Novel Approaches and Architecture for Survivable Optical Internet

Any unexpected disruption to WDM (Wavelength Division Multiplexing) based optical networks which carry data traffic at tera-bit per second may result in a huge loss to its end-users and the carrier itself. Thus survivability has been well-recognized as one of the most important objectives in the design of optical Internet. This thesis proposes a novel survivable routing architecture for the optical Internet. We focus on a number of key issues that are essential to achieve the desired service scenarios, including the tasks of (a) minimizing the total number of wavelengths used for establishing working and protection paths in WDM networks; (b) minimizing the number of affected working paths in case of a link failure; (c) handling large scale WDM mesh networks; and (d) supporting both Quality of Service (QoS) and best-effort based working lightpaths. To implement the above objectives, a novel path based shared protection framework namely Group Shared protection (GSP) is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy, and optimization is performed on these PGs. To the best of our knowledge this is the first work done in the area of group based WDM survivable routing approaches where not only the resource sharing is conducted among the PGs to achieve the best possible capacity efficiency, but also an integrated survivable routing framework is provided by incorporating the above objectives. Simulation results show the effectiveness of the proposed schemes

Novel Approaches and Architecture for Survivable Optical Internet

Any unexpected disruption to WDM (Wavelength Division Multiplexing) based optical networks which carry data traffic at tera-bit per second may result in a huge loss to its end-users and the carrier itself. Thus survivability has been well-recognized as one of the most important objectives in the design of optical Internet. This thesis proposes a novel survivable routing architecture for the optical Internet. We focus on a number of key issues that are essential to achieve the desired service scenarios, including the tasks of (a) minimizing the total number of wavelengths used for establishing working and protection paths in WDM networks; (b) minimizing the number of affected working paths in case of a link failure; (c) handling large scale WDM mesh networks; and (d) supporting both Quality of Service (QoS) and best-effort based working lightpaths. To implement the above objectives, a novel path based shared protection framework namely Group Shared protection (GSP) is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy, and optimization is performed on these PGs. To the best of our knowledge this is the first work done in the area of group based WDM survivable routing approaches where not only the resource sharing is conducted among the PGs to achieve the best possible capacity efficiency, but also an integrated survivable routing framework is provided by incorporating the above objectives. Simulation results show the effectiveness of the proposed schemes

Resilient Resource Allocation Schemes in Optical Networks

Recent studies show that deliberate malicious attacks performed by high-power sig- nals can put large amount of data under risk. We investigate the problem of sur- vivable optical networks resource provisioning scheme against malicious attacks, more specically crosstalk jamming attacks. These types of attacks may cause ser- vice disruption (or possibly service denial). We consider optical networks based on wavelength-division multiplexing (WDM) technology and two types of jamming at- tacks: in-band and out-of-band attacks. We propose an attack-aware routing and wavelength assignments (RWA) scheme to avoid or reduce the damaging effects of potential attacking signals on individual or multiple legitimate lightpaths travers- ing the same optical switches and links. An integer linear programs (ILPs) as well as heuristic approaches were proposed to solve the problem. We consider dynamic traffic where each demand is dened by its start time and a duration. Our results show that the proposed approaches were able to limit the vulnerability of lightpaths to jamming attacks. Recently, large-scale failures caused by natural disasters and/or deliberate at- tacks have left major parts of the networks damaged or disconnected. We also investigate the problem of disaster-aware WDM network resource provisioning in case of disasters. We propose an ILP and efficient heuristic to route the lightpaths in such a way that provides protection against disasters and minimize the network vi resources such as the number of wavelength links used in the network. Our models show that signicant resource savings can be achieved while accommodating users demands. In the last few years, optical networks using Space Division Multiplexing (SDM) has been proposed as a solution to the speed bottleneck anticipated in data center (DC) networks. To our knowledge the new challenges of designing such communica- tion systems have not been addressed yet. We propose an optimal approach to the problem of developing a path-protection scheme to handle communication requests in DC networks using elastic optical networking and space division multiplexing. We have formulated our problem as an ILP. We have also proposed a heuristic that can handle problems of practical size. Our simulations explore important features of our approach

A Survey on the Path Computation Element (PCE) Architecture

Quality of Service-enabled applications and services rely on Traffic Engineering-based (TE) Label Switched Paths (LSP) established in core networks and controlled by the GMPLS control plane. Path computation process is crucial to achieve the desired TE objective. Its actual effectiveness depends on a number of factors. Mechanisms utilized to update topology and TE information, as well as the latency between path computation and resource reservation, which is typically distributed, may affect path computation efficiency. Moreover, TE visibility is limited in many network scenarios, such as multi-layer, multi-domain and multi-carrier networks, and it may negatively impact resource utilization. The Internet Engineering Task Force (IETF) has promoted the Path Computation Element (PCE) architecture, proposing a dedicated network entity devoted to path computation process. The PCE represents a flexible instrument to overcome visibility and distributed provisioning inefficiencies. Communications between path computation clients (PCC) and PCEs, realized through the PCE Protocol (PCEP), also enable inter-PCE communications offering an attractive way to perform TE-based path computation among cooperating PCEs in multi-layer/domain scenarios, while preserving scalability and confidentiality. This survey presents the state-of-the-art on the PCE architecture for GMPLS-controlled networks carried out by research and standardization community. In this work, packet (i.e., MPLS-TE and MPLS-TP) and wavelength/spectrum (i.e., WSON and SSON) switching capabilities are the considered technological platforms, in which the PCE is shown to achieve a number of evident benefits

Disaster Resilient Optical Core Networks

During the past few years, the number of catastrophic disasters has increased and its impact sometimes incapacitates the infrastructures within a region. The communication network infrastructure is one of the affected systems during these events. Thus, building a resilient network backbone is essential due to the big role of networks during disaster recovery operations. In this thesis, the research efforts in building a disaster-resilient network are reviewed and open issues related to building disaster-resilient networks are discussed. Large size disasters not necessarily impact the communication networks, but instead it can stimulate events that cause network performance degradation. In this regard, two open challenges that arise after disasters are considered one is the short-term capacity exhaustion and the second is the power outage. First, the post-disaster traffic floods phenomena is considered. The impact of the traffic floods on the optical core network performance is studied. Five mitigation approaches are proposed to serve these floods and minimise the incurred blocking. The proposed approaches explore different technologies such as excess or overprovisioned capacity exploitation, traffic filtering, protection paths rerouting, rerouting all traffic and finally using the degrees of freedom offered by differentiated services. The mitigation approaches succeeded in reducing the disaster induced traffic blocking. Second, advance reservation provisioning in an energy-efficient approach is developed. Four scenarios are considered to minimise power consumption. The scenarios exploit the flexibility provided by the sliding-window advance reservation requests. This flexibility is studied through scheduling and rescheduling scenarios. The proposed scenarios succeeded in minimising the consumed power. Third, the sliding-window flexibility is exploited for the objective of minimising network blocking during post-disaster traffic floods. The scheduling and rescheduling scenarios are extended to overcome the capacity exhaustion and improve the network blocking. The proposed schemes minimised the incurred blocking during traffic floods by exploiting sliding window. Fourth, building blackout resilient networks is proposed. The network performance during power outages is evaluated. A remedy approach is suggested for maximising network lifetime during blackouts. The approach attempts to reduce the required backup power supply while minimising network outages due to limited energy production. The results show that the mitigation approach succeeds in keeping the network alive during a blackout while minimising the required backup power

Improving the connectivity resilience of a telecommunications network to multiple link failures through a third-party network

Currently, telecommunication networks are fully resilient, in terms of connectivity, to single link failures. On the other hand, multiple simultaneous link failures are becoming a concern to network operators, mainly due to malicious human activities. Full connectivity resilience to multiple link failures is too costly and other solutions must be envisaged. For a given maximum number of simultaneous link failures, the connectivity resilience metric adopted here is the minimum number of network node pairs that can still communicate for any set of failing links. In this work, the connectivity resilience to multiple link failures is improved by resorting to a third-party network for temporary additional connectivity (i.e., while the failing links are not reestablished). In such a solution, some nodes must be selected to act as gateway nodes between the two networks. For a given network topology and a given number of gateway nodes, the aim is to select the most appropriate gateway nodes so that the connectivity resilience is improved as much as possible. To address this problem, a Gateway Node Selection (GNS) algorithm is proposed where the most damaging sets of failing links are identified and, then, a set cover problem type is defined and solved to select the gateway nodes. The computational results demonstrate the effectiveness of the proposed GNS algorithm over two well-known network topologies.publishe

Mécanismes d'allocation de ressources et fiabilité dans les réseaux coeur de prochaines générations

Définitions et concepts de bases -- Éléments de problématique -- Objectifs de recherche -- Principales contributions -- Revue de littérature -- Modèles de services -- Routage avec Qualité de Service -- Ingénierie de traffic -- Contrôle d'admission avec Qualité de Service -- Fiabilité des réseaux -- A novel admission control mechanism in GMPLS- BASED IP over optical networks -- Problem statement -- Numerical results -- Joint routing and admission control problem under statistical delay and jitter constraints in MPLS networks -- Simulation results -- A survivable multicast routing mechanism in WDM optical networks -- Survivable routing under SRLG constraints -- GR-SMRS : Greedy heuristic for survivable multicast routing under SRLG constraints -- simulation results

Survivable Virtual Network Embedding in Transport Networks

Network Virtualization (NV) is perceived as an enabling technology for the future Internet and the 5th Generation (5G) of mobile networks. It is becoming increasingly difficult to keep up with emerging applications’ Quality of Service (QoS) requirements in an ossified Internet. NV addresses the current Internet’s ossification problem by allowing the co-existence of multiple Virtual Networks (VNs), each customized to a specific purpose on the shared Internet. NV also facilitates a new business model, namely, Network-as-a-Service (NaaS), which provides a separation between applications and services, and the networks supporting them. 5G mobile network operators have adopted the NaaS model to partition their physical network resources into multiple VNs (also called network slices) and lease them to service providers. Service providers use the leased VNs to offer customized services satisfying specific QoS requirements without any investment in deploying and managing a physical network infrastructure. The benefits of NV come at additional resource management challenges. A fundamental problem in NV is to efficiently map the virtual nodes and virtual links of a VN to physical nodes and paths, respectively, known as the Virtual Network Embedding (VNE) problem. A VNE that can survive physical resource failures is known as the survivable VNE (SVNE) problem, and has received significant attention recently. In this thesis, we address variants of the SVNE problem with different bandwidth and reliability requirements for transport networks. Specifically, the thesis includes four main contributions. First, a connectivity-aware VNE approach that ensures VN connectivity without bandwidth guarantee in the face of multiple link failures. Second, a joint spare capacity allocation and VNE scheme that provides bandwidth guarantee against link failures by augmenting VNs with necessary spare capacity. Third, a generalized recovery mechanism to re-embed the VNs that are impacted by a physical node failure. Fourth, a reliable VNE scheme with dedicated protection that allows tuning of available bandwidth of a VN during a physical link failure. We show the effectiveness of the proposed SVNE schemes through extensive simulations. We believe that the thesis can set the stage for further research specially in the area of automated failure management for next generation networks