Nabil Naas

Optimum Planning of GMPLS Transport Networks

The rapid increase in the number of wavelengths per fiber has significantly increased the size of the optical crossconnect (OXC) in WDM transport networks. To maintain the scalability of the OXC at a reasonable level, various multi-granular OXC (MG-OXC) architectures have been proposed. Motivated by the fact that the MG-OXC constitutes only the optical segment of the generalized multi-protocol label switching (GMPLS)-based transport node architecture, we first propose a novel node architecture that handles the whole traffic hierarchy defined in GMPLS. Second, incorporating the proposed architecture with our novel contributions, namely (1) bifurcation of multi-granularity traffic demands; (2) traffic flow grouping strategies at all granularity levels, requires defining a new transport planning problem, which we call the routing and multi-granular paths assignment (RMGPA) problem. The RMGPA problem is formulated as a mixed integer linear programming (MILP) model with the objective of minimizing the overall network weighted port count

Towards the realistic planning of GMPLS-based optical transport networks

The multi-granular switching concept defined in Generalized Multiprotocol Label Switching (GMPLS) is expected to be a future-proof solution for mitigating the Optical Crossconnet scalability problems associated with the skyrocketing growth of traffic in optical transport networks. In this paper, we address the problem of planning the GMPLS-based (or multi-granular) transport network with color (or label) conversion and signal regeneration capabilities. The objective of the problem is to minimize the total weighted port count in the transport network. The novelty of this problem lies in the incorporation of the following for the first time: (1) considering all traffic granularities defined in GMPLS; (2) allowing wavelength, waveband, and fiber conversions; (3) considering the optical-reach limitation of optical signals; and (4) customizing the optical reach of all-optical paths. Due to the computational complexity of the problem, we propose various efficient heuristics that are capable of solving large-sized problems in a reasonable amount of time. In order to achieve the best possible solution to the planning problem, a comprehensive evaluation of different heuristic variations through illustrative examples and simulations is conducted. The results also provide valuable insights into many issues that can contribute to further research and development in this area.

Towards optimum planning of GMPLS transport networks

The rapid increase in the number of wavelengths per fiber has significantly increased the size of Optical Crossconnects (OXCs) in WDM transport networks. This calls for the use of Multi-Granular OXCs (MG-OXCs) to maintain the scalability of OXCs at a reasonable level. Various MG-OXC architectures and methods for the planning (or dimensioning) of MG-OXC-based networks have been proposed. Motivated by the fact that the MG-OXC constitutes only the optical segment of GMPLS-based transport node, we first propose a new transport node architecture that can handle the whole traffic hierarchy defined in GMPLS. Second, incorporating the proposed architecture with our novel contributions, namely (1) considering grouping and switching of the whole flows defined in GMPLS; (2) allowing bifurcation of multi-granularity traffic demands among different physical routes, requires defining a new transport planning problem, which we call the Routing and Multi-Granular Paths Assignment (RMGPA) problem. The RMGPA problem is formulated as a Mixed Integer Linear Programming (MILP) model with the objective of minimizing the overall network weighted port count.

Design considerations for energy-efficient Multi-Granular Optical Networks

Multi-Granular Optical Networks (MG-ONs) offer enhanced bandwidth utilization, reduced transmission cost and increased scalability in the optical Internet backbone. There have been several proposals for optimized design of MG-ONs as power consumption in the Internet backbone has recently become an important concern. Although recent research has shown that multi-granular switching concept can guarantee energy savings when compared to the traditional traffic grooming, MG-ON design still calls for legitimate and self-contained design specifications. In this paper, we revisit the Routing and MultiGranular Path Assignment (RMGPA) problem by having the objective of minimized power consumption. Heuristic solutions of RMGPA problem show that crucial power and cost savings can be achieved with the proper selection of the wavelength capacity, waveband size and number of wavebands per fiber with a certain fiber capacity.

Cost-effective heuristics for planning GMPLS-based transport networks

With the ever-increasing traffic in WDM transport networks, the development of GMPLS (or multi-granular) transport networks becomes essential to avoid the cost explosion of OXCs. Much work has been devoted to the development of Multi-Granular Optical Crossconnect (MG-OXC) architectures and network design and planning methods. Extending these efforts here, we address a new problem of planning the GMPLS-based transport network by (1) considering the whole traffic hierarchy defined in GMPLS; and (2) allowing the bifurcation of multi-granularity traffic demands among different physical routes. We call such a problem the Routing and Multi-Granular Paths Assignment (RMGPA). The objective of the problem is to minimize the total weighted port count in the transport network. Due to the computational complexity of the problem, only very small-sized planning problems can be solved exactly through Mixed Integer Linear Programming (MILP) optimization. In this paper, we propose efficient heuristics that are capable of solving large-sized planning problems in a reasonable amount of time.

Energy-efficient DBA and QoS in FiWi networks constrained to metro-access convergence

Fiber-Wireless (FiWi) access networks aim at combining the flexibility, ubiquity and mobility of wireless access networks with the robustness and high capacity support of the optical access networks. Several bandwidth allocation algorithms have been proposed for the convergence of fiber and wireless access networks. Besides, fiber-wireless convergence, metro-access convergence and energy-efficiency have appeared as further challenges of the ICTs. In this paper, we report our current research results on the service quality of existing energy-efficient bandwidth allocation schemes in long-reach FiWi networks, in terms of detailed delay performance, fairness and utilization. We show that deployment of energy-efficient Dynamic Bandwidth Allocation (DBA) in a FiWi network does not only guarantee energy savings throughout the day but also introduces reduced maximum packet delay for both FTTX and wireless users, enhanced delay variance for all packets and significant fairness among different parts of the network. Furthermore, energy-efficient DBA decreases average buffer occupancy at the ONUs.

Power and cost reduction in optical transport networks by Multi-Granular switching with optical reach consideration

Multi-Granular (MG) switching concept has emerged as a strong candidate to alleviate the scalability problems of the conventional optical switching that will result from the expected exponential traffic growth in the optical transport networks. On the other hand, this tremendous increase in the bandwidth demands will also introduce the energy bottleneck in the transport networks. Furthermore, significant contribution of the telecommunication networks to the Greenhouse Gas Emissions (GGE) has appeared as another challenge to be met in network design and planning policies. In this paper, considering the benefits of MG switching in the optical backbone, we study the benefit of employing the MG switching concept in the transport networks in terms of energy savings. Under various scenarios, our numerical results present realistic design specifications for MG optical transport networks by efficiently integrating the optical reach limitation into the design and planning problem.

Heuristics for Planning GMPLS Networks with Conversion and Regeneration Capabilities

With the explosive traffic growth of WDM-based transport networks, the development of GMPLS (or multi- granularity)-based transport networks becomes essential to cope with the network scalability problems. This paper defines a novel problem of planning realistic GMPLS-based transport networks by (1) considering the whole traffic hierarchy defined in GMPLS; (2) allowing optical signal conversion at all granularity levels; (3) imposing optical reach constraint on the length of all- optical paths. We will call such a problem the routing and multi- granular paths assignment (RMGPA). The objective of the problem is to minimize the weighted port count in the transport network. Due to the computational complexity of the problem, only very-small-sized problems can be solved exactly through mixed integer linear programming (MILP) optimization. In this work, we propose novel heuristics that are capable of solving large-sized problems in a reasonable amount of time.

Energy-efficient design for multi-granular optical transport networks with optical reach consideration

Abstract Energy consumption of the optical backbone is expected to contribute to a significant portion of the energy consumed by the telecommunication networks. As an enhanced bandwidth utilization and management extent of the optical Wavelength Division Multiplexing (WDM) technology, multi-granular switching concept has been shown to guarantee energy savings when compared to the traditional traffic grooming. However, Multi-Granular Optical Transport Network (MG-OTN) design and planning still calls for legitimate and self-contained design specifications. In this paper, we revisit the Routing and Multi-Granular Path Assignment (RMGPA) problem by having the objective of minimized power consumption and integrating the optical reach limitation of optical signals in the design and planning problem. The new problem is formulated as a Mixed Integer Linear Programming (MILP) model. For large scale design scenarios, we propose an efficient heuristic approach that is capable of solving the power minimization problem in feasible runtime. The heuristics is verified within 2% average approximation to the MILP solutions under small scale scenarios, and the numerical results of the design and planning problem heuristic show that significant power savings up to 55% in MG-OTNs can be achieved with the proper selection of the wavelength capacity, waveband size, number of wavebands per fiber, and the value of the optical reach. Furthermore, the proposed heuristic has been shown to guarantee high fairness among the nodes with respect to the power fairness index, which is at the order of 92–99% under various traffic scenarios.

Energy-efficient realistic design and planning of optical backbone with multi-granular switching

Energy consumption of the core networks is expected to contribute to a significant portion of the energy consumed by the telecommunication networks. Besides their high capacity and reliability advantages, optical networks have also emerged as promising technologies to ensure energy-efficiency in the core Internet. As an enhanced bandwidth utilization and management extent of the optical WDM technology, multi-granular switching concept has been shown to guarantee further energy savings when compared to the traditional traffic grooming. In this paper, we revisit the Routing and Multi-Granular Path Assignment (RMGPA) problem by having the objective of minimized power consumption and integrating the optical-reach limitation of optical signals in the design and planning. We explain the heuristic optimization approach used to solve the revisited problem. With the use of this heuristic, we present the design and planning for different optical backbone topologies using the multi-granular switching technology to demonstrate, analyze, and give insights on the impact of optical reach on the power consumption of the optical backbone.