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  • Experimental assessment of bulk path restoration in multi-layer networks using PCE-based global concurrent optimization

     Castro Casales, Alberto; Martínez, Ricardo; Casellas Regi, Ramón; Velasco Esteban, Luis; Muñoz González, Raul; Vilalta, Ricard; Comellas Colome, Jaume
    Journal of lightwave technology
    Vol. 32, num. 1, p. 81-90
    DOI: 10.1109/JLT.2013.2290588
    Date of publication: 2014-01-01
    Journal article

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    GMPLS-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN TE strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet LSPs. Thereby, efficient recovery schemes such as restoration are required. In dynamic restoration, the centralized Path Computation Element (PCE) sequentially computes backup paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE Global Concurrent Optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as Bulk pAth REstoration in Multi-layer Optical networks (BAREMO), is formally modeled and stated using a MILP formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the restoration time.

    Generalized multi-protocol label switching-based multi-layer networks (MLN) combining packet and optical switching lead to jointly leverage intrinsic per-layer benefits such as statistical multiplexing and huge transport capacity. By doing so, efficient network resource utilization is attained through MLN traffic engineering (TE) strategies, i.e. grooming. In this context, an optical link failure may cause the disruption of multiple groomed packet label switched paths (LSPs). Thereby, efficient recovery schemes such as restoration are required. In dynamic restoration, the centralized path computation element (PCE) sequentially computes backup paths for the set of failed packet LSPs using the TE database (TED). Since the TED is not updated until an LSP is actually set up, it is very likely that the PCE assigns the same network resources to different backup paths. This does increase resource contention and not fully exploits the potential grooming opportunities among the backup LSPs; consequently, the restorability metric performs poorly. To improve this, a designed PCE global concurrent optimization (GCO) architecture is implemented favoring grooming and lowering resource contention. The addressed problem, referred to as bulk path restoration in multi-layer optical networks (BAREMO), is formally modeled and stated using a mixed integer linear programming formulation. Then, a heuristic algorithm solving the BAREMO problem is devised. The experimental performance evaluation is conducted within the ADRENALINE testbed. Besides validating the PCE GCO architecture, its performance is compared with a sequential PCE for several traffic loads and failure rates. The results show that the PCE GCO improves remarkably restorability compared to the sequential PCE at the expenses, however, of increasing the restoration time.

  • Optimal route, spectrum, and modulation level assignment in split-spectrum-enabled dynamic elastic optical networks

     Pages Cruz, Albert; Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume
    Journal of optical communications and networking
    Vol. 6, num. 2, p. 114-126
    DOI: 10.1364/JOCN.6.000114
    Date of publication: 2014-02-01
    Journal article

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    The spectrum fragmentation effect in elastic optical networks is one of their main limitations. Multiple techniques have been proposed to address this problem, with the split spectrum approach (SSA) being a very interesting candidate among them. This technique is based on splitting a demand into smaller sub-demands when a blocking situation arises. In split-spectrum-enabled networks, the route, spectrum, and modulation level assignment (RSMLA) problem that appears in elastic optical networks is further complicated due to the signal splitting operation. In this paper we present novel mechanisms to optimally attack this problem; various possible implementations of the SSA are also discussed. We highlight the benefits of the proposed mechanisms through illustrative results and compare the various implementation solutions in terms of average network cost.

  • Dynamic Routing and Spectrum Allocation in Elastic Optical Networks  Open access

     Sayyad Khodashenas, Pouria
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Degut a l¿augment de serveis emergent com la distribució de vídeo d¿alta definició o les xarxes socials, el volum de tràfic IP ha crescut de manera exponencial durant els darrers temps. La conseqüència esperable és que els operadors de xarxes de telecomunicacions requeriran una nova generació de transport òptic en el futur proper, per donar servei a aquests grans i heterogenis volums de tràfic d¿una manera econòmicament eficient i escalable. Com a resposta a les creixents necessitats de capacitat i de diferents granularitats de tràfic de la Internet del Futur s¿ha proposat l¿arquitectura coneguda com ¿Elastic Optical Network¿ (EON) on s¿aconsegueix incrementar la flexibilitat en l¿aprovisionament de connexions. Per fer-ho, depenent del volum de tràfic s¿assigna la quantitat adient de l¿espectre òptic a cada connexió. D¿aquesta manera, les peticions de connexió que arriben poden ésser servides de manera eficient pel que fa a l¿espectre que utilitzen. Aquest avenç tecnològic implica però alguns reptes a nivell de xarxa, especialment pel que fa a l¿establiment eficient de les connexions. El problema de l¿encaminament i assignació de l¿espectre (RSA) ha merescut una gran atenció dels investigadors en els darrers anys, amb especial èmfasi a escenaris dinàmics, és a dir, en la fase d¿operació de la xarxa. En aquest cas, els processos d¿arribada i mort de les connexions són aleatoris i la xarxa ha d¿acomodar en temps real el tràfic ofert. Tot i els grans esforços dedicats a aquest tema, queden encara alguns punts a resoldre. Aquesta Tesi està dedicada a alguns d¿aquests temes oberts en l¿àmbit de les xarxes EON: 1) l¿agregació dinàmica de connexions de granularitat inferior a la longitud d¿ona, 2) la correlació entre la granularitat del tràfic i les polítiques de desfragmentació de l¿espectre, i, 3) utilitzar la fragmentació espectral per a una millor assignació de connexions d¿ample de banda canviant en el temps. El primer analitza la possibilitat d¿agregar connexions originades a la mateixa font però amb diferents destinacions dins d¿una EON, amb l¿objectiu d¿estalviar recursos tant pel que fa a nombre d¿equips transmissor utilitzats com a l¿espectre utilitzat. S¿ha proposat un nou algorisme que millora ambdós paràmetres, així com una arquitectura pels nodes de la xarxa que permet utilitzar l¿algorisme d¿agregació proposat de manera eficient des del punt de vista del cost. El problema de la fragmentació espectral en les EONs s¿ataca en la segona aportació d¿aquesta Tesi. S¿ha aconseguit demostrar la correlació entre l¿òptima (és a dir mínima) periodicitat de les accions de desfragmentació i la granularitat del tràfic suportat. S¿ha proposat un nou algorisme per a una desfragmentació eficient, l¿objectiu del qual és consolidar l¿espectre disponible en les fibres tan com sigui possible, al mateix temps que es redueix el nombre de connexions que has de ser reubicades en la xarxa. Finalment, en el tercer gran apartat de la Tesi, s¿estudia la possibilitat d¿utilitzar la fragmentació espectral en les EON per a una millor assignació dels recursos quan el tràfic és variant en el temps. En aquest context, s¿ha proposat i validat un algorisme d¿assignació de l¿espectre (SA) que incrementa de manera intencionada la fragmentació espectral de la xarxa. En aquesta proposta, l¿espectre assignat a cada nova connexió s¿ubica al bell mig del buit espectral més gran que es troba en tota la ruta, amb l¿objectiu de deixar tan espai com sigui possible entre les diferents connexions. Aquest espai és després utilitzat per a connexions que requereixen, al llarg de la seva existència, més espectre del que se¿ls ha assignat inicialment (incrementen el seu ample de banda).

    Triggered by emerging services such as high-definition video distribution or social networking, the IP traffic volume has been exponentially increasing to date. Furthermore, the traffic growth rate will not stop here due to the day by day technology advances. For example, new hardware advances such as multicore processing, virtualization and network storage will support new generation e-Science and grid applications, requesting data flows of 10 Gb/s up to terabit level. In response to these large capacity and diverse traffic granularity needs of the future Internet, the Elastic Optical Network (EON) architecture has been proposed. By breaking the fixed-grid spectrum allocation limit of conventional Wavelength Division Multiplexing (WDM) networks, EONs increase the flexibility in the connection provisioning. To do so, depending on the traffic volume, an appropriate-sized optical spectrum is allocated to a connection in EONs. Furthermore, unlike the rigid optical channels of conventional WDM networks, a lightpath can expand or contract elastically to meet different bandwidth demands in EONs. In this way, incoming connection requests can be served in a spectrum-efficient manner. This technological advance poses additional challenges on the networking level, specifically on the efficient connection establishment. The Routing and Spectrum Allocation (RSA) problem in elastic optical networks has grabbed a lot of attention lately, putting more emphasis on dynamic network scenarios. There, connection arrival and departure processes are random and the network has to accommodate incoming traffic in real time. Despite all efforts at studying the dynamic RSA problem from different perspectives, there are still some issues which need to be addressed. This thesis is devoted to the study of three still open issues in the EONs literature, 1) dynamic source aggregation of sub-wavelength connections, 2) correlation between traffic granularity and defragmentation periodicity and 3) using spectrum fragmentation to better allocate time-varying connections. The first issue deals with the possibility of aggregation of same source but different destination sub-wavelength connections in EONs, aiming to obtain both transmitter and spectrum usage savings. A novel algorithm for dynamic source aggregation of connections is proposed. Moreover, a novel node architecture enabling the realization of the proposed source aggregation scheme in a cost-effective way is introduced. A considerable improvement in the network spectrum utilization, as well as a significant reduction in the number of necessary transmitters per node is shown. The spectral fragmentation problem in elastic optical networks is addressed with the second issue. A correlation between the optimal (i.e., minimum) spectrum defragmentation periodicity in the network with the granularity of the supported traffic is investigated. A novel algorithm for efficient spectrum defragmentation is proposed, aiming to consolidate the available fiber spectrum as much as possible, while limiting the number of re-allocated active connections. It is shown that the spectral defragmentation periodicity can be effectively configured by having knowledge of the offered traffic granularity. The last issue is about lightpath adaptation under time variable traffic demands in EONs. Specifically, the possibility of utilizing the spectral fragmentation to increase the spectrum allocation capabilities of EONs is explored. In this context, a heuristic Spectrum Allocation (SA) algorithm, which intentionally increases the spectral fragmentation in the network is proposed and validated. In the proposal, the spectrum assigned to each new connection is in the middle of the largest free spectral void over the route, aiming to provide considerable spectral space between adjacent connections. These free spectral spaces are then used to allocate time-varying connections without requiring any lightpath re-allocation.

    Degut a l'augment de serveis emergent com la distribució de vídeo d'alta definició les xarxes socials, el volum de tràfic IP ha crescut de manera exponencial durant els darrers temps. S'espera que aquest creixement no s'aturi sinó que continui de manera imparable degut als constants avenços tecnològics. Alguns exemples d’això poden ser els processadors multi-nucli, la virtualització o el "cloud computing" que donaran suport a una nova generació de e-Science i d'aplicacions Grid per les quals caldran flux de dades des de 10 Gb/s fins al Terabit per segon. La conseqüència esperable és que els operadors de xarxes de telecomunicacions requeriran una nova generació de transport òptic en el futur proper, per donar servei a aquests grans i heterogenis volums de trafic d'una manera econòmicament eficient i escalable. Com a resposta a les creixents necessitats de capacitat i de diferents granularitats de tràfic de la Internet del Futur s'ha proposat l'arquitectura coneguda com "Elastic Optical Network" (EON). Trencant el rígid entramat de les xarxes WDM tradicionals, on s'ha de reservar tot un canal òptic per a cada comunicació, mitjançant les EON s'aconsegueix incrementar la flexibilitat en l'aprovisionament de connexions. per fer-ho, depenent del volum de tràfic s'assigna la quantitat adient de l'espectre òptic a cada connexió. I, anant encara un pas més enllà, per desfer la rigidesa dels canals convencionals de les xarxes amb multiplexació per divisió en longitud d'ona (WDM), les connexions òptiques en les EON poden expandir-se o contraure's de manera elàstica segons els requeriments d'ample de banda en cada moment. D'aquesta manera, les peticions de connexió que arriben poden ésser servides de manera eficient pel que fa a l'espectre que utilitzen. Aquest avenç tecnològic implica però alguns reptes a nivell de xarxa, especialment pel que fa a l'establiment eficient de les connexions. De manera similar a com succeeix en les xarxes WDM, una connexió ha d'ocupar la mateixa part de l'espectre en tots els links que la conformen, acomplint el principi de "continuïtat en l'espectre". A més a més, tot l'ample de banda de la connexió ha d'estar assignat de manera adjacent, acomplint el principi de "contigüitat en l'espectre". Per aconseguir aquests objectius, el problema de l'encaminament i assignació de l'espectre (RSA) ha merescut una gran atenció dels investigadors en els darrers anys, amb especial èmfasi a escenaris dinàmics, és a dir, en la fase d’operació de la xarxa. En aquest cas, els processos d'arribada i mort de les connexions són aleatoris i la xarxa ha d'acomodar en temps real el tràfic ofert. Tot i els grans esforços dedicats a aquest tema, queden encara alguns punts a resoldre. Aquesta Tesi està dedicada a alguns d'aquests temes oberts en l'àmbit de les xarxes EON: 1) l’agregació dinàmica de connexions de granularitat inferior a la longitud d'ona, 2) la correlació entre la granularitat del tràfic i les polítiques de desfragmentació de l'espectre, i, 3) utilitzar la fragmentació espectral per a una millor assignació de connexions d'ample de banda canviant en el temps. El primer tòpic analitza la possibilitat d'agregar connexions originades a la mateixa font però amb diferents destinacions dins d'una EON, amb l'objectiu d'estalviar recursos tant pel que fa a nombre d'equips transmissor utilitzats com a l'espectre utilitzat. S'ha proposat un nou algorisme que millora ambdós paràmetres, així com una arquitectura pels nodes de la xarxa que permet utilitzar l'algorisme d’agregació proposat de manera eficient des del punt de vista del cost. S'aconsegueix una considerable millora pel que fa a la utilització de l'espectre a més d'una significativa reducció en el nombre de transmissors per node que es requereixen. El problema de la fragmentació espectral en les EONs s'ataca en la segona aportació d'aquesta Tesi. S'ha aconseguit demostrar la correlació entre l’òptima (és a dir mínima) periodicitat de les accions de desfragmentació i la granularitat del tràfic suportat. S'ha proposat un nou algorisme per a una desfragmentació eficient, l'objectiu del qual és consolidar l'espectre disponible en les fibres tan com sigui possible, al mateix temps que es redueix el nombre de connexions que has de ser reubicades en la xarxa. Es demostra que, en una EON, es pot configurar de manera òptima la periodicitat de les desfragmentacions si es coneix la granularitat de les connexions a transportar. Finalment, en el tercer gran apartat de la Tesi, s'estudia la possibilitat d'utilitzar la fragmentació espectral en les EON per a una millor assignació dels recursos quan el tràfic és variant en el temps. En aquest context, s'ha proposat i validat un algorisme d’assignació de l'espectre (SA) que incrementa de manera intencionada la fragmentació espectral de la xarxa. En aquesta proposta, l'espectre assignat a cada nova connexi_o s'ubica al bell mig del buit espectral més gran que es troba en tota la ruta, amb l'objectiu de deixar tan espai com sigui possible entre les diferents connexions. Aquest espai és després utilitzat per a connexions que requereixen, al llarg de la seva existència, més espectre del que se'ls ha assignat inicialment (incrementen el seu ample de banda). Els resultats obtinguts mitjançant simulacions mostren significants millores en termes de Probabilitat de Bloqueig (BP) en la xarxa quan s'utilitza l'algorisme proposat. Després d'una introducció a la Tesi, el Capítol 2 ofereix una revisió de l’evolució de les xarxes òptiques de transport, tot introduint el concepte de xarxa òptica elàstica (EON). El Capítol 3 se centra en l'estudi dels mètodes d'encaminament i assignació de longitud d'ona en xarxes WDM convencionals, i la seva evolució cap al problema de l’assignació d'espectre (RSA) en EONs. El Capítol 4 detalla els estudis i les contribucions fetes en el tema d’agregació de connexions de granularitat inferior a la longitud d'ona en EONs. L'algorisme proposat, així com l'arquitectura de node que permet aplicar-lo es presenten en aquest Capítol. El problema de la fragmentació espectral en EONs i llurs solucions es revisen a fons en el Capítol 5. La correlació entre la periodicitat de les desfragmentacions espectrals i la granularitat del tràfic ofert s'estudien aquí. El Capítol 6 detalla el problema de servir connexions variants en el temps en EONs. Algunes polítiques proposades fins ara es revisen, i tot seguit se'n proposa una que, en certs aspectes, millora les prèvies. Finalment, cal destacar que aquest treball ha rebut el suport del Govern de la Generalitat de Catalunya, a través d'una beca FI-AGAUR, i que s'ha realitzat en el marc del projecte del Ministerio de Educación Ciencia y Deporte espanyol ELASTIC (TEC2011-27310).

    Debido al aumento de servicios emergentes como la distribución de video de alta definición o las redes sociales, el volumen de tráfico IP ha crecido de manera exponencial durante los últimos tiempos. Se espera que este crecimiento no se pare sino que continúe de manera imparable debido a los constantes adelantos tecnológicos. Algunos ejemplos de esto pueden ser los procesadores multi-núcleo, la virtualización o el "cloud computing" que darán servicio a una nueva generación de aplicaciones de e-Science y de Grid para las cuáles serán necesarios flujos de datos desde 10 Gb/s hasta Terabits por segundo. La consecuencia esperable es que los operadores de redes de telecomunicaciones requerirán una nueva generación de transporte óptico en el futuro cercano, para dar servicio a estos grandes y heterogéneos volúmenes de tráfico de una manera económicamente eficiente y escalable. Como respuesta a las crecientes necesidades de capacidad y de diferentes granularidades de tráfico de la Internet del Futuro, se ha propuesto la arquitectura conocida como "Elastic Optical Network" (EON). Rompiendo el rígido entramado de las redes con multiplexación por división en longitud de onda (WDM) tradicionales, donde se tiene que reservar todo un canal óptico para cada comunicación, mediante las EON se consigue incrementar la flexibilidad en el aprovisionamiento de conexiones. Para hacerlo, dependiendo del volumen de tráfico se asigna la cantidad adecuada del espectro óptico a cada conexión. Y, yendo todavía un paso más allá, para deshacer la rigidez de los canales convencionales de las redes WDM, las conexiones ópticas en las EON pueden expandirse o contraerse de manera elástica según los requerimientos de ancho de banda en cada momento. De este modo, las peticiones de conexión que llegan pueden ser servidas de manera eficiente en cuanto al espectro que utilizan. Este adelanto tecnológico implica sin embargo algunos retos a nivel de red, especialmente en lo que se refiere al establecimiento eficiente de las conexiones. De manera similar a como sucede en las redes WDM, una conexión debe ocupar la misma parte del espectro en todos los links que la conforman, cumpliendo el principio de "continuidad espectral". Además, todo el ancho de banda de la conexión tiene que estar asignado de manera adyacente, cumpliendo el principio de "contigüidad espectral". Para conseguir estos objetivos, el problema del encaminamiento y asignación del espectro (RSA) ha merecido una gran atención de los investigadores en los últimos años, con especial énfasis en escenarios dinámicos, es decir, en la fase de operación de la red. En este caso, los procesos de llegada y finalización de las conexiones son aleatorios y la red tiene que acomodar en tiempo real el tráfico ofrecido. A pesar de los grandes esfuerzos dedicados a este tema, quedan todavía algunos puntos a resolver. Esta Tesis está dedicada a algunos de estos temas abiertos en el ámbito de las redes EON: 1) la agregación dinámica de conexiones de granularidad inferior a la longitud de onda, 2) la correlación entre la granularidad del tráfico y las políticas de desfragmentación del espectro, y, 3) utilizar la fragmentación espectral para una mejor asignación de conexiones de ancho de banda variante en el tiempo. El primer tópico analiza la posibilidad de agregar conexiones originadas en la misma fuente pero con diferentes destinos dentro de una EON, con el objetivo de ahorrar recursos tanto en cuanto a número de equipos transmisores utilizados como en el espectro utilizado. Se ha propuesto un nuevo algoritmo que mejora ambos parámetros, así como una arquitectura para los nodos de la red que permite utilizar el algoritmo de agregación propuesto de manera eficiente desde el punto de vista del coste. Se consigue una considerable mejora en cuanto a la utilización del espectro además de una significativa reducción en el número de trasmisores por nodo que se requieren. El problema de la fragmentación espectral en las EONs se ataca en la segunda aportación de esta Tesis. Se ha conseguido demostrar la correlación entre la óptima (es decir, mínima) periodicidad de las acciones de desfragmentación y la granularidad del tráfico soportado. Se ha propuesto un nuevo algoritmo para una desfragmentación eficiente, el objetivo del cual es consolidar el espectro disponible en las fibras tanto como sea posible, al mismo tiempo que se reduce el número de conexiones que deben ser reubicadas en la red. Se demuestra que, en una EON, se puede configurar de manera óptima la periodicidad de las desfragmentaciones si se conoce la granularidad de las conexiones a transportar. Finalmente, en el tercer gran apartado de la Tesis, se estudia la posibilidad de utilizar la fragmentación espectral en las EON para una mejor asignación de los recursos cuando el tráfico es variante en el tiempo. En este contexto, se ha propuesto y validado un algoritmo de asignación del espectro (SA) que incrementa de manera intencionada la fragmentación espectral de la red. En esta propuesta, el espectro asignado a cada nueva conexión se ubica en medio del vacío espectral más grande que se encuentra en toda la ruta, con el objetivo de dejar tanto espacio como sea posible entre las diferentes conexiones. Este espacio es después utilizado para conexiones que requieren, a lo largo de su existencia, más espectro del que se les ha asignado inicialmente (incrementan su ancho de banda). Los resultados obtenidos mediante simulaciones muestran significantes mejoras en términos de Probabilidad de Bloqueo (BP) de la red cuando se utiliza el algoritmo propuesto. Después de una introducción a la Tesis, el Capitulo 2 ofrece una revisión de la evolución delas redes ópticas de transporte, introduciendo el concepto de red óptica elástica (EON). El Capítulo 3 se centra en el estudio de los métodos de encaminamiento y asignación de longitud de onda en redes WDM convencionales, y su evolución hacia el problema de la asignación de espectro (RSA) en EONs. El Capítulo 4 detalla los estudios y las contribuciones hechas en el tema de agregación de conexiones de granularidad inferior a la longitud de onda en EONs. El algoritmo propuesto, así como la arquitectura de nodo que permite aplicarlo, se presentan en este Capitulo. El problema de la fragmentación espectral en las EONs y sus soluciones se revisan a fondo en el Capitulo 5. La correlación entre la periodicidad de las desfragmentaciones espectrales y la granularidad del tráfico ofrecido se estudian aquí. El Capitulo 6 detalla el problema de servir conexiones variantes en el tiempo en EONs. Algunas políticas propuestas hasta ahora se han revisado, y a continuación se propone una que, en algunos aspectos, mejora las previamente publicadas. Finalmente, hay que destacar que este trabajo ha recibido el apoyo del Gobierno de la Generalitat de Catalunya, a través de una beca FI-AGAUR, y que se ha realizado en el marco del proyecto ELASTIC (*TEC2011-27310), del Ministerio de Educación Ciencia y Deporte Español.

  • Grup de comunicacions òptiques

     Junyent Giralt, Gabriel; Prat Goma, Josep; Ruiz Moreno, Sergio; Soneira Ferrando, M. Jose; Spadaro, Salvatore; Santos Blanco, María Concepción; Gené Bernaus, Joan M.; Lazaro Villa, Jose Antonio; Velasco Esteban, Luis; Pérez Pueyo, Rosanna; Segarra Mullerat, Josep; Polo Querol, Victor Manuel; Agraz Bujan, Fernando; Ruiz Ramírez, Marc; Cano Valadez, Ivan Nicolas; Sales Zaragoza, Vicente; Khodashenas, Pouria Sayyad; Pages Cruz, Albert; Castro Casales, Alberto; Gifre Renom, Lluis; Tabares Giraldo, Jeison; Escayola Elias, Francisco Javier; Chu, Guangyong; Comellas Colome, Jaume
    Competitive project

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  • On the performance of dynamic source aggregation of sub-wavelength connections in EONs

     Khodashenas, Pouria Sayyad; Comellas Colome, Jaume; Perello Muntan, Jordi; Spadaro, Salvatore; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. 6876273-1-6876273-4
    DOI: 10.1109/ICTON.2014.6876273
    Presentation's date: 2014-07
    Presentation of work at congresses

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    In elastic optical networks, heterogeneous traffic demands are typically supported by a single type of bandwidth-variable transmitters, which is not always spectrum and cost efficient. In light of this, we recently proposed a novel algorithm for dynamic aggregation of same source but different destination sub-wavelength connections in elastic optical networks, aiming to obtain both transmitter and spectrum usage savings. In this paper, the performance and feasibility analysis of the proposal is presented. The obtained results demonstrate considerable improvement in the network spectrum utilization, as well as a significant reduction in the relative network cost.

  • A comparison of elastic and multi-rate optical networks performance

     Khodashenas, Pouria Sayyad; Pomares, D.; Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 6876268-1-6876268-4
    DOI: 10.1109/ICTON.2014.6876268
    Presentation's date: 2014-07
    Presentation of work at congresses

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    While Elastic Optical Networks (EONs) have recently emerged as a promising solution to cope with the growth and heterogeneity of data traffic, there are some drawbacks that have attracted the researchers' attention. One of such flaws is spectrum fragmentation, which has generated many controversial as it imposes huge number of extra actions during network operation. Some intermediate proposals have been disclosed, such as semi-elastic schemes that approach the performance of EONs while keeping the spectral entropy restrained. The purpose of this paper is to present a comparison between EONs and semi-elastic networks, where all the offered connections are allocated using only three different channel rate options. Different spectrum management strategies are introduced and evaluated by means of simulation considering both scenarios.

  • A GRASP with path-relinking heuristic for the survivable IP/MPLS-over-WSON multi-layer network optimization problem

     Pedrola Escriba, Oscar; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Careglio, Davide; Gonzalez de Dios, Oscar; Comellas Colome, Jaume
    Computers & operations research
    Vol. 40, num. 12, p. 3174-3187
    DOI: 10.1016/j.cor.2011.10.026
    Date of publication: 2013-12
    Journal article

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    In this paper we deal with the survivable internet protocol (IP)/multi-protocol label switching (MPLS)-over-wavelength switched optical network (WSON) multi-layer network optimization problem (SIMNO). This problem entails planning an IP/MPLS network layer over a photonic mesh infrastructure whilst, at the same time, ensuring the highest availability of services and minimizing the capital expenditures (CAPEX) investments. Such a problem is currently identified as an open issue among network operators, and hence, its solution is of great interest. To tackle SIMNO, we first provide an integer linear programming (ILP) formulation which provides an insight into the complexity of its managing. Then, a greedy randomized adaptive search procedure (GRASP) with path-relinking (PR) together with a biased random-key genetic algorithm (BRKGA) are specifically developed to help solve the problem. The performance of both heuristics is exhaustively tested and compared making use of various network and traffic instances. Numerical experiments show the benefits of using GRASP instead of BRKGA when dealing with highly complex network scenarios. Moreover, we verified that the use of GRASP with PR remarkably improves the basic GRASP algorithm, particularly in real-sized, complex scenarios such as those proposed in this paper.

  • Elastic spectrum allocation for time-varying traffic in flexgrid optical networks

     Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Careglio, Davide; López Álvarez, Victor; Comellas Colome, Jaume
    IEEE journal on selected areas in communications
    Vol. 31, num. 1, p. 26-38
    DOI: 10.1109/JSAC.2013.130104
    Date of publication: 2013-01
    Journal article

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  • A column generation approach for large-scale RSA-based network planning

     Ruiz Ramírez, Marc; Zotkiewicz, Mateusz; Velasco Esteban, Luis; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2013.6603034
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In flexgrid-based optical networks, the problem of finding optimal route and spectrum allocation (RSA) for the demands in a traffic matrix becomes harder to solve than similar problems in fixed DWDM networks, mainly due to the finer spectrum granularity and the spectrum contiguity and continuity constraints. Additionally, the increasing traffic volumes and the size of real networks lead to network planning problem instances consisting of hundreds of thousands, or even millions, of (binary) variables. In this work, we present a column generation decomposition method to obtain feasible solutions for RSA-based network planning problems. Numerical results show the utility of this method for solving intractable instances.

  • A traffic intensity model for flexgrid optical network planning under dynamic traffic operation

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    DOI: 10.1364/OFC.2013.OTu3A.6
    Presentation's date: 2013-03
    Presentation of work at congresses

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    We obtain a model to estimate the highest traffic intensity that a flexgrid-based network can support in dynamic scenarios. A design problem is introduced to illustrate its application. Numerical results validate both accuracy and utility.

  • An elastic networks OMNeT++-based simulator

     Asensio Garcia, Adrian; Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. Tu.C1.2-1-Tu.C1.2-4
    DOI: 10.1109/ICTON.2013.6602814
    Presentation's date: 2013-06
    Presentation of work at congresses

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    An increasing number of studies about flexgrid-based elastic optical networks are currently being carried out by industry as well as academic research teams. As access to real test-beds is limited, there is a lack of effective tools that emulate realistic scenarios for testing algorithms and network architectures. In this paper, we present a simulation framework based on an active stateful Path Computation Element (PCE) with Global Concurrent Optimization (GCO) for flexgrid optical networks. The simulator is fully configurable and allows implementing and testing new algorithms and architectures easily and quickly.

  • Global concurrent optimization: advantages and opportunities in flexgrid-based networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. Mo.C4.1-1-Mo.C4.1-4
    DOI: 10.1109/ICTON.2013.6602714
    Presentation's date: 2013-06
    Presentation of work at congresses

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    In future flexgrid core networks the amount of lightpaths might increase significantly as a consequence of the finer granularity in the use of the optical spectrum. Different spectrum bandwidth can be allocated to each lightpath as a function of, among others, the bitrate amount to be conveyed and the modulation format used. As result, spectrum fragmentation might appear leading to non-optimal resource utilization. In addition, a failure in a fibre link could trigger hundreds, or even thousands, of path computations requests to a centralized Path Computation Element (PCE). Latter examples can benefit from using the recently standardized Global Concurrent Optimization (GCO), which enhances PCE's computation capabilities. In this paper we present two opportunities to take advantage of the PCE+GCO architecture: spectrum defragmentation and restoration.

  • Dynamic restoration in multi-layer IP/MPLS-over-flexgrid networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Design of Reliable Communication Networks (DRCN)
    p. 155-162
    Presentation's date: 2013-03
    Presentation of work at congresses

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    The recent advances in photonic technology will allow deploying flexgrid-based optical core networks in the near future. Although that technology favors more efficient spectrum utilization, multilayer IP/MPLS-over-flexgrid networks would still be needed to groom together client flows, coming from access and metro networks, into optical connections. In this scenario, multi-flow transponders (MF-TPs) will provide additional flexibility allowing reconfiguration of optical connections to be performed. To be operated, a distributed control plane together with a centralized Path Computation Element (PCE) could be used. In the event of a failure, tens or hundreds of client flows could become disconnected and thus, restoration routes need to be found by the PCE for these flows. In standard restoration, path computation for each client flow is performed which derives into resource contention as a result of several connections trying to use some common resources, and poor resource utilization as a result of the reduction of grooming levels. In this paper, we deal with these problems and solve the DYNamic restorAtion in Multi-layer IP/MPLS-over-flexgrid Optical networks (DYNAMO) problem. Client flows' restoration requests are grouped into a single bulk in the PCE. Afterwards, a Global Concurrent Optimization (GCO) module solves the DYNAMO problem finding routes for all the flows in the bulk. The DYNAMO problem is modeled by using mathematical programming. However, as a consequence of its complexity and the stringent times within which the problem has to be solved, a GRASP-based heuristic is used. Exhaustive simulation results performed on two national core topologies show that a PCE with a GCO module solving DYNAMO highly improves restorability and reduces remarkably the number and capacity of MF-TPs, at the expense of some increment in restoration times.

  • Impact of aggregation level on the performance of dynamic lightpath adaptation under time-varying traffic

     Asensio Carmona, Adrian; Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Lopez, Victor Bohorquez; Castro Casales, Alberto; Velasco Esteban, Luis; Comellas Colome, Jaume
    International Conference on Optical Network Design and Modeling
    p. 184-189
    Presentation's date: 2013-04
    Presentation of work at congresses

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    In this article we focus on lightpath adaptation under time-varying traffic in a dynamic elastic optical network (EON) implementing flexgrid optical technology. In the considered scenario, a number of IP/MPLS metro area networks performing traffic aggregation are connected through a core EON. We explore the elastic spectrum allocation (SA) capability of EON and, in this context, we study the effectiveness of three alternative SA policies, namely Fixed, Semi-Elastic and Elastic. For each elastic SA policy, we develop a dedicated algorithm which is responsible for adaptation of spectrum allocated to lightpath connections in response to traffic changes. The evaluation is performed for a set of network scenarios, each one characterized by a different level of traffic aggregation, and hence different traffic variability. As simulation results show, the effectiveness of SA policies highly depends on both the aggregation level and maximum lightpath capacity. In particular, in our experiments up to 21% more traffic is served with the proposed elastic SA than with the fixed SA in a network with low aggregation and high lightpath capacity

    In this article we focus on lightpath adaptation under time-varying traffic in a dynamic elastic optical network (EON) implementing flexgrid optical technology. In the considered scenario, a number of IP/MPLS metro area networks performing traffic aggregation are connected through a core EON. We explore the elastic spectrum allocation (SA) capability of EON and, in this context, we study the effectiveness of three alternative SA policies, namely Fixed, Semi-Elastic and Elastic. For each elastic SA policy, we develop a dedicated algorithm which is responsible for adaptation of spectrum allocated to lightpath connections in response to traffic changes. The evaluation is performed for a set of network scenarios, each one characterized by a different level of traffic aggregation, and hence different traffic variability. As simulation results show, the effectiveness of SA policies highly depends on both the aggregation level and maximum lightpath capacity. In particular, in our experiments up to 21% more traffic is served with the proposed elastic SA than with the fixed SA in a network with low aggregation and high lightpath capacity.

  • Extending the flexgrid optical core towards the edges

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Castro Casales, Alberto; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2013.6602717
    Presentation of work at congresses

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    National IP/MPLS network have being designed on top of fixed-grid DWDM optical networks so to spread out covering large areas. Besides, multilayer IP/MPLS-over-DWDM networks take advantage from grooming to achieve high spectrum efficiency, filling the gap between users' flows and wavelength channels' capacity. The advent of the flexgrid technology providing a finer granularity makes possible to perform grooming also at the optical layer. We propose to flatten previous multilayer approaches and advance towards single layer networks consisting in a number of IP/MPLS areas connected through a flexgrid-based core network. A two-step procedure to design such flexgrid-based IP/MPLS national networks is proposed. In this paper, a future large flexgrid core network inter-connecting small areas is shown.

  • Experimental validation of dynamic restoration in GMPLS-controlled multi-layer networks using PCE-based global concurrent optimization

     Martínez, Ricardo; Castro Casales, Alberto; Casellas Regi, Ramón; Muñoz González, Raul; Velasco Esteban, Luis; Vilalta, Ricardo; Comellas Colome, Jaume
    Optical Fiber Communication Conference and Exposition and National Fiber Optic Engineers Conference
    p. 1-3
    DOI: 10.1364/OFC.2013.OW4G.3
    Presentation's date: 2013
    Presentation of work at congresses

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    An experimental validation of a PCE-based GCO architecture for dynamic restoration in GMPLS multi-layer networks is presented. This solution better addresses the concurrence of multiple connection requests favoring grooming objectives and attaining higher restorability.

  • Value optimization of survivable multilayer IP/MPLS-over-WSON networks

     Velasco Esteban, Luis; González de Dios, Óscar; Ricciardi, Sergio; Castro Casales, Alberto; Muñoz, Fernando; Careglio, Davide; Comellas Colome, Jaume
    Photonic network communications
    Vol. 23, num. 3, p. 246-258
    DOI: 10.1007/s11107-011-0354-7
    Date of publication: 2012-05-01
    Journal article

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  • Modeling the routing and spectrum allocation problem for flexgrid optical networks

     Velasco Esteban, Luis; Klinkowski, Miroslaw; Ruiz Ramírez, Marc; Comellas Colome, Jaume
    Photonic network communications
    Vol. 24, num. 3, p. 177-186
    DOI: 10.1007/s11107-012-0378-7
    Date of publication: 2012-12
    Journal article

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  • Enhanced optical networks featuring adaptable and highly scalable multi-granular transport services

     Ruiz Ramírez, Marc; Junyent Giralt, Gabriel; Comellas Colome, Jaume; Gené Bernaus, Joan M.; Conesa Fernandez, Josep; Velasco Esteban, Luis; Perello Muntan, Jordi; Agraz Bujan, Fernando; Hernandez Sola, Guillem; Pages Cruz, Albert; Khodashenas, Pooria Saiyad; Spadaro, Salvatore
    Competitive project

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  • Enhanced Optical Networks Featuring Adaptable and Highly Scalable Multi-granular Transport Services (ELASTIC) - TEC2011-27310

     Junyent Giralt, Gabriel; Spadaro, Salvatore; Comellas Colome, Jaume; Gené Bernaus, Joan M.; Velasco Esteban, Luis; Perello Muntan, Jordi; Conesa Fernandez, Josep; Agraz Bujan, Fernando; Ruiz Ramírez, Marc; Hernandez Sola, Guillem; Pages Cruz, Albert; Khodashenas, Pooria Saiyad
    Competitive project

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  • Industry-Driven Elastic and Adaptive Lambda Infrastructure for Service and Transport Networks

     Ruiz Ramírez, Marc; Castro Casales, Alberto; Comellas Colome, Jaume; Junyent Giralt, Gabriel; Gifre Renom, Lluis; Velasco Esteban, Luis
    Competitive project

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  • Single-path provisioning with multi-path recovery in flexgrid optical networks

     Castro Casales, Alberto; Velasco Esteban, Luis; Ruiz Ramírez, Marc; Comellas Colome, Jaume
    International Congress on Ultra Modern Telecommunications and Control Systems and Workshops
    p. 745-751
    DOI: 10.1109/ICUMT.2012.6459763
    Presentation's date: 2012-05-03
    Presentation of work at congresses

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    The new flexgrid technology, in opposition to the fixed grid one traditionally used in wavelength switched optical networks (WSON), allows allocating the spectral bandwidth needed to convey heterogeneous client demand bitrates in a flexible manner so that the optical spectrum can be managed much more efficiently. In this paper we propose a new recovery scheme, called single-path provisioning multi-path recovery (SPP-MPR), specifically designed for flexgrid-based optical networks. It provisions single-paths to serve the bitrate requested by client demands and combines protection and restoration schemes to jointly recover, in part or totally, that bitrate in case of failure. We define the bitrate squeezed recovery optimization (BRASERO) problem to maximize the bitrate which is recovered in case of failure of any single fiber link. A mixed integer linear programming (MILP) formulation is provided. Exhaustive numerical experiments carried out over two network topologies and realistic traffic scenarios show that the efficiency of the proposed SPP-MPR scheme approaches that of restoration mechanisms while providing recovery times as short as protection schemes.

  • Access to the full text
    Experimental evaluation of a dynamic PCE-based regenerator-efficient IA-RWA algorithm in translucent WSON  Open access

     Castro Casales, Alberto; Martínez, Ricardo; Velasco Esteban, Luis; Casellas Regi, Ramón; Muñoz González, Raul; Comellas Colome, Jaume
    European Conference and Exhibition on Optical Communication
    p. 1-3
    DOI: 10.1364/ECEOC.2012.Tu.4.D.3
    Presentation's date: 2012-09
    Presentation of work at congresses

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    Abstract (40-Word Limit): We devise a novel dynamic PCE-based impairment-aware RWA algorithm in translucent GMPLS WSON that minimizes regenerator usage. Experimental evaluation carried out on the Open GMPLS/PCE control plane of CTTC ADRENALINE test-bed shows that significant improvements (>340%) are attained in terms of the offered traffic load.

    We devise a novel dynamic PCE-based impairment-aware RWA algorithm in translucent GMPLS WSON that minimizes regenerator usage. Experimental evaluation carried out on the Open GMPLS/PCE control plane of CTTC ADRENALINE test-bed shows that significant improvements (>340%) are attained in terms of the offered traffic load.

  • On the performance of flexgrid-based optical networks

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Pedrola Escriba, Oscar; Castro Casales, Alberto; Klinkowski, Miroslaw; Careglio, Davide; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2012.6254418
    Presentation's date: 2012-07
    Presentation of work at congresses

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    The ever increasing IP traffic volume has finally brought to light the high inefficiency of current wavelength-routed rigid-grid networks in matching the client layer requirements. Such an issue results in the deployment of large-size, expensive and power-consuming IP/MPLS layers to perform the required grooming/aggregation functionality. To deal with this problem, the emerging flexgrid technology, allowing for reduced size frequency grids, usually referred to as frequency slot, has recently attracted great attention among network operators, component and equipment suppliers, and the research community. In this paper, we report the main contributions performed in the context of EU STRONGEST project regarding flexgrid optical networks.

  • Path-based recovery in flexgrid optical networks

     Castro Casales, Alberto; Ruiz Ramírez, Marc; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2012.6254479
    Presentation's date: 2012
    Presentation of work at congresses

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    With the advent of flexgrid optical networks, the rigid wavelength-division multiplexing (WDM) technology will be enhanced by providing better spectrum efficiency and flexibility. In those future flexible optical networks, optical connections (lightpaths) can allocate a flexible number of spectrum slices, also known as frequency slots, so to match better with its requested bitrate. In this paper, we propose to take advantage of this flexible spectrum allocation in recovery mechanisms to be triggered when a failure occurs to provide recovery of part of the requested bitrate, i.e. the allocated spectrum by backup lightpaths could be lower than that of the working lightpaths provided that client service level agreements are fulfilled. This reduction in the recovered bitrate (bitrate squeezing) allows optimizing the use of network capacity. We propose path-based recovery alternatives, based on protection and restoration, specially designed for flexgrid networks. The performance of the proposed recovery mechanisms is exhaustively evaluated on a national reference network

  • GMPLS control plane network design with resilience guarantees

     Ruiz Ramírez, Marc; Perello Muntan, Jordi; Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Journal of lightwave technology
    Vol. 29, num. 1, p. 37-47
    DOI: 10.1109/JLT.2010.2090648
    Date of publication: 2011-01-01
    Journal article

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    A one-to-one association between data and control channels has traditionally existed in transport networks. Being the control plane embedded in the data plane, the design of the former, as well as its resilience, has been addressed in the latter’s one. However, a main GMPLS architectural requirement is to provide a clean separation between control and data planes. In this sense, the control plane in GMPLS networks may describe a different topology than the data plane, even realized over a separated IP network. As a consequence of this, data and control network design become no more linked in such scenarios. To the best of our knowledge, no works in the literature have addressed an independent design of the control plane in GMPLS-enabled networks regardless of the data plane. In this paper, we provide a method to obtain the optimal GMPLS control plane design, minimizing the network Capital Expenditures (CAPEX) while matching specific resilience requirements. To this goal, the problem of finding an optimal control plane topology that ensures a certain resilience level is formulated as a non-linear combinatorial model. This model, however, does not scale properly for large backbone networks. In view of this, a constructive linear method is also presented and its optimality validated through simulations on several reference network scenarios. Furthermore, its benefits in terms of total execution time are also highlighted.

  • Access to the full text
    Service and resource differentiation in shared-path protection environments to maximize network operator's revenues  Open access

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume
    Journal of optical communications and networking
    Vol. 3, num. 2, p. 117-126
    DOI: 10.1364/JOCN.3.000117
    Date of publication: 2011-02
    Journal article

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    Network operators are facing hard competition for opportunities in the telecommunications market, forcing network investments to be carefully evaluated before the decision-making process. A great part of core network operators’ revenues comes from the provisioned connectivity services. Taking this premise as our starting point, we first examine the provisioning of differentiated services in current shared-path protection (SPP) environments. This analysis reveals that current resource assignment policies are only able to provide a very poor grade of service to the supported best-effort traffic. Aiming to improve this performance, a novel resource partitioning scheme called diff-WS is proposed, which differentiates those wavelengths supporting each class of service in the network. As a major goal of this paper, the benefits of diff-WS over current resource assignment policies are assessed from an economic perspective. For this purpose, the network operator revenues maximization (NORMA) problem is presented to design the optical network such that the operator’s revenues are maximized. To solve NORMA, we derive statistical models to obtain, given a certain grade of service, the highest traffic intensity for each class of service and resource partitioning scheme. These models turn NORMA into a nonlinear problem, which is finally addressed as an iterative approach, solving an integer linear programming (ILP) subproblem at each iteration. The obtained numerical results on several network topologies illustrate that diff-WS maximizes resource utilization in the network and, thus, the network operator’s profit.

  • A feedback-based hybrid OBS/OCS architecture with fast-over-slow capability

     Khodashenas, Pooria Saiyad; Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Optical Network Design and Modeling
    Presentation's date: 2011-02-08
    Presentation of work at congresses

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  • NORMA: Network Operator Revenues Maximization

     Velasco Esteban, Luis; Ruiz Ramírez, Marc; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2011.5970938
    Presentation's date: 2011-05-27
    Presentation of work at congresses

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    A great part of core network operators’ gross profit comes from the provisioned connectivity services. In this work, we analyze the provisioning of differentiated services in current Shared Path Protection (SPP) environments. This analysis concludes that, with current resource assignment policies, only a very poor grade of service can be provided to the carried best effort traffic. Hence, we propose diff-WS, a resource partitioning scheme that differentiates those wavelengths supporting each class of service in the network. The benefits of diff-WS in front of current resource assignment policies are afterwards evaluated from an economic perspective. To this goal, we define the NORMA problem as a revenue maximization problem. To solve NORMA, we introduce statistical models to obtain, for a given grade of service, the highest traffic intensity for each supported class of service and resource assignment scheme. From the numerical results, we show that diff-WS maximizes resource utilization in the network and, thus, network operator’s profit.

  • Scalable hybrid path computation procedure for PCE-based multi-domain WSON networks

     Hernandez Sola, Guillem; Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2011.5970767
    Presentation's date: 2011
    Presentation of work at congresses

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    In the Hierarchical Path Computation Element (H-PCE) architecture, an optimum end-to-end path is computed using a hierarchical relationship among PCEs. An H-PCE-based path computation procedure provides low network blocking probability meanwhile it results on a great amount of control overhead messages. In this paper we propose a hybrid path computation procedure based on the H-PCE architecture and the Backward Recursive PCE-Based Computation (BRPC). Extensive simulation results show that the proposed approach performs better than H-PCE in terms of network control overhead.

  • Scalable hybrid path computation procedure for PCE-based

     Hernandez Sola, Guillem; Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. 1-4
    Presentation's date: 2011-06-27
    Presentation of work at congresses

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  • Optical network net present value optimization in shared path protection environments

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Design of Reliable Communication Networks
    p. 38-45
    DOI: 10.1109/DRCN.2011.6076883
    Presentation's date: 2011-10-10
    Presentation of work at congresses

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    Network operators are facing hard competition for opportunities in the telecommunications market, thus network investments must be carefully evaluated from the costs and revenues viewpoint before the decision making process. Since a great part of core network operators’ revenues comes from the provisioned connectivity services, in this work we study the value expected to generate by optical networks when provisioning differentiated services in Shared Path Protection (SPP) environments. In this regard, two wavelength partitioning schemes are compared: the shared (sh-WS) and the differentiated (diff-WS). The benefits of both schemes are evaluated from an economic perspective defining costs and revenues models and using Net Present Value (NPV). We define the Optical Network NPV Optimization (OVALO) problem as a NPV maximization problem. To solve OVALO, a linearized version of NPV is proposed as objective function of the Integer Linear Programming (ILP) model and an iterative algorithm is used to finally solve OVALO. The partitioning schemes are numerically compared on two network topologies. From the results, we show that diff-WS maximizes resource utilization in the network without significantly increasing network costs, thus maximizing the network’s value.

  • A GRASP-based heuristic to design the GMPLS control plane network topology with resilience guarantees

     Ruiz Ramírez, Marc; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. Mo.B3.4-1-Mo.B3.4-4
    DOI: 10.1109/ICTON.2011.5970780
    Presentation's date: 2011-06-28
    Presentation of work at congresses

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    The control plane topology has traditionally followed that of the data plane and therefore the design of the former, as well as its resilience, has been addressed in the latter's one. Owing to the fact that a clear separation between control and data planes is a main GMPLS architectural requirement, the control plane in GMPLS networks may describe a different topology than the data plane, even realized over a separated IP network. As a consequence of this, data and control network design become no more linked in such scenarios. In this paper, we design a heuristic algorithm to obtain the optimal GMPLS control plane design, minimizing the network Capital Expenditures (CAPEX) while matching specific resilience requirements. The performance of the heuristic algorithm is compared with exact solutions obtained by solving an Integer Linear Programming (ILP) model on several reference network scenarios. Furthermore, its benefits in terms of total execution time are also highlighted.

  • Mixed integration of CDIO skills into telecommunication engineering curricula

     Sayrol Clols, Elisa; Bragos Bardia, Ramon; Alarcon Cot, Eduardo Jose; Cabrera Bean, Margarita Asuncion; Calveras Auge, Ana M.; Comellas Colome, Jaume; O'callaghan Castella, Juan Manuel; Pegueroles Valles, Josep Rafel; Pla, E; Prat Viñas, Luis; Saez Moreno, German; Sarda Ferrer, Joan; Tallon Montoro, Carme
    Elektronika ir elektrotechnika
    Vol. 6, num. 102, p. 127-130
    Date of publication: 2010
    Journal article

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  • Using updated neighbor state information for efficient contention avoidance in OBS networks

     Perello Muntan, Jordi; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Computer communications
    Vol. 33, num. 1, p. 65-72
    DOI: 10.1016/j.comcom.2009.08.002
    Date of publication: 2010-01
    Journal article

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  • Scalable path computation flooding approach for PCE-based multi-domain networks

     Perello Muntan, Jordi; Hernandez Sola, Guillem; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume
    ETRI journal
    Vol. 32, num. 4, p. 622-625
    DOI: 10.4218/etrij.10.0210.0063
    Date of publication: 2010-08
    Journal article

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  • Scalable, Tunable and Resilient Optical Networks Guaranteeing Extremely-high Speed Transport

     Spadaro, Salvatore; Sole Pareta, Josep; Perello Muntan, Jordi; Careglio, Davide; Velasco Esteban, Luis; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Competitive project

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  • projecte GEYSERS

     Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume; Perello Muntan, Jordi
    Competitive project

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  • Experimental UpdateLess Evolutive Routing

     Junyent Giralt, Gabriel; Comellas Colome, Jaume; Cabellos Aparicio, Alberto; Careglio, Davide; Perello Muntan, Jordi; Sole Pareta, Josep; Spadaro, Salvatore
    Competitive project

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  • Deployment and validation of GMPLS-controlled multi-layer integrated routing over the ASON/GMPLS CARISMA test-bed

     Agraz Bujan, Fernando; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Journal of networks
    Vol. 5, num. 11, p. 1321-1327
    DOI: 10.4304/jnw.5.11.1321-132
    Date of publication: 2010-11
    Journal article

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  • Access to the full text
    Proceso de inversión de competencias genéricas en los nuevos planes de estudios de grado de la ETSETB de acuerdo con el modelo CDIO  Open access

     Bragos Bardia, Ramon; Alarcon Cot, Eduardo Jose; Cabrera Bean, Margarita Asuncion; Calveras Auge, Ana M.; Comellas Colome, Jaume; O'callaghan Castella, Juan Manuel; Pegueroles Valles, Josep Rafel; Prat Viñas, Luis; Saez Moreno, German; Sarda Ferrer, Joan; Sayrol Clols, Elisa
    Congreso de Tecnologías Aplicadas a la Enseñanza de la Electrónica
    p. 1-9
    Presentation's date: 2010-04-13
    Presentation of work at congresses

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    Los distintos marcos normativos que fijan las condiciones de contorno en la elaboración de los nuevos planes de estudios ponen especial énfasis en el aprendizaje basado en competencias y en la inclusión de determinadas competencias genéricas. Después de comparar diversos planes de estudio y listados de competencias, se han establecido las competencias genéricas que deben incluir los nuevos grados de la ETSETB de la UPC y se ha diseñado su estructura para favorecer su aprendizaje. Para ello se ha utilizado como paradigma el modelo CDIO (Conceive, Design, Implement, Operate).

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    Analysis of traffic engineering information dissemination strategies in PCE-based multi-domain optical networks  Open access

     Spadaro, Salvatore; Perello Muntan, Jordi; Hernandez Sola, Guillem; Moreno, A.; Agraz Bujan, Fernando; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2010.5549261
    Presentation's date: 2010-06-28
    Presentation of work at congresses

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    This paper presents and compares different TE information dissemination strategies between Path Computation Elements (PCEs) in multi-domain optical networks. In such network context, recent studies have found that path computation only with local domain visibility yields poor network performance. Accordingly, certain visibility between domains seems necessary. Aiming to fit the confidentiality requirements of the composing domains while improving the final network blocking probability, novel link aggregation techniques have been proposed, which summarize the state of network domains resources efficiently. This aggregated link information is afterwards disseminated to all the remainder domains in the network. To this end, we introduce different update triggering policies to make a good trade-off between routing information scalability and inaccuracy. The performance of all contributions has been supported by illustrative simulation results.

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    Performance evaluation of a hybrid OBS/OCS network with QoS differentiation based on packet loss/delay requirements  Open access

     Perello Muntan, Jordi; Guinea, Nuria de; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    International Conference on Transparent Optical Networks
    p. 1-4
    DOI: 10.1109/ICTON.2010.5549287
    Presentation's date: 2010-06-28
    Presentation of work at congresses

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    This paper introduces and evaluates a hybrid OBS/OCS switch for Quality of Service (QoS) differentiation in next-generation all-optical transport networks. Depending on their QoS requirements, incoming IP packets are collected in delay-sensitive or loss-sensitive assembly queues. Once assembled, those departing delay or losssensitive bursts are sent to the destination over a parallel all-optical hybrid network, where a set of switch ports and wavelengths are dedicated to delay-sensitive OBS-like transmission based on Just Enough Time (JET), whereas the remainder are dedicated to loss-sensitive OCS-like transmission. The obtained results validate the differentiated transport services in the deployed reference network scenario. Moreover, they show that circuit set-up retries are mandatory in OCS to carry loss-sensitive traffic efficiently.

  • ENGINEERING NEXT GENERATION OPTICAL TRANSPORT NETWORKS

     Comellas Colome, Jaume; Junyent Giralt, Gabriel; Conesa Fernandez, Josep; Gené Bernaus, Joan M.; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore
    Competitive project

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  • Shared-path protection with extra traffic in ASON¿GMPLS ring networks

     Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    Journal of optical networking
    Vol. 8, num. 2, p. 130-145
    Date of publication: 2009-01
    Journal article

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  • Controlled loops for quality-of-service differentiation in delay-sensitive optical burst switching networks

     Perello Muntan, Jordi; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    IET communications
    Vol. 3, num. 8, p. 1263-1273
    Date of publication: 2009-08
    Journal article

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    An analytical model for GMPLS control plane resilience quantification  Open access

     Ruiz Ramírez, Marc; Perello Muntan, Jordi; Velasco Esteban, Luis; Spadaro, Salvatore; Comellas Colome, Jaume
    IEEE communications letters
    Vol. 13, num. 12, p. 977-979
    DOI: 10.1109/LCOMM.2009.12.091550
    Date of publication: 2009-12
    Journal article

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    This paper concentrates on the resilience of the Generalized Multi-Protocol Label Switching (GMPLS) enabled control plane. To this end, the problem of control plane resilience in GMPLS-controlled networks is firstly stated and previous work on the topic reviewed. Next, analytical formulae to quantify the resilience of generic meshed control plane topologies are derived. The resulting model is validated by simulation results on several reference network scenarios.

  • A Dynamic Impairment-Awate Networking Solution for Transparent Mesh Optical Networks

     Comellas Colome, Jaume; Sole Pareta, Josep
    IEEE communications magazine
    Vol. 47, num. 5, p. 38-47
    Date of publication: 2009-05
    Journal article

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    Design and implementation of a GMPLS-controlled grooming-capable optical transport network  Open access

     Agraz Bujan, Fernando; Velasco Esteban, Luis; Perello Muntan, Jordi; Ruiz Ramírez, Marc; Spadaro, Salvatore; Junyent Giralt, Gabriel; Comellas Colome, Jaume
    Journal of optical communications and networking
    Vol. 1, num. 2, p. A258-A269
    DOI: 10.1364/JOCN.1.00A258
    Date of publication: 2009-07
    Journal article

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    Aiming at better resource utilization, an important requirement of future optical transport networks is the capability to accommodate subwavelength client flows efficiently. This can be put into action thanks to the enhanced traffic engineering (TE) protocols provided within the generalized multiprotocol label switching (GMPLS) standardization. The present paper concentrates on the design and implementation of a GMPLS-controlled grooming-capable transport infrastructure, namely, the automatically switched optical network (ASON)ÕGMPLS CARISMA test bed. Through the paper, the operation of a GMPLS-controlled multilayer network architecture is introduced, subsequently highlighting implementation issues that come to light. Special attention is devoted to a centralized flow reallocation module deployed in the CARISMA test bed to minimize the overall network cost. In this context, an integer linear programming (ILP) formulation to obtain its optimal cost is derived and low-weighted metaheuristics providing a nearly optimal solution are additionally proposed. All contributions in the paper are supported by illustrative experimental results.

  • Demonstration of GMPLS-controlled Integrated IP/WDM routing over a Grooming-capable ASON/GMPLS Network Test-bed

     Perello Muntan, Jordi; Velasco Esteban, Luis; Agraz Bujan, Fernando; Spadaro, Salvatore; Comellas Colome, Jaume; Junyent Giralt, Gabriel
    European Conference on Optical Communication
    p. 1-2
    Presentation's date: 2009-09-22
    Presentation of work at congresses

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