Revenue Maximization in an Optical Router Node Using Multiple Wavelengths

In this paper, an optical router node with multiple wavelengths is considered. We introduce revenue for successful transmission and study the ensuing revenue maximization problem. We present an efficient and accurate heuristic procedure for solving the NP-hard revenue maximization problem and investigate the advantage offered by having multiple wavelengths

Destination-based Routing and Circuit Allocation for Future Traffic Growth

Internet traffic continues to grow relentlessly, driven largely by increasingly high- \\ resolution video streaming, the increasing adoption of cloud computing, the emergence of 5G networks, and the ever-growing reach of social media and social networks. Existing networks use packet switching to route packets on a hop-by-hop basis from the source to the destination. However, they suffer from two shortcomings. First, in existing networks, packets are routed along a fixed shortest path using the Open Shortest Path First (OSPF) protocol or obliviously load-balanced across equal-cost paths using the Equal-Cost Multi-Path (ECMP) protocol. These routing protocols do not fully utilize the network capacity because they do not adapt to network congestions in their routing decisions. Second, although studies have shown that the majority of packets processed by Internet routers are pass-through traffic, packets nonetheless have to be queued and routed at every hop in existing networks, which unnecessarily adds substantial delays and processing costs.In this thesis, we present two new approaches to overcome these shortcomings. First, we propose new backpressure-based routing algorithms which use only shortest-path routes when they are sufficient to accommodate the given traffic load, but will incrementally expand routing choices as needed to accommodate increasing traffic loads. This avoids the poor delay performance inherent in backpressure-based routing algorithms where packets may take long detours under light or moderate loads, and still retains the notable advantage, the network-wide optimal throughput, because packets are adaptively routed along less congested paths.Second, we propose a unified packet and circuit switched network in which the underlying optical transport is used to circuit-switch pass-through traffic by means of pre-established circuits. This avoids unnecessary packet queuing delays and processing costs at each hop. We propose a novel convex optimization framework based on a new destination-based multicommodity flow formulation for the allocation of circuits in such unified networks

Energy Efficient Core Networks with Clouds

The popularity of cloud based applications stemming from the high volume of connected mobile devices has led to a huge increase in Internet traffic. In order to enable easy access to cloud applications, infrastructure providers have invested in geographically distributed databases and servers. However, intelligent and energy efficient high capacity transport networks with near ubiquitous connectivity are needed to adequately and sustainably serve these requirements. In this thesis, network virtualisation has been identified as a potential networking paradigm that can contribute to network agility and energy efficiency improvements in core networks with clouds. The work first introduces a new virtual network embedding core network architecture with clouds and a compute and bandwidth resource provisioning mechanism aimed at reducing power consumption in core networks and data centres. Further, quality of service measures in compute and bandwidth resource provisioning such as delay and customer location have been investigated and their impact on energy efficiency established. Data centre location optimisation for energy efficiency in virtual network embedding infrastructure has been investigated by developing a MILP model that selects optimal data centre locations in the core network. The work also introduces an optical OFDM based physical layer in virtual network embedding to optimise power consumption and optical spectrum utilization. In addition, virtual network embedding schemes aimed at profit maximization for cloud infrastructure providers as well greenhouse gas emission reduction in cloud infrastructure networks have been investigated. GreenTouch, a consortium of industrial and academic experts on energy efficiency in ICTs, has adopted the work in this thesis as one of the measures of improving energy efficiency in core networks

Study, evaluation and contributions to new algorithms for the embedding problem in a network virtualization environment

Network virtualization is recognized as an enabling technology for the future Internet. It aims to overcome the resistance of the current Internet to architectural change and to enable a new business model decoupling the network services from the underlying infrastructure. The problem of embedding virtual networks in a substrate network is the main resource allocation challenge in network virtualization and is usually referred to as the Virtual Network Embedding (VNE) problem. VNE deals with the allocation of virtual resources both in nodes and links. Therefore, it can be divided into two sub-problems: Virtual Node Mapping where virtual nodes have to be allocated in physical nodes and Virtual Link Mapping where virtual links connecting these virtual nodes have to be mapped to paths connecting the corresponding nodes in the substrate network. Application of network virtualization relies on algorithms that can instantiate virtualized networks on a substrate infrastructure, optimizing the layout for service-relevant metrics. This class of algorithms is commonly known as VNE algorithms. This thesis proposes a set of contributions to solve the research challenges of the VNE that have not been tackled by the research community. To do that, it performs a deep and comprehensive survey of virtual network embedding. The first research challenge identified is the lack of proposals to solve the virtual link mapping stage of VNE using single path in the physical network. As this problem is NP-hard, existing proposals solve it using well known shortest path algorithms that limit the mapping considering just one constraint. This thesis proposes the use of a mathematical multi-constraint routing framework called paths algebra to solve the virtual link mapping stage. Besides, the thesis introduces a new demand caused by virtual link demands into physical nodes acting as intermediate (hidden) hops in a path of the physical network. Most of the current VNE approaches are centralized. They suffer of scalability issues and provide a single point of failure. In addition, they are not able to embed virtual network requests arriving at the same time in parallel. To solve this challenge, this thesis proposes a distributed, parallel and universal virtual network embedding framework. The proposed framework can be used to run any existing embedding algorithm in a distributed way. Thereby, computational load for embedding multiple virtual networks is spread across the substrate network Energy efficiency is one of the main challenges in future networking environments. Network virtualization can be used to tackle this problem by sharing hardware, instead of requiring dedicated hardware for each instance. Until now, VNE algorithms do not consider energy as a factor for the mapping. This thesis introduces the energy aware VNE where the main objective is to switch off as many network nodes and interfaces as possible by allocating the virtual demands to a consolidated subset of active physical networking equipment. To evaluate and validate the aforementioned VNE proposals, this thesis helped in the development of a software framework called ALgorithms for Embedding VIrtual Networks (ALEVIN). ALEVIN allows to easily implement, evaluate and compare different VNE algorithms according to a set of metrics, which evaluate the algorithms and compute their results on a given scenario for arbitrary parameters

가상 네트워크의 자원 할당, 가격 결정 및 고장 관리

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2013. 8. 서승우.네트워크 가상화는 물리적 네트워크의 공유 자원들을 복수 개의 가상 네트워크들에 동적으로 할당할 수 있게 해주는 기술이다. 자원 할당의 유연성과 가상 네트워크들 사이의 독립성 때문에, 네트워크 가상화는 네트워크 테스트베드를 설계하기 위한 기반 기술로써 주로 활용되어 왔을 뿐만 아니라, 인터넷의 다양화를 지원하기 위한 비용 효율 높은 해결책으로써 여겨지기 시작했다. 서비스에 따라 계층화된 인터넷을 설계하기 위한 하나의 수단으로써, 네트워크 가상화는 여전히 해결해야 할 많은 도전 과제들을 가지고 있다. 이 학위 논문은 가상 네트워크 환경에서 중요한 몇 가지 새로운 연구 주제들을 제시하고, 그에 대한 효과적인 해법들을 제안한다. 첫 번째로, 가상 네트워크의 다양한 QoS 요구사항을 만족시킬 수 있는 네트워크 최적 분할 방법을 제안한다. QoS와 대역폭 제한 조건을 고려하여 가상 네트워크 분할 문제를 최적화 문제로 모형화하고, 문제의 구조적 복잡성을 해결하기 위해 최단 경로 라우팅에 기반한 휴리스틱을 제안한다. 실제 인터넷 환경을 고려한 대규모 실험을 통해, 제안한 휴리스틱의 효율성과 확장성을 입증한다. 다음으로, 가상 네트워크에서 차등 접속 서비스를 위한 경제성 분석 모델을 제시한다. 먼저 사용자 가입 변동 모형이 한 값으로 수렴하기 위한 충분 조건을 유도하고, 이러한 조건 하에서 인터넷 서비스 제공자의 수익을 최대화할 수 있는 최적의 가격 결정 방법 및 대역폭 분할 방법을 찾는다. 수치 실험을 통해, 적절한 가격 결정과 대역폭 분할이 이루어진다는 가정 하에서 차등화 서비스가 단일 서비스보다 더 높은 수익성을 나타낼 수 있음을 증명한다. 마지막으로, 가상 네트워크 간 트래픽 전환을 통한 빠르고 효과적인 고장 회복 기술을 개발한다. 가상 네트워크의 구조적 특성을 활용한 고장 회복 기술을 이용하면, 모든 링크에 대한 백업 경로가 항상 존재하도록 미리 토폴로지를 설계해야 할 필요가 없고, 각 라우터에서 그 경로들에 대한 계산을 미리 해 놓을 필요가 없다. 그럼에도 불구하고, 제안한 고장 회복 방법은 기존의 기술들과 같은 좋은 성능을 보인다. 이 학위 논문은 가상 네트워크를 기반으로 하는 인터넷 환경에서 발생할 수 있는 중요한 문제들을 다루고자 한다. 이 논문에서 제안하는 분석 모델 및 실험 결과들은 현재 인터넷의 한계를 극복하고, 미래 인터넷 아키텍처를 설계하기 위한 유용한 지침을 제공할 것이다.Network virtualization is an emerging technology that enables the dynamic partitioning of a shared physical network infrastructure into multiple virtual networks. Because of its flexibility in resource allocation and independency among virtual networks, the network virtualization technology has not only been mainly deployed to build a testbed network, but also has come to be regarded as a cost-effective solution for diversifying the Internet. As a means of building the multi-layered Internet, network virtualization still faces a number of challenging issues that need to be addressed. This dissertation deals with several important research topics and provides effective solutions in network virtualization environment. First, I focus on the optimal partitioning of finite substrate resources for satisfying the diverse QoS requirements of virtual networks. I formulate virtual network partitioning problem as a mixed integer multi-commodity flow problem. Then, to tackle the structural complexity of the problem, I propose a simple heuristic based on shortest path routing algorithm. By conducting large-scale network experiments, I verify the efficiency and scalability of the heuristic. Next, I propose an economic model for tiered access service in virtual networks in order to remedy the deficiency of the existing tiered service schemes. I first derive a sufficient condition for stability of user subscription dynamics, and find the optimal pricing and capacity partitioning by addressing the revenue maximization problem of the tiered access service in a network virtualization environment. Numerical results show that the tiered service can be more profitable than the non-tiered service under proper pricing and capacity partitioning conditions. Last, I develop a fast and effective failure recovery mechanism through inter-virtual network traffic switching in virtual networks. The proposed failure recovery mechanism neither has topological constraints for the existence of backup paths, nor requires the pre-computation of them, but nevertheless guarantees as fast recovery as the existing failure recovery methods. This dissertation aims to address important issues in the virtual network-based Internet. I believe that the analysis and results in this dissertation will provide useful guidelines to improve the Internet.1 Introduction 1.1 Background and Motivation 1.2 Contributions and Outline of the Dissertation 2 Effective Partitioning for Service Level Differentiation in Virtual Networks 2.1 Introduction 2.2 Related Work 2.3 Model and Assumption 2.3.1 Business Model 2.3.2 Network Model 2.3.3 Traffic Demands 2.3.4 QoS Metric 2.4 Formulation 2.4.1 Objective 2.4.2 Substrate Partitioning Problem 2.4.3 Decomposition 2.5 Heuristic 2.6 Evaluation 2.6.1 Small Network Experiment 2.6.2 Large Network Experiment 2.7 Summary 3 Optimal Pricing and Capacity Partitioning for Tiered Access Service in Virtual Networks 3.1 Introduction 3.2 Motivating Example 3.3 A Tiered Service Model 3.3.1 Network Virtualization Environment 3.3.2 Effective Access Rate 3.3.3 Valuation Parameter and User Utility 3.3.4 User Subscription and the ISP Revenue 3.4 Non-tiered Service Analysis 3.4.1 User Subscription Dynamics 3.4.2 Optimal Pricing for Maximizing the ISP Revenue 3.5 Tiered Service Analysis 3.5.1 User Subscription Dynamics 3.5.2 Convergence of the User Subscription Dynamics 3.5.3 Optimal Pricing for Maximizing the ISP Revenue 3.6 Numerical Results 3.6.1 Non-tiered Service Example 3.6.2 Tiered Service Example 3.7 Related Work and Discussion 3.8 Summary 4 Inter-Virtual Network Traffic Switching for Fast Failure Recovery 4.1 Introduction 4.2 Background 4.3 Preliminaries 4.3.1 Virtual Network Model 4.3.2 Design Goals 4.3.3 Business Models and Switching Policy Agreement 4.3.4 Other Considerations 4.4 Failure Recovery based on Traffic Switching 4.4.1 Inter-VN Traffic Switching 4.4.2 Failure Recovery Process 4.5 Numerical Analysis 4.5.1 Delay 4.5.2 Congestion probability 4.6 Summary 5 Conclusion A Proofs of Lemmas A.1 Proof of Lemma 2 A.2 Proof of Lemma 3Docto

Dimensionnement et optimisation des réseaux de collecte sans fil

The main work of this thesis focuses on the wireless backhaul networks. We studied different optimization problems in such networks that represent real challenges for industrial sector.The first issue addressed focuses on the capacity allocation on the links at minimum cost. It was solved by a linear programming approach with column generation. Our method solves the problems on large size networks. We then studied the problem of network infrastructure sharing between virtual operators. The objective is to maximize the revenue of the operator of the physical infrastructure while satisfying the quality of service constraints of virtual operators customers of the network. In this context, we proposed a robust model using mixed integer linear programming. In the following problem, we proposed a robust energy-aware routing solution for the network operators to reduce their energy consumption. Our solution was formulated using a mixed integer linear program. We also proposed heuristics to find efficient solutions for large networks. The last work of this thesis focuses on cognitive radio networks and more specifi- cally on the problem of bandwidth sharing. We formalized it using a linear program with a different approach to robust optimization. We based our solution on the 2-stage linear robust method.L’essentiel des travaux de cette thèse porte sur les réseaux de collectes de données sans fil. Nous avons étudié différents problèmes d’optimisation dans ces réseaux qui représentent de vrais challenges pour les industriels du secteur. Le premier problème porte sur l’allocation de capacités sur les liens à coût minimum. Il a été résolu par une approche de programmation linéaire avec génération de colonnes. Notre modèle permet de résoudre des problèmes de grandes tailles. Nous avons ensuite étudié le problème du partage d’infrastructure réseau entre opérateurs virtuels avec comme objectif de maximiser les revenus de l’opérateur de l’infrastructure physique tout en satisfaisant les demandes et les contraintes de qualité de service des opérateurs virtuels clients du réseau. Dans ce contexte, nous avons proposé une formulation robuste du problème en programmation linéaire en nombres entiers mixte. Un autre point de dépenses dans ce type de réseau est la consommation d’énergie. Nous avons proposé une solution robuste, de routage basée sur la consommation d’énergie du réseau. Notre solution a été formulée en utilisant un programme linéaire en nombre entiers mixte. Nous avons aussi proposé des heuristiques afin de trouver assez rapidement des solutions pour de grandes instances. Le dernier travail de cette thèse porte sur les réseaux radio cognitifs et plus précisément sur le problème de partage de bande passante. Nous l’avons formalisé en utilisant un programme linéaire mais avec une autre approche d’optimisation robuste. Nous utilisons la méthode d'optimisation robuste à 2 niveaux pour le résoudre

Characterization, design and re-optimization on multi-layer optical networks

L'augment de volum de tràfic IP provocat per l'increment de serveis multimèdia com HDTV o vídeo conferència planteja nous reptes als operadors de xarxa per tal de proveir transmissió de dades eficient. Tot i que les xarxes mallades amb multiplexació per divisió de longitud d'ona (DWDM) suporten connexions òptiques de gran velocitat, aquestes xarxes manquen de flexibilitat per suportar tràfic d’inferior granularitat, fet que provoca un pobre ús d'ample de banda. Per fer front al transport d'aquest tràfic heterogeni, les xarxes multicapa representen la millor solució. Les xarxes òptiques multicapa permeten optimitzar la capacitat mitjançant l'empaquetament de connexions de baixa velocitat dins de connexions òptiques de gran velocitat. Durant aquesta operació, es crea i modifica constantment una topologia virtual dinàmica gràcies al pla de control responsable d’aquestes operacions. Donada aquesta dinamicitat, un ús sub-òptim de recursos pot existir a la xarxa en un moment donat. En aquest context, una re-optimizació periòdica dels recursos utilitzats pot ser aplicada, millorant així l'ús de recursos. Aquesta tesi està dedicada a la caracterització, planificació, i re-optimització de xarxes òptiques multicapa de nova generació des d’un punt de vista unificat incloent optimització als nivells de capa física, capa òptica, capa virtual i pla de control. Concretament s'han desenvolupat models estadístics i de programació matemàtica i meta-heurístiques. Aquest objectiu principal s'ha assolit mitjançant cinc objectius concrets cobrint diversos temes oberts de recerca. En primer lloc, proposem una metodologia estadística per millorar el càlcul del factor Q en problemes d'assignació de ruta i longitud d'ona considerant interaccions físiques (IA-RWA). Amb aquest objectiu, proposem dos models estadístics per computar l'efecte XPM (el coll d'ampolla en termes de computació i complexitat) per problemes IA-RWA, demostrant la precisió d’ambdós models en el càlcul del factor Q en escenaris reals de tràfic. En segon lloc i fixant-nos a la capa òptica, presentem un nou particionament del conjunt de longituds d'ona que permet maximitzar, respecte el cas habitual, la quantitat de tràfic extra proveït en entorns de protecció compartida. Concretament, definim diversos models estadístics per estimar la quantitat de tràfic donat un grau de servei objectiu, i diferents models de planificació de xarxa amb l'objectiu de maximitzar els ingressos previstos i el valor actual net de la xarxa. Després de resoldre aquests problemes per xarxes reals, concloem que la nostra proposta maximitza ambdós objectius. En tercer lloc, afrontem el disseny de xarxes multicapa robustes davant de fallida simple a la capa IP/MPLS i als enllaços de fibra. Per resoldre aquest problema eficientment, proposem un enfocament basat en sobre-dimensionar l'equipament de la capa IP/MPLS i recuperar la connectivitat i el comparem amb la solució convencional basada en duplicar la capa IP/MPLS. Després de comparar solucions mitjançant models ILP i heurístiques, concloem que la nostra solució permet obtenir un estalvi significatiu en termes de costos de desplegament. Com a quart objectiu, introduïm un mecanisme adaptatiu per reduir l'ús de ports opto-electrònics (O/E) en xarxes multicapa sota escenaris de tràfic dinàmic. Una formulació ILP i diverses heurístiques són desenvolupades per resoldre aquest problema, que permet reduir significativament l’ús de ports O/E en temps molt curts. Finalment, adrecem el problema de disseny resilient del pla de control GMPLS. Després de proposar un nou model analític per quantificar la resiliència en topologies mallades de pla de control, usem aquest model per proposar un problema de disseny de pla de control. Proposem un procediment iteratiu lineal i una heurística i els usem per resoldre instàncies reals, arribant a la conclusió que es pot reduir significativament la quantitat d'enllaços del pla de control sense afectar la qualitat de servei a la xarxa.The explosion of IP traffic due to the increase of IP-based multimedia services such as HDTV or video conferencing poses new challenges to network operators to provide a cost-effective data transmission. Although Dense Wavelength Division Multiplexing (DWDM) meshed transport networks support high-speed optical connections, these networks lack the flexibility to support sub-wavelength traffic leading to poor bandwidth usage. To cope with the transport of that huge and heterogeneous amount of traffic, multilayer networks represent the most accepted architectural solution. Multilayer optical networks allow optimizing network capacity by means of packing several low-speed traffic streams into higher-speed optical connections (lightpaths). During this operation, a dynamic virtual topology is created and modified the whole time thanks to a control plane responsible for the establishment, maintenance, and release of connections. Because of this dynamicity, a suboptimal allocation of resources may exist at any time. In this context, a periodically resource reallocation could be deployed in the network, thus improving network resource utilization. This thesis is devoted to the characterization, planning, and re-optimization of next-generation multilayer networks from an integral perspective including physical layer, optical layer, virtual layer, and control plane optimization. To this aim, statistical models, mathematical programming models and meta-heuristics are developed. More specifically, this main objective has been attained by developing five goals covering different open issues. First, we provide a statistical methodology to improve the computation of the Q-factor for impairment-aware routing and wavelength assignment problems (IA-RWA). To this aim we propose two statistical models to compute the Cross-Phase Modulation variance (which represents the bottleneck in terms of computation time and complexity) in off-line and on-line IA-RWA problems, proving the accuracy of both models when computing Q-factor values in real traffic scenarios. Second and moving to the optical layer, we present a new wavelength partitioning scheme that allows maximizing the amount of extra traffic provided in shared path protected environments compared with current solutions. Specifically, we define several statistical models to estimate the traffic intensity given a target grade of service, and different network planning problems for maximizing the expected revenues and net present value. After solving these problems for real networks, we conclude that our proposed scheme maximizes both revenues and NPV. Third, we tackle the design of survivable multilayer networks against single failures at the IP/MPLS layer and WSON links. To efficiently solve this problem, we propose a new approach based on over-dimensioning IP/MPLS devices and lightpath connectivity and recovery and we compare it against the conventional solution based on duplicating backbone IP/MPLS nodes. After evaluating both approaches by means of ILP models and heuristic algorithms, we conclude that our proposed approach leads to significant CAPEX savings. Fourth, we introduce an adaptive mechanism to reduce the usage of opto-electronic (O/E) ports of IP/MPLS-over-WSON multilayer networks in dynamic scenarios. A ILP formulation and several heuristics are developed to solve this problem, which allows significantly reducing the usage of O/E ports in very short running times. Finally, we address the design of resilient control plane topologies in GMPLS-enabled transport networks. After proposing a novel analytical model to quantify the resilience in mesh control plane topologies, we use this model to propose a problem to design the control plane topology. An iterative model and a heuristic are proposed and used to solve real instances, concluding that a significant reduction in the number of control plane links can be performed without affecting the quality of service of the network