as DVB-T to off-load high-bandwidth broadcast
content delivery. However, the integration of such unidirectional technologies into a packet-switched architecture requires careful considerations. The contribution of this thesis is the investigation, design and evaluation of protocols and mechanisms facilitating the integration of such unidirectional technologies into the wireless
back-haul architecture so that they can be configured and utilized by the spectrum and
capacity optimization modules. This integration mainly concerns the control plane and, in particular, the aspects related to resource and capability descriptions, neighborhood, link and Multi Protocol Label Switching (MPLS) Label-Switched Path (LSP) monitoring, unicast and multicast LSP signalling as well as topology forming and maintenance. During the course of this study we have analyzed the problem space, proposed solutions to the resulting research questions and evaluated our approach. Our results show that the now Unidirectional Technology (UDT)-aware architecture can readily consider
Unidirectional Technologies (UDTs) to distribute, for example, broadcast content
Revealing and Characterizing MPLS Networks
The Internet is a wide network of computers in constant evolution. Each year, more and more organizations are connected to this worldwide network. Each of them has its own structure and administration that are not publicly revealed for economical, political, and security reasons. Consequently, our perception of the Internet structure, and more specifically, its topology, is incomplete. In order to balance this lack of knowledge, the research community relies on network measurements. Most of the time, they are performed based on the well-known tool traceroute. However, in practice, an operator may privilege other technologies than IP to forward packets inside its network. MultiProtocol Label Switching (MPLS) is one them. Even if it is heavily deployed by operators, it has not been really investigated by researchers. Prior to this thesis, only two studies focused on the identification of MPLS tunnels in traceroute data. Moreover, while one of them does not take all possible scenarios into account, the other lack of precision in some of its models. In addition, MPLS tunnels may hide their content to traceroute. Topologies inferred from such data may thus contain false links or nodes with an artificially high degree, leading so to biases in standard graph metrics used to model the network. Even if some researchers already tried to tackle this issue, the revelation of hidden MPLS devices in traceroute data is still an open question.
This thesis aims at characterizing MPLS in two different ways. On the one hand, at an architectural level, we will analyze in detail its deployment and use in both IPv4 and IPv6 networks in order to improve its state-of-the-art view. We will show that, in practice, more than one IPv4 trace out of two crosses at least one MPLS tunnel. We will also see that, even if this protocol can simplify the internal architecture of transit networks, it also allows some operators to perform traffic engineering in their domain. On the other hand, MPLS will be studied from a measurement point of view. We will see that routers from different manufacturers may have distinct default behaviors regarding to MPLS, and that these specific behaviors can be exploited to identify MPLS tunnels during traceroute measurements. More precisely, we will focus on new methods able to infer the presence of tunnels that are invisible in traceroute outputs, as well as on mechanisms to reveal their content. We will also show that they can be used in order to improve the inference of Internet graph properties, such as path lengths and node degrees. Finally, these techniques will be integrated into Trace the Naughty Tunnels (TNT), a traceroute extension able to identify all types of MPLS tunnels along a path towards a destination. We will prove that this tool can be used in order to get a detailed quantification of MPLS tunnels in the worldwide network. TNT is publicly available, and can therefore be part of many future studies conducted by the research community.Internet est un immense reĢseau informatique en constante eĢvolution. Chaque anneĢe, de plus en plus dāorganisations sāy connectent. Chacune dāelles est geĢreĢe et administreĢe indeĢpendamment des autres. En pratique, lāarchitecture interne de leur reĢseau nāest pas rendue publique pour des raisons politiques, eĢconomiques, ou de seĢcuriteĢ. Par conseĢquent, notre perception de la structure dāInternet, et plus particulieĢrement de sa topologie, est incompleĢte. Afin de pallier ce manque de connaissance, la communauteĢ de la recherche sāappuie sur des mesures de reĢseau. La plupart du temps, elles sont reĢaliseĢes avec lāoutil traceroute. Cependant, des technologies autres que IP peuvent eĢtre privileĢgieĢes pour transfeĢrer les paquets dans un reĢseau. MultiProtocol Label Switching (MPLS) est lāune dāentre elles. MeĢme si cette technologie est largement deĢployeĢe dans Internet, elle nāest pas bien eĢtudieĢe par les chercheurs. Avant cette theĢse, seulement deux travaux se sont inteĢresseĢs aĢ lāidentification dāMPLS dans les donneĢes collecteĢes avec traceroute. Alors que le premier ne prend pas en compte tous les sceĢnarios possibles, le second propose des modeĢles qui manquent de preĢcision. De plus, les tunnels MPLS peuvent dissimuler leur contenu aĢ traceroute. Les topologies infeĢreĢes sur base de ces donneĢes peuvent donc contenir de faux liens, ou des noeuds avec un degreĢ anormalement eĢleveĢ. Les diffeĢrentes modeĢlisations dāInternet qui en reĢsultent peuvent alors eĢtre biaiseĢes. Aujourdāhui, la question de la reĢveĢlation des routeurs MPLS qui sont invisibles dans les donneĢes de mesure nāest toujours pas reĢsolue, meĢme si certains chercheurs ont deĢjaĢ proposeĢ quelques meĢthodes pour y parvenir.
Cette theĢse a pour but de caracteĢriser MPLS de deux manieĢres diffeĢrentes. Dans un premier temps, au niveau architectural, nous analyserons en deĢtail son deĢploiement et son utilisation dans les reĢseaux IPv4 et IPv6 afin dāameĢliorer lāeĢtat de lāart. Nous montrerons quāen pratique, plus dāune trace IPv4 sur deux traverse au moins un tunnel MPLS. Nous deĢcouvrirons eĢgalement que bien que ce protocole peut eĢtre utiliseĢ pour simplifier lāarchitecture interne des reĢseaux de transit, il peut aussi eĢtre deĢployeĢ pour la mise en place de solutions dāingeĢnierie de trafic. Dans un second temps, MPLS sera eĢtudieĢ dāun point de vue mesure. Nous verrons que les comportements par deĢfaut lieĢs au protocole varient dāun fabricant de routeur aĢ lāautre, et quāils peuvent eĢtre exploiteĢs afin dāidentifier les tunnels MPLS dans les donneĢes traceroute. Plus preĢciseĢment, nous deĢcouvrirons de nouvelles meĢthodes capables dāinfeĢrer la preĢsence de tunnels invisibles avec traceroute, ainsi que de nouvelles techniques pour reĢveĢler leur contenu. Nous montrerons eĢgalement quāelles peuvent eĢtre utiliseĢes afin dāameĢliorer la modeĢlisation dāInternet. Pour terminer, ces techniques seront inteĢgreĢes aĢ Trace the Naughty Tunnels (TNT), une extension de traceroute qui permet dāidentifier tous les types de tunnels MPLS le long du chemin vers une destination. Nous prouverons que cet outil peut eĢtre utiliseĢ pour obtenir des statistiques deĢtailleĢes sur le deĢploiement dāMPLS sur Internet. TNT est disponible publiquement, et peut donc eĢtre librement exploiteĢ par la communauteĢ de la recherche pour de multiples futures eĢtudes
Deliverable DJRA1.2. Solutions and protocols proposal for the network control, management and monitoring in a virtualized network context
This deliverable presents several research proposals for the FEDERICA network, in different subjects, such as monitoring, routing, signalling, resource discovery, and isolation. For each topic one or more possible solutions are elaborated, explaining the background, functioning and the implications of the proposed solutions.This deliverable goes further on the research aspects within FEDERICA. First of all the architecture of the control plane for the FEDERICA infrastructure will be defined. Several possibilities could be implemented, using the basic FEDERICA infrastructure as a starting point. The focus on this document is the intra-domain aspects of the control plane and their properties. Also some inter-domain aspects are addressed. The main objective of this deliverable is to lay great stress on creating and implementing the prototype/tool for the FEDERICA slice-oriented control system using the appropriate framework. This deliverable goes deeply into the definition of the containers between entities and their syntax, preparing this tool for the future implementation of any kind of algorithm related to the control plane, for both to apply UPB policies or to configure it by hand. We opt for an open solution despite the real time limitations that we could have (for instance, opening web services connexions or applying fast recovering mechanisms). The application being developed is the central element in the control plane, and additional features must be added to this application. This control plane, from the functionality point of view, is composed by several procedures that provide a reliable application and that include some mechanisms or algorithms to be able to discover and assign resources to the user. To achieve this, several topics must be researched in order to propose new protocols for the virtual infrastructure. The topics and necessary features covered in this document include resource discovery, resource allocation, signalling, routing, isolation and monitoring. All these topics must be researched in order to find a good solution for the FEDERICA network. Some of these algorithms have started to be analyzed and will be expanded in the next deliverable. Current standardization and existing solutions have been investigated in order to find a good solution for FEDERICA. Resource discovery is an important issue within the FEDERICA network, as manual resource discovery is no option, due to scalability requirement. Furthermore, no standardization exists, so knowledge must be obtained from related work. Ideally, the proposed solutions for these topics should not only be adequate specifically for this infrastructure, but could also be applied to other virtualized networks.Postprint (published version
System architecture and hardware implementations for a reconfigurable MPLS router
With extremely wide bandwidth and good channel properties, optical fibers have brought fast and reliable data transmission to todayās data communications. However, to handle heavy traffic flowing through optical physical links, much faster processing speed is required or else congestion can take place at network nodes. Also, to provide people with voice, data and all categories of multimedia services, distinguishing between different data flows is a requirement. To address these router performance, Quality of Service /Class of Service and traffic engineering issues, Multi-Protocol Label Switching (MPLS) was proposed for IP-based Internetworks. In addition, routers flexible in hardware architecture in order to support ever-evolving protocols and services without causing big infrastructure modification or replacement are also desirable. Therefore, reconfigurable hardware implementation of MPLS was proposed in this project to obtain the overall fast processing speed at network nodes.
The long-term goal of this project is to develop a reconfigurable MPLS router, which uniquely integrates the best features of operations being conducted in software and in run-time-reconfigurable hardware. The scope of this thesis includes system architecture and service algorithm considerations, Verilog coding and testing for an actual device. The hardware and software co-design technique was used to partition and schedule the protocol code for execution on both a general-purpose processor and stream-based hardware. A novel RPS scheme that is practically easy to build and can realize pipelined packet-by-packet data transfer at each output was proposed to take the place of the traditional crossbar switching. In RPS, packets with variable lengths can be switched intelligently without performing packet segmentation and reassembly. Primary theoretical analysis of queuing issues was discussed and an improved multiple queue service scheduling policy UD-WRR was proposed, which can reduce packet-waiting time without sacrificing the performance. In order to have the tests carried out appropriately, dedicated circuitry for the MPLS functional block to interface a specific MAC chip was implemented as well. The hardware designs for all functions were realized with a single Field Programmable Gate Array (FPGA) device in this project.
The main result presented in this thesis was the MPLS function implementation realizing a major part of layer three routing at the reconfigurable hardware level, which advanced a great step towards the goal of building a router that is both fast and flexible
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