687 research outputs found
A Survey of Quality of Service Differentiation Mechanisms for Optical Burst Switching Networks
Cataloged from PDF version of article.This paper presents an overview of Quality of Service (QoS) differentiation mechanisms
proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple
the benefits of both circuit and packet switching for the ‘‘on demand’’ use of capacity in
the future optical Internet. In such a case, QoS support imposes some important challenges
before this technology is deployed. This paper takes a broader view on QoS, including QoS
differentiation not only at the burst but also at the transport levels for OBS networks.
A classification of existing QoS differentiation mechanisms for OBS is given and their
efficiency and complexity are comparatively discussed. We provide numerical examples
on how QoS differentiation with respect to burst loss rate and transport layer throughput
can be achieved in OBS networks.
© 2009 Elsevier B.V. All rights reserved
Burst switched optical networks supporting legacy and future service types
Focusing on the principles and the paradigm of OBS an overview addressing expectable performance and application issues is presented. Proposals on OBS were published over a decade and the presented techniques spread into many directions. The paper comprises discussions of several challenges that OBS meets, in order to compile the big picture. The OBS principle is presented unrestricted to individual proposals and trends. Merits are openly discussed, considering basic teletraffic theory and common traffic characterisation. A more generic OBS paradigm than usual is impartially discussed and found capable to overcome shortcomings of recent proposals. In conclusion, an OBS that offers different connection types may support most client demands within a sole optical network layer
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Survey of traffic control schemes and error control schemes for ATM networks
Among the techniques proposed for B-ISDN transfer mode, ATM concept is considered to be the most promising transfer technique because of its flexibility and efficiency. This paper surveys and reviews a number of topics related to ATM networks. Those topics cover congestion control, provision of multiple classes of traffic, and error control. Due to the nature of ATM networks, those issues are far more challenging than in conventional networks. Sorne of the more promising solutions to those issues are surveyed, and the corresponding results on performance are summarized. Future research problems in ATM protocol aspect are also presented
Architectures and protocols for sub-wavelength optical networks: contributions to connectionless and connection-oriented data transport
La rà pida evolució d’Internet i l’à mplia gamma de noves aplicacions (per exemple, multimèdia, videoconferència, jocs en lÃnia, etc.) ha fomentat canvis revolucionaris en la manera com ens comuniquem. A més, algunes d’aquestes aplicacions demanden grans quantitats de recursos d’ample de banda amb diversos requeriments de qualitat de servei (QoS).
El desenvolupament de la multiplexació per divisió de longitud d’ona (WDM) en els anys noranta va fer molt rendible la disponibilitat d’ample de banda. Avui dia, les tecnologies de commutació òptica de circuits són predominants en el nucli de la xarxa, les quals permeten la configuració de canals (lightpaths) a través de la xarxa. No obstant això, la granularitat d’aquests canals ocupa tota la longitud d’ona, el que fa que siguin ineficients per a proveir canals de menor ample de banda (sub-longitud d’ona). Segons la comunitat cientÃfica, és necessari augmentar la transparència dels protocols, aixà com millorar l’aprovisionament d’ample de banda de forma dinà mica. Per tal de fer això realitat, és necessari desenvolupar noves arquitectures. La commutació òptica de rà fegues i de paquets (OBS/OPS), són dues de les tecnologies proposades.
Aquesta tesi contribueix amb tres arquitectures de xarxa destinades a millorar el transport de dades sub-longitud d’ona. En primer lloc, aprofundim en la naturalesa sense connexió en OBS. En aquest cas, la xarxa incrementa el seu dinamisme a causa de les transmissions a rà fega. A més, les col·lisions entre rà fegues degraden el rendiment de la xarxa fins i tot a cà rregues molt baixes. Per fer front a aquestes col·lisions, es proposa un esquema de resolució de col·lisions pro actiu basat en un algorisme d’encaminament i assignació de longitud d’ona (RWA) que balanceja de forma automà tica i distribuïda la cà rrega en la xarxa. En aquest protocol, el RWA i la transmissió de rà fegues es basen en l’explotació i exploració de regles de commutació que incorporen informació sobre contencions i encaminament. Per donar suport a aquesta arquitectura, s’utilitzen dos tipus de paquets de control per a l’encaminament de les rà fegues i l’actualització de les regles de commutació, respectivament. Per analitzar els beneficis del nou algorisme, s’utilitzen quatre topologies de xarxa diferents. Els resultats indiquen que el mètode proposat millora en diferents marges la resta d’algorismes RWA en funció de la topologia i sense penalitzar altres parà metres com el retard extrem a extrem.
La segona contribució proposa una arquitectura hÃbrida sense i orientada a connexió sobre la base d’un protocol de control d’accés al medi (MAC) per a xarxes OBS (DAOBS). El MAC ofereix dos mètodes d’accés: arbitratge de cua (QA) per a la transmissió de rà fegues sense connexió, i pre-arbitratge (PA) per serveis TDM orientats a connexió. Aquesta arquitectura permet una à mplia gamma d’aplicacions sensibles al retard i al bloqueig. Els resultats avaluats a través de simulacions mostren que en l’accés QA, les rà fegues de més alta prioritat tenen garantides zero pèrdues i latències d’accés molt baixes. Pel que fa a l’accés PA, es reporta que la duplicació de la cà rrega TDM augmenta en més d’un ordre la probabilitat de bloqueig, però sense afectar en la mateixa mesura les rà fegues sense connexió. En aquest capÃtol també es tracten dos dels problemes relacionats amb l’arquitectura DAOBS i el seu funcionament. En primer lloc, es proposa un model matemà tic per aproximar el retard d’accés inferior i superior com a conseqüència de l’accés QA. En segon lloc, es formula matemà ticament la generació i optimització de les topologies virtuals que suporten el protocol per a l’escenari amb trà fic està tic.
Finalment, l’última contribució explora els beneficis d’una arquitectura de xarxa òptica per temps compartit (TSON) basada en elements de cà lcul de camins (PCE) centralitzats per tal d’evitar col·lisions en la xarxa. Aquesta arquitectura permet garantir l’aprovisionament orientat a connexió de canals sub-longitud d’ona. En aquest capÃtol proposem i simulem tres arquitectures GMPLS/PCE/TSON. A causa del enfocament centralitzat, el rendiment de la xarxa depèn en gran mesura de l’assignació i aprovisionament de les connexions. Amb aquesta finalitat, es proposen diferents algorismes d’assignació de ranures temporals i es comparen amb les corresponents formulacions de programació lineal (ILP) per al cas està tic. Per al cas de trà fic dinà mic, proposem i avaluem mitjançant simulació diferents heurÃstiques. Els resultats mostren els beneficis de proporcionar flexibilitat en els dominis temporal i freqüencial a l’hora d’assignar les ranures temporals.The rapid evolving Internet and the broad range of new data applications (e.g., multimedia, video-conference, online gaming, etc.)
is fostering revolutionary changes in the way we communicate. In addition, some of these applications demand for unprecedented
amounts of bandwidth resources with diverse quality of service (QoS).
The development of wavelength division multiplexing (WDM) in the 90's made very cost-effective the availability of bandwidth.
Nowadays, optical circuit switching technologies are predominant in the core enabling the set up of lightpaths across the network.
However, full-wavelength lightpath granularity is too coarse, which results to be inefficient for provisioning sub-wavelength
channels. As remarked by the research community, an open issue in optical networking is increasing the protocol transparency as
well as provisioning true dynamic bandwidth allocation at the network level. To this end, new architectures are required. Optical
burst/packet switching (OBS/OPS) are two such proposed technologies under investigation.
This thesis contributes with three network architectures which aim at improving the sub-wavelength data transport from different
perspectives. First, we gain insight into the connectionless nature of OBS. Here, the network dynamics are increased due to the
short-lived burst transmissions. Moreover, burst contentions degrade the performance even at very low loads. To cope with them,
we propose a proactive resolution scheme by means of a distributed auto load-balancing routing and wavelength assignment
(RWA) algorithm for wavelength-continuity constraint networks. In this protocol, the RWA and burst forwarding is based on the
exploitation and exploration of switching rule concentration values that incorporate contention and forwarding desirability
information. To support such architecture, forward and backward control packets are used in the burst forwarding and updating
rules, respectively. In order to analyze the benefits of the new algorithm, four different network topologies are used. Results
indicate that the proposed method outperforms the rest of tested RWA algorithms at various margins depending on the topology
without penalizing other parameters such as end-to-end delay.
The second contribution proposes a hybrid connectionless and connection-oriented architecture based on a medium access control
(MAC) protocol for OBS networks (DAOBS). The MAC provides two main access mechanisms: queue arbitrated (QA) for
connectionless bursts and pre-arbitrated (PA) for TDM connection-oriented services. Such an architecture allows for a broad range
of delay-sensitive applications or guaranteed services. Results evaluated through simulations show that in the QA access mode
highest priority bursts are guaranteed zero losses and very low access latencies. Regarding the PA mode, we report that doubling
the offered TDM traffic load increases in more than one order their connection blocking, slightly affecting the blocking of other
connectionless bursts. In this chapter, we also tackle two of the issues related with the DAOBS architecture and its operation.
Firstly, we model mathematically the lower and upper approximations of the access delay as a consequence of the connectionless
queue arbitrated access. Secondly, we formulate the generation of the virtual light-tree overlay topology for the static traffic case.Postprint (published version
Performance issues in optical burst/packet switching
The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-01524-3_8This chapter summarises the activities on optical packet switching (OPS) and optical burst switching (OBS) carried out by the COST 291 partners in the last 4 years. It consists of an introduction, five sections with contributions on five different specific topics, and a final section dedicated to the conclusions. Each section contains an introductive state-of-the-art description of the specific topic and at least one contribution on that topic. The conclusions give some points on the current situation of the OPS/OBS paradigms
GMPLS-OBS interoperability and routing acalability in internet
The popularization of Internet has turned the telecom world upside down over the last two decades. Network operators, vendors and service providers are being challenged to adapt themselves to Internet requirements in a way to properly serve the huge number of demanding users (residential and business). The Internet (data-oriented network) is supported by an IP packet-switched architecture on top of a circuit-switched, optical-based architecture (voice-oriented network), which results in a complex and rather costly infrastructure to the transport of IP traffic (the dominant traffic nowadays). In such a way, a simple and IP-adapted network architecture is desired.
From the transport network perspective, both Generalized Multi-Protocol Label Switching (GMPLS) and Optical Burst Switching (OBS) technologies are part of the set of solutions to progress towards an IP-over-WDM architecture, providing intelligence in the control and management of resources (i.e. GMPLS) as well as a good network resource access and usage (i.e. OBS). The GMPLS framework is the key enabler to orchestrate a unified optical network control and thus reduce network operational expenses (OPEX), while increasing operator's revenues. Simultaneously, the OBS technology is one of the well positioned switching technologies to realize the envisioned IP-over-WDM network architecture, leveraging on the statistical multiplexing of data plane resources to enable sub-wavelength in optical networks. Despite of the GMPLS principle of unified control, little effort has been put on extending it to incorporate the OBS technology and many open questions still remain.
From the IP network perspective, the Internet is facing scalability issues as enormous quantities of service instances and devices must be managed. Nowadays, it is believed that the current Internet features and mechanisms cannot cope with the size and dynamics of the Future Internet. Compact Routing is one of the main breakthrough paradigms on the design of a routing system scalable with the Future Internet requirements. It intends to address the fundamental limits of current stretch-1 shortest-path routing in terms of RT scalability (aiming at sub-linear growth). Although "static" compact routing works fine, scaling logarithmically on the number of nodes even in scale-free graphs such as Internet, it does not handle dynamic graphs. Moreover, as multimedia content/services proliferate, the multicast is again under the spotlight as bandwidth efficiency and low RT sizes are desired. However, it makes the problem even worse as more routing entries should be maintained.
In a nutshell, the main objective of this thesis in to contribute with fully detailed solutions dealing both with i) GMPLS-OBS control interoperability (Part I), fostering unified control over multiple switching domains and reduce redundancy in IP transport. The proposed solution overcomes every interoperability technology-specific issue as well as it offers (absolute) QoS guarantees overcoming OBS performance issues by making use of the GMPLS traffic-engineering (TE) features. Keys extensions to the GMPLS protocol standards are equally approached; and ii) new compact routing scheme for multicast scenarios, in order to overcome the Future Internet inter-domain routing system scalability problem (Part II). In such a way, the first known name-independent (i.e. topology unaware) compact multicast routing algorithm is proposed. On the other hand, the AnyTraffic Labeled concept is also introduced saving on forwarding entries by sharing a single forwarding entry to unicast and multicast traffic type. Exhaustive simulation campaigns are run in both cases in order to assess the reliability and feasible of the proposals
A survey of quality of service differentiation mechanisms for optical burst switching networks
This paper presents an overview of Quality of Service (QoS) differentiation mechanisms proposed for Optical Burst Switching (OBS) networks. OBS has been proposed to couple the benefits of both circuit and packet switching for the "on demand" use of capacity in the future optical Internet. In such a case, QoS support imposes some important challenges before this technology is deployed. This paper takes a broader view on QoS, including QoS differentiation not only at the burst but also at the transport levels for OBS networks. A classification of existing QoS differentiation mechanisms for OBS is given and their efficiency and complexity are comparatively discussed. We provide numerical examples on how QoS differentiation with respect to burst loss rate and transport layer throughput can be achieved in OBS networks. © 2009 Elsevier B.V. All rights reserved
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