As WDM results in an ever-increasing trend of traffic concentration, any failure on a single fiber-link or a single switching node will be catastrophic. Rapid restoration can recover the affected traffic so as to make the network more robust and reliable. The conventional restoration methods are designed mostly for reconfiguring the network topology; they are not immune from service interruption. In this thesis, an effective algorithm called backup-path-wavelength rearrangement scheme is proposed to reduce the connection blocking probability in an all-optical network. The proposed scheme performs wavelength retuning on the backup paths to improve the acceptance probability for new connection requests and introduce zero service interruption to the traffic in the network. The performance evaluation indicates that the connection blocking probability can be decreased greatly by the proposed scheme. The combination of BPWR and traffic grooming can efficiently alleviate the wavelength continuity constraint.

This thesis evaluates the performance of service differentiation with different class of services namely protection, reservation and the best effort services on the NxN meshed torus and the ring topology, which are established as survivable all&amp / #8208 / optical WDM networks. Blocking probabilities are measured as performance criteria and the effects of different number of wavelengths, different type of services and different topology size with wavelength selective lightpath allocation schemes are investigated by simulations with respect to increasing load on the topologies.

Fault management is a challenging task in all-optical wavelength division multiplexing (WDM) networks. However, fast fault localization for shared risk link groups (SRLGs) with multiple links is essential for building a fully survival and functional transparent all-optical mesh network. Monitoring trail (m-trail) technology is an effective approach to achieve the goal, whereby a set of m-trails are derived for unambiguous fault localization (UFL). However, an m-trail traverses through a link by utilizing a dedicated wavelength channel (WL), causing a significant amount of resource consumption. In addition, existing m-trail methods incur long and variable alarm dissemination delay. We introduce a novel framework of real-time fault localization in all-optical WDM mesh networks, called the monitoring-burst (m-burst), which aims at initiating a balanced trade-off between consumed monitoring resources and fault localization latency. The m-burst framework has a single monitoring node (MN) and requires one WL in each unidirectional link if the link is traversed by any m-trail. The MN launches short duration optical bursts periodically along each m-trail to probe the links of the m-trail. Bursts along different m-trails are kept non-overlapping through each unidirectional link by scheduling burst launching times from the MN and multiplexing multiple bursts, if any, traversing the link. Thus, the MN can unambiguously localize the failed links by identifying the lost bursts without incurring any alarm dissemination delay. We have proposed several novel m-trail allocation, burst launching time scheduling, and node switch fabric configuration schemes. Numerical results show that the schemes, when deployed in the m-burst framework, are able to localize single-link and multi-link SRLG faults unambiguously, with reasonable fault localization latency, by using at most one WL in each unidirectional link. To reduce the fault localization latency further, we also introduce a novel methodology called nested m-trails. At first, mesh networks are decomposed into cycles and trails. Each cycle (trail) is realized as an independent virtual ring (linear) network using a separate pair of WLs (one WL in each direction) in each undirected link traversed by the cycle (trail). Then, sets of m-trails, i.e., nested m-trails, derived in each virtual network are deployed independently in the m-burst framework for ring (linear) networks. As a result, the fault localization latency is reduced significantly. Moreover, the application of nested m-trails in adaptive probing also reduces the number of sequential probes significantly. Therefore, practical deployment of adaptive probing is now possible. However, the WL consumption of the nested m-trail technique is not limited by one WL per unidirectional link. Thus, further investigation is needed to reduce the WL consumption of the technique.

Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman’s Problem (CPP) solution and an adapted version of the Traveling Salesman’s Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of solutions for m-trail design problem of these models are proposed. The comparison between these models uses the expected survivability function which proved that these models are liable to be implemented in the new and existing PON/ RoF-PON systems. This dissertation is followed by recommendation of possible directions for future research in this area.

Este trabalho investiga a influência dos efeitos da mistura de quatro ondas (FWM -. Four- Wave Mixing) durante o estabelecimento de caminhos ópticos em uma rede GMPLS/DWDM (Generalized MultiProtocol Label Switching/Dense Wavelength Division Multiplexing). Para minimizar seus impactos e assim reduzir o bloqueio total da rede, são propostas estratégias por meio de extensões ao RSVP-TE (Resource Reservation Protocol-Traffic Engineering). A partir de uma plataforma de simulação que emula e integra a camada óptica e o Plano de Controle da arquitetura GMPLS, a solução proposta é validada. Os vários métodos de alocação de comprimentos de onda são avaliados e as contribuições na redução dos sinais interferentes quantificadas. Para minimizar o bloqueio na rede, uma nova classe de métodos de alocação, classificados como híbridos, é definida e seu desempenho é avaliado. O bloqueio da rede em função da variação de parâmetros que reforçam a eficiência da FWM, tais como a quantidade e espaçamento entre canais, é observado, confirmando a necessidade de métodos de alocação especialistas para gerenciamento do QoS (Quality of Service) óptico em cada caminho a ser estabelecido. Os resultados obtidos comprovam a eficiência da solução proposta e evidenciam a necessidade de um Plano de Controle GMPLS com acurada visibilidade das restrições da camada física, tanto os efeitos estáticos quanto às degradações associadas ao comportamento dinâmico da rede. / This work investigates the effects of the Four-Wave Mixing (FWM) during the lightpaths establishment in a GMPLS/DWDM (Generalized Multiprotocol Label Switching / Dense Wavelength Division Multiplexing) network. In order to minimize their impacts and thus reduce network blocking, strategies based on RSVP-TE (Resource Reservation Protocol- Traffic Engineering) extensions are proposed. The proposed solution is validated using a simulation platform that integrates and emulates the optical layer and the GMPLS Control Plane. The various wavelength allocation methods are evaluated and their contributions on the reduction of interfering signals are quantified. In order to minimize the network blocking, a new class of allocation methods (classified as hybrids) is defined and its performance is evaluated. The network blocking caused by the parameters that enhance the FWM efficiency, such as the number and spacing between channels, is also observed, confirming the need of specialized wavelength allocation methods for managing the optical QoS for each lightpath. The results obtained ascertain that the proposed solution is efficient and demonstrate the need for a GMPLS Control Plane endowed with an accurate visibility of the restrictions in the physical layer, concerning both static and dynamic effects.

Este trabalho investiga a influência dos efeitos da mistura de quatro ondas (FWM -. Four- Wave Mixing) durante o estabelecimento de caminhos ópticos em uma rede GMPLS/DWDM (Generalized MultiProtocol Label Switching/Dense Wavelength Division Multiplexing). Para minimizar seus impactos e assim reduzir o bloqueio total da rede, são propostas estratégias por meio de extensões ao RSVP-TE (Resource Reservation Protocol-Traffic Engineering). A partir de uma plataforma de simulação que emula e integra a camada óptica e o Plano de Controle da arquitetura GMPLS, a solução proposta é validada. Os vários métodos de alocação de comprimentos de onda são avaliados e as contribuições na redução dos sinais interferentes quantificadas. Para minimizar o bloqueio na rede, uma nova classe de métodos de alocação, classificados como híbridos, é definida e seu desempenho é avaliado. O bloqueio da rede em função da variação de parâmetros que reforçam a eficiência da FWM, tais como a quantidade e espaçamento entre canais, é observado, confirmando a necessidade de métodos de alocação especialistas para gerenciamento do QoS (Quality of Service) óptico em cada caminho a ser estabelecido. Os resultados obtidos comprovam a eficiência da solução proposta e evidenciam a necessidade de um Plano de Controle GMPLS com acurada visibilidade das restrições da camada física, tanto os efeitos estáticos quanto às degradações associadas ao comportamento dinâmico da rede. / This work investigates the effects of the Four-Wave Mixing (FWM) during the lightpaths establishment in a GMPLS/DWDM (Generalized Multiprotocol Label Switching / Dense Wavelength Division Multiplexing) network. In order to minimize their impacts and thus reduce network blocking, strategies based on RSVP-TE (Resource Reservation Protocol- Traffic Engineering) extensions are proposed. The proposed solution is validated using a simulation platform that integrates and emulates the optical layer and the GMPLS Control Plane. The various wavelength allocation methods are evaluated and their contributions on the reduction of interfering signals are quantified. In order to minimize the network blocking, a new class of allocation methods (classified as hybrids) is defined and its performance is evaluated. The network blocking caused by the parameters that enhance the FWM efficiency, such as the number and spacing between channels, is also observed, confirming the need of specialized wavelength allocation methods for managing the optical QoS for each lightpath. The results obtained ascertain that the proposed solution is efficient and demonstrate the need for a GMPLS Control Plane endowed with an accurate visibility of the restrictions in the physical layer, concerning both static and dynamic effects.

Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman’s Problem (CPP) solution and an adapted version of the Traveling Salesman’s Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of solutions for m-trail design problem of these models are proposed. The comparison between these models uses the expected survivability function which proved that these models are liable to be implemented in the new and existing PON/ RoF-PON systems. This dissertation is followed by recommendation of possible directions for future research in this area.

Fault localization is the process of realizing the true source of a failure from a set of collected failure notifications. Isolating failure recovery within the network optical domain is necessary to resolve alarm storm problems. The introduction of the monitoring trail (m-trail) has been proven to deliver better performance by employing monitoring resources in a form of optical trails - a monitoring framework that generalizes all the previously reported counterparts. In this dissertation, the m-trail design is explored and a focus is given to the analysis on using m-trails with established lightpaths to achieve fault localization. This process saves network resources by reducing the number of the m-trails required for fault localization and therefore the number of wavelengths used in the network. A novel approach based on Geographic Midpoint Technique, an adapted version of the Chinese Postman’s Problem (CPP) solution and an adapted version of the Traveling Salesman’s Problem (TSP) solution algorithms is introduced. The desirable features of network architectures and the enabling of innovative technologies for delivering future millimeter-waveband (mm-WB) Radio-over-Fiber (RoF) systems for wireless services integrated in a Dense Wavelength Division Multiplexing (DWDM) is proposed in this dissertation. For the conceptual illustration, a DWDM RoF system with channel spacing of 12.5 GHz is considered. The mm-WB Radio Frequency (RF) signal is obtained at each Optical Network Unit (ONU) by simultaneously using optical heterodyning photo detection between two optical carriers. The generated RF modulated signal has a frequency of 12.5 GHz. This RoF system is easy, cost-effective, resistant to laser phase noise and also reduces maintenance needs, in principle. A revision of related RoF network proposals and experiments is also included. A number of models for Passive Optical Networks (PON)/ RoF-PON that combine both innovative and existing ideas along with a number of solutions for m-trail design problem of these models are proposed. The comparison between these models uses the expected survivability function which proved that these models are liable to be implemented in the new and existing PON/ RoF-PON systems. This dissertation is followed by recommendation of possible directions for future research in this area.

This work develops an exact logical operation model to predict the performance of the all-optical shared-memory architecture (OSMA) class of packet switches and provides a means to obtain a reasonable approximation of OSMA switch performance within certain types of networks, including the Banyan family. All-optical packet switches have the potential to far exceed the bandwidth capability of their current electronic counterparts. However, all-optical switching technology is currently not mature. Consequently, all-optical switch fabrics and buffers are more constrained in size and can cost several orders of magnitude more than those of electronic switches. The use of shared-memory buffers and/or links with multiple parallel channels (channel grouping) have been suggested as ways to maximize switch performance with buffers of limited size. However, analysis of shared-memory switches is far more difficult than for other commonly used buffering strategies. Obtaining packet loss performance by simulation is often not a viable alternative to modeling if low loss rates or large networks are encountered. Published models of electronic shared-memory packet switches (ESMP) have primarily involved approximate models to allow analysis of switches with a large number of ports and/or buffer cells. Because most ESMP models become inaccurate for small switches, and OSMA switches, unlike ESMP switches, do not buffer packets unless contention occurs, existing ESMP models cannot be applied to OSMA switches. Previous models of OSMA switches were confined to isolated (non-networked), symmetric OSMA switches using channel grouping under random traffic. This work is far more general in that it also encompasses OSMA switches that (1) are subjected to bursty traffic and/or with input links that have arbitrary occupancy probability distributions, (2) are interconnected to form a network and (3) are asymmetric.

Optical WDM network is the suitable transport mechanism for ever increasing bandwidth intensive internet applications. The WDM technique transmits the data over several different wavelengths simultaneously through an opticalfiber and the switching is done at wavelength level. The connection between the source and destination is called the light path. Since the WDM network carries huge amount of tra c, any failure can cause massive data loss. Therefore protecting the network against failure is an important issue. Maintaining high level of service availability is an important aspect of service provider. To provide cost effective service, all-optical network is the suitable choice for the service provider. But in all optical network, the signals are forced to remain in optical domain from source to destination. In the firrst part of the thesis, we deal the physical layer impairments (PLIs) aware shared-path provisioning on a wavelength routed all-optical networks. As the signal travels longer distances, the quality of the signal gets degraded and the receiver may not be able to detect the optical signal properly. Our objective is to establish a light path for both the working path and protection path with acceptable signal quality at the receiver. We propose an impairment aware integer linear programming (ILP) and impairment aware heuristic algorithm that takes into account the PLIs. The ILP provides the optimal solution. It is solved using IBM ILOG CPLEX solver. It is intractable for large size net-work. Therefore we propose the heuristic algorithm for large size network. It is evaluated through discrete-event simulation. But the algorithm provides only the suboptimal solution. To know the performance of this algorithm, the simulation result is compared with the optimal solution. We compute total blocking probability, restoration delay, computation time, and connection setup delay with respect to network load for the heuristic algorithm. We compare the performance of shared-path protection with dedicated-path protection and evaluate the percentage of resource saving of shared-path protection over the dedicated-path protection. In the second and third part of the thesis, we address the issues related to flexible-grid optical networks. In wavelength routed optical network, the bandwidth of each wavelength is fixed and rigid. It supports coarse grained tra c grooming and leads to ancient spectrum utilization. To overcome this, flexible-grid optical networks are proposed. It supports flexible bandwidth, and ne grained tra c groom In the second part of the thesis, we address the routing and spectrum allocation (RSA) algorithm for variable-bit-rate data tra c for flexible-grid optical networks. The RSA problem is NP-complete. Therefore a two-step heuristic approach (routing and spectrum allocation) is proposed to solve the RSA problem. The first step is solved by using a classical shortest path algorithm. For the second step we propose two heuristic schemes for frequency-slot allocation: (i) largest number of free frequency-slot allocation scheme and (ii) largest number of free frequency-slot maintaining scheme. As the network load increases, the spectrum is highly fragmented. To mitigate the fragmentation of the spectrum, we propose a xed-path least-fragmentation heuristic algorithm which fragments the spectrum minimally. It also supports varying-bit-rate tra c and also supports dynamic arrival connection requests. Through extensive simulations the proposed algorithms have been evaluated. Our simulation results show that the algorithms perform better in terms of spectrum utilization, blocking probability, and fraction of fragmentation of the spectrum. The spectrum utilization can reach up to a maximum of 92% and that only 71% of the spectrum is fragmented under maximum network load condition. Finally in the third part of the thesis, we discuss PLIs-aware RSA for the transparent exible-grid optical network. In this network, not only the optical signal expected to travel longer distance, but also to support higher line rates, i.e., data rate is increased up to 1 Tb/s. In such a high data rate, the optical signals are more prone to impairments and noises. As the transmission distance increases, optical signals are subject to tra-verse over many bandwidth-variable wavelength cross connects (BV-WXC) and multiple fibber spans due to which the PLIs get accumulated and are added to the optical signal. These accumulated impairments degrades the signal quality to an unacceptable level at the receiver, the quality of transmission falls below the acceptable threshold value, and the receiver may not be able to detect the signal properly. Therefore our objective is to develop an impairment aware RSA algorithm which establishes the QoT satisfied empathy based on the available resources and the quality of the signal available at the receiver. We formulate the PLIs-RSA problem as an ILP that provides an optimal solution. The optimal solution is obtained by solving the ILP using IBM ILOG CPLEX optimization solver. Since ILP is not efficient for large-size networks, we propose a heuristic algorithm for such a large-size networks. The signal power is measured at the receiver and the connection is established only when the signal power lies above the threshold value. The heuristic algorithm is evaluated through discrete-event simulation. It gives the sub-optimal solution. The simulation result is compared with optimal solution. The result shows that heuristic algorithm performs closer to the ILP. We compute the total blocking probability versus the network load for different spectrum allocation schemes. Total blocking probability is the sum of frequency-slot blocking probability and QoT blocking probability. We compute spectrum efficiency for the proposed algorithm. We also compare our algorithm with the existing routing and spectrum allocation algorithm, and the result shows that our algorithm outperforms the existing algorithms in terms of blocking probability and spectrum utilization.