Smart Algorithms for Hierarchical Clustering in Optical Network

Network design process is a very important in order to balance between the investment in the network and the supervises offered to the network user, taking into consideration, both minimizing the network investment cost, on the other hand, maximizing the quality of service offered to the customers as well.Partitioning the network to smaller sub-networks called clusters is required during the design process inorder to ease studying the whole network and achieve the design process as a trade-off between several atrtributes such as quality of service, reliability,cost, and management. Under CANON, a large scale optical network is partitioned into a number of geographically limited areas taking into account many different criteria like administrative domains, topological characteristics, traffic patterns, legacy infrastructure etc. An important consideration is that each of these clusters is comprised of a group of nodes in geographical proximity. The clusters can coincide with administrative domains but there could be many cases where two or more clusters belong to the same administrative domain. Therefore, in the most general case the partitioning into specific clusters can be either a off-line or a on-line process. In this work only the off-line case is considered. In this Study, we look at the problem of designing efficient 2- level Hierarchical Optical Networks (HON), in the context of network costs optimization. 2-level HON paradigm only have local rings to connect disjoint sets of nodes and a global sub mesh to interconnect all the local rings. We present an Hierarchical algorithm that is based on two phases. We present results for scenarios containing a set of real optical topologies

Benchmarking and viability assessment of optical packet switching for metro networks

Optical packet switching (OPS) has been proposed as a strong candidate for future metro networks. This paper assesses the viability of an OPS-based ring architecture as proposed within the research project DAVID (Data And Voice Integration on DWDM), funded by the European Commission through the Information Society Technologies (IST) framework. Its feasibility is discussed from a physical-layer point of view, and its limitations in size are explored. Through dimensioning studies, we show that the proposed OPS architecture is competitive with respect to alternative metropolitan area network (MAN) approaches, including synchronous digital hierarchy, resilient packet rings (RPR), and star-based Ethernet. Finally, the proposed OPS architectures are discussed from a logical performance point of view, and a high-quality scheduling algorithm to control the packet-switching operations in the rings is explained

Survivable mesh-network design & optimization to support multiple QoP service classes

Every second, vast amounts of data are transferred over communication systems around the world, and as a result, the demands on optical infrastructures are extending beyond the traditional, ring-based architecture. The range of content and services available from the Internet is increasing, and network operations are constantly under pressure to expand their optical networks in order to keep pace with the ever increasing demand for higher speed and more reliable links

Resource Management in Survivable Multi-Granular Optical Networks

The last decade witnessed a wild growth of the Internet traffic, promoted by bandwidth-hungry applications such as Youtube, P2P, and VoIP. This explosive increase is expected to proceed with an annual rate of 34% in the near future, which leads to a huge challenge to the Internet infrastructure. One foremost solution to this problem is advancing the optical networking and switching, by which abundant bandwidth can be provided in an energy-efficient manner. For instance, with Wavelength Division Multiplexing (WDM) technology, each fiber can carry a mass of wavelengths with bandwidth up to 100 Gbits/s or higher. To keep up with the traffic explosion, however, simply scaling the number of fibers and/or wavelengths per fiber results in the scalability issue in WDM networks. One major motivation of this dissertation is to address this issue in WDM networks with the idea of waveband switching (WBS). This work includes the author\u27s study on multiple aspects of waveband switching: how to address dynamic user demand, how to accommodate static user demand, and how to achieve a survivable WBS network. When combined together, the proposed approaches form a framework that enables an efficient WBS-based Internet in the near future or the middle term. As a long-term solution for the Internet backbone, the Spectrum Sliced Elastic Optical Path (SLICE) Networks recently attract significant interests. SLICE aims to provide abundant bandwidth by managing the spectrum resources as orthogonal sub-carriers, a finer granular than wavelengths of WDM networks. Another important component of this dissertation is the author\u27s timely study on this new frontier: particulary, how to efficiency accommodate the user demand in SLICE networks. We refer to the overall study as the resource management in multi-granular optical networks. In WBS networks, the multi-granularity includes the fiber, waveband, and wavelength. While in SLICE networks, the traffic granularity refers to the fiber, and the variety of the demand size (in terms of number of sub-carriers)

Survivability stategies in all optical networks.

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.Thesis (M.Sc.)-University of KwaZulu-Natal, 2006.Recent advances in fiber optics technology have enabled extremely high-speed transport of different forms of data, on multiple wavelengths of an optical fiber, using Dense Wavelength Division Multiplexing (DWDM). It has now become possible to deploy high-speed, multi-service networks using DWDM technology. As the amount of traffic carried has increased, any single failure can be catastrophic. Survivability becomes indispensable in such networks. Therefore, it is imperative to design networks that can quickly and efficiently recover from failures. Most research to date in survivable optical network design and operation focuses on single link failures, however, the occurrence of multiple-link failures are not uncommon in networks today. Multi-link failure scenarios can arise out of two common situations. First, an arbitrary link may fail in the network, and before that link can be repaired, another link fails, thus creating a multi-link failure sequence. Secondly, it might happen in practice that two distinct physical links may be routed via the same common duct or physical channel. A failure at that shared physical location creates a logical multiple-link failure. In this dissertation, we conduct an intensive study of mechanisms for achieving survivability in optical networks. From the many mechanisms presented in the literature the focus of this work was on protection as a mechanism of survivability. In particular four protection schemes were simulated and their results analyzed to ascertain which protection scheme achieves the best survivability in terms of number of wavelengths recovered for a specific failure scenario. A model network was chosen and the protection schemes were evaluated for both single and multiple link and node failures. As an indicator of the performance of these protection schemes over a period of time average service availability and average loss in traffic for each protection scheme was also simulated. Further simulations were conducted to observe the percentage link and node utilization of each scheme hence allowing us to determine the strain each protection scheme places on network resources when traffic in the network increases. Finally based on these simulation results, recommendations of which protection scheme and under what failure conditions they should be used are made.Recent advances in fiber optics technology have enabled extremely high-speed transpor

Contribution à l'amélioration de l'efficacité des réseaux IP sur WDM en évaluant et en dépassant les limites du dimensionnement multicouche

The traffic passing through core networks grows by nearly 25% each year. To bring the costs under control, the different network layers of the network should work together to include more and more parameters during the network planning phase. This is called “multilayer network planning”. We study the multilayer network planning of static networks composed of two circuit switched layers (typically IP-over-WDM). We propose a semi-analytical model explaining the behavior of algorithms responsible for aggregation and routing in both layers. This theory allows comparing multilayer planning algorithms between them, but also explaining and enhancing their efficiency. We then describe the impact of the optical reach constraint in WDM networks on the results of a multilayer planning algorithm. Finally, we explain how these results apply to the design of future networks (dynamic and with heterogeneous optical layers)La quantité de données devant être transportée via les réseaux de cœur croit de près de 25% par an. Pour maîtriser les coûts, les différentes couches du réseau doivent mettre des informations en commun pour inclure de plus en plus de paramètres lors du dimensionnement du réseau. Cela s’appelle « dimensionnement multicouche ». Nous étudions le dimensionnement multicouche de réseaux statiques composés de deux couches utilisant la commutation en mode circuit (typiquement IP-sur-WDM). Nous proposons un modèle semi-analytique expliquant le comportement des algorithmes responsables de l’agrégation et du routage dans les deux couches. Ce cadre théorique permet de comparer les algorithmes de dimensionnement multicouche entre eux, mais aussi d’expliquer et d’améliorer leur efficience. Nous décrivons ensuite comment la contrainte de portée optique affecte les résultats d’un algorithme de dimensionnement multicouche. Enfin, nous expliquons comment ces résultats s'appliquent au dimensionnement des réseaux de nouvelle génération (dynamiques et hétérogènes en capacité optique

SLA Formulation for Squeezed Protection in Elastic Optical Networks Considering the Modulation Format

In spectrum-sliced elastic optical path networks (SLICE), the lightpath bandwidth is variable, and the virtual topology overlay on a physical topology shall be designed to optimize the spectrum utilization. Under static traffic, SLICE networks are typically designed through a mixed integer linear programming (MILP) with the aim of minimizing the spectrum utilization. In this paper, a new MILP formulation for protection in SLICE networks is proposed, which uses the concept of bandwidth squeezing and grooming to guarantee a minimum agreed bandwidth for each source–destination pair in the surviving bandwidth. The route for each demand on the physical topology is determined by balance equations together with physical layer constraints in the formulation, so that no pre-calculated routes are required and the modulation format of each established lightpath may be chosen with enough quality of transmission and to save network spectrum. Therefore, the proposed formulation jointly solves the virtual topology design and physical topology design problems. The first results evaluate the effectiveness of the MILP formulation for two small networks when connections are under different service-level agreement (SLA) requirements and are provisioned by an appropriate protection scheme and different modulation formats. Due to the NP-hard nature of the proposed MILP formulation, a heuristic algorithm for moderately large networks is also proposed. Case studies are carried out to analyze the basic properties of the formulation and the performance of the proposed heuristic. With the proposed formulation, it is possible to identify the configurations that ensure minimum spectrum occupation with different kinds of protection for each lightpath. Different kinds of modulation formats are considered and contrasted to the benchmark case of a single modulation format and using the same kind of protection for all lightpaths

Survivability schemes for dynamic traffic in optical networks

Ph.DDOCTOR OF PHILOSOPH

Efficient Management of Flexible Functional Splits in 5G Second Phase Networks

The fifth mobile network generation (5G), which offers better data speeds, reduced latency, and a huge number of network connections, promises to improve the performance of the cellular network in practically every way available. A portion of the network operations are deployed in a centralized unit in the 5G radio access network (RAN) partially centralized design. By centralizing these functions, operational expenses are decreased and coordinating strategies are made possible. To link centralized units (CU) and distributed units (DU), and the DU to remote radio units (RRU), both the midhaul and fronthaul networks must have higher capacity. The necessary fronthaul capacity is also influenced by the fluctuating instantaneous user traffic. Consequently, the 5G RAN must be able to dynamically change its centralization level to the user traffic to maximize its performance. To try to relieve this fronthaul capacity it has been considered a more flexible distribution between the base band unit (BBU) (or CU and DU if enhanced common public radio interface (eCPRI) is considered) and the RRU. It may be challenging to provide high-speed data services in crowded areas, particularly when there is imperfect coverage or significant interference. Because of this, the macrocell deployment is insufficient. This problem for outdoor users could be resolved by the introduction of low-power nodes with a limited coverage area. In this context, this MSc dissertation explores, in an urban micro cell scenario model A (UMi_A) for three frequency bands (2.6 GHz, 3.5 GHz, and 5.62 GHz), the highest data rate achievable when a numerology zero is used. For this, it was necessary the implementation of the UMi_A in the 5G-air-simulator. Allowing the determination of the saturation level using the results for the packet loss ratio (PLR=2%). By assuming Open RAN (O-RAN) and functional splitting, the performance of two schedulers in terms of quality-of-service (QoS) were also studied. The QoS-aware modified largest weighted delay first (M-LWDF) scheduler and the QoS-unaware proportional fair (PF) scheduler. PLR was evaluated for both schedulers, whilst analyzing the impact of break point distance while changing the frequency band. The costs, revenues, profit in percentage terms, and other metrics were also estimated for the PF and M-LWDF schedulers when used video (VID) and video plus best effort (VID+BE), with or without consideration of the functional splits 7.2 and 6, for the three frequency bands. One concluded that the profit in percentage terms with functional split option 7.2 applied is always slightly higher than with functional split option 6. It reaches a maximum profit of 366.92% in the case of the M-LWDF scheduler, and 305.51% in the case of the PF scheduler, at a cell radius of 0.4 km for the 2.6 GHz frequency band, considering a price of the traffic of 0.0002 €/min.A quinta geração de redes móveis (5G), oferece ritmos de transmissão melhorados, atraso extremo-a-extremo reduzido, e um vasto número de ligações de rede. A 5G promete melhorar o desempenho das redes celulares em praticamente todos os aspectos relevantes. Uma parte da operação da rede é colocada numa unidade centralizada na rede de acesso de rádio (RAN) 5G com dimensionamento parcialmente centralizado. Ao centralizar estas funções, os custos operacionais decrescem, viabilizando-se as estratégias de coordenação. Para ligar as unidades centralizadas e unidades distribuídas, e por sua vez, unidades distribuidas e unidades de rádio remotas, ambos os midhaul e fronthaul devem ter uma capacidade mais elevada. A capacidade da fronthaul necessária é também influenciada pela flutuação do tráfego instantâneo dos utilizadores. Consequentemente, a RAN 5G deve ser capaz de alterar dinamicamente o seu nível de centralização para o tráfego de utilizadores, com objetivo de maximizar o seu desempenho. Para tentar aliviar o aumento da capacidade suportada pelo fronthaul, tem sido considerada uma distribuição mais flexível entre a unidade de banda base, BBU (ou unidade central e unidade distribuída se a interface de rádio pública comum melhorada, eCPRI, for considerada), e a unidade de rádio remota, RRU. Em áreas densamente povoadas, pode ser um desafio fornecer serviços de dados de elevada velocidade, particularmente quando existe uma cobertura deficiente ou interferência significativa. Por este motivo, o desenvolvimento de macrocélulas pode ser insuficiente, mas este problema para utilizadores em ambiente de exterior pode ser mitigado com a introdução de nós de potência reduzida com uma área de cobertura limitada. Neste contexto, esta dissertação de mestrado explora, num cenário urbano de microcélulas caracterizado pelo modelo A (UMi_A) para três bandas de frequência (2.6 GHz, 3.5 GHz, e 5.62 GHz), o débito binário máximo que se pode alcançar quando se utiliza numerologia zero. Para tal, foi necessária a implementação do UMi_A no 5G - air - simulator. Determinou-se o nivel de saturação, considerandose os resultados para a taxa de perda de pacotes (PLR=2%). Estudou-se o desempenho de dois escalonadores de pacotes em termos de qualidade de serviço (QoS), assumindo-se o OpenRAN (O-RAN) e as divisões funcionais (functionalsplitting). Um dos escalonadores é ciente da QoS, e é de atraso máximo-superior ponderado primeiro (M-LWDF), enquanto que o outro não é ciente da QoS, e é de justiça proporcional (PF). Avaliou-se o PLR para ambos os escalonadores de pacotes, estudando-se o impacto da distância de ponto de quebra (breakpointdistance), variando-se a banda de frequências. Foram também estimados os custos, proveitos, o lucro (em percentagem), e outras metricas, para os escalonadores PF e M-LWDF, considerando o vídeo (VID) e vídeo mais besteffort (VID+BE) como aplicações, com ou sem a consideração das divisões funcionais 7.2 e 6, para as três bandas de frequência. Concluiu-se que o lucro em termos percentuais, com a escolha da opção de divisão funcional 7.2, é sempre ligeiramente mais elevado do que com a opção de divisão funcional 6. Atingese um lucro máximo de 366,92% no caso do escalonador M-LWDF, e de 305,51% no caso do escalonador PF, para um raio de célula de 0,4 km, para a banda de frequência de 2,6 GHz, considerando-se um preço do tráfego de 0,0002 €/min