Search

In this paper, we propose a novel hybrid strategy that combines mixed integer linear programming (MILP) formulation with different alternative routing approaches that is capable of solving, simultaneously, the routing, modulation format and spectrum assignment problem in the design of elastic optical networks. We extend our proposal to a path-link formulation that, although it is not guaranteed to find the optimal solution, it has shown reasonable solutions within inferior simulation time, allowing it to be used in not very short networks. We also compare our proposal with another MILP formulation and three adapted heuristics, all available in the literature. The results show the benefits of our proposal considering diverse simulation scenarios and different number of modulation formats over 19 realistic networks in terms of simulation run time and maximum number of used set of slots.

This work proposes a new Mixed Integer Linear Programming (MILP) formulation for traffic grooming, routing and spectrum allocation to be used in the design of Elastic Optical Networks (EON). In order to compare our method with classic Routing and Spectrum Allocation (RSA) formulation without grooming, the evaluation of the benefits of exact traffic grooming and RSA formulation are presented over three small networks. For each network, the objective function is set as minimizing the maximum slot index among all fibers. Then, the collected results show the benefits of traffic grooming in EON networks. Due to the NP characteristic of the MILP proposed, we propose a heuristic algorithm for large networks, and the benefits of the grooming using this algorithm are investigated.

Spectrum-sliced elastic optical path networks (SLICE) enable flexible bandwidth provisioning, which allows efficient resource utilization and support to heterogeneous bandwidth demands. This makes SLICE a very promising networking architecture. In SLICE, finding a route and a slice of the spectrum is an important design problem, which is known as the Routing and Spectrum Assignment (RSA) problem. In this paper, we present a new heuristic, based on Yen's k-shortest path algorithm and capable of dealing with the traffic heterogeneity to find appropriate sets of paths for each source-destination node pairs to mitigate the bottleneck in the network. The results show that the proposed algorithm reduces the lightpath blocking probability and achieves significantly improved spectrum efficiency. We also analyse the maximum number of alternate shortest paths for minimising the blocking probability.

This paper proposes heuristics, which can maximize the number of remaining available routes and minimize the number of transceivers used in Elastic Optical Networks (EON). The aim of the proposal is to preserve the open capacity for the accommodation of future unknown dynamic demands. Case studies are carried out in order to analyze the performance of the heuristics over two networks. The results suggest that it is feasible to preserve enough open capacity to avoid blocking of future requests in EON with scarce resources.

The performance improvement imparted by routing and spectrum assignment on flexible grid optical networks is a subject of current extensive investigation. Proposed is an efficient spectrum-assignment algorithm based on reducing the loss of capacity of future bandwidth-variable path requests. In all scenarios analysed the proposed algorithm outperformed currently investigated slot assignment algorithms.

Current communication in optical networks presents a wide range of granularities, making it hard to use the optical spectrum efficiently under the WDM framework. In Spectrum Sliced Optical Networks, the WDM rigid frequency grid is replaced by a more flexible structure, in which the spectrum is organized in frequency slots, and each traffic flow is assigned to an appropriate set of contiguous slots. The classical Routing and Wavelength Assignment (RWA) problem is then replaced by a Routing and Spectrum assignment (RSA) problem. This paper addresses an iterativa approach to balance the network load during the routing decision in Spectrum-Elastic Optical Path Networks. We have built numerical examples to illustrate the performance of our routing approach. Comparisons to other routing techniques show that our approach mitigates the lightpath requests blocking probability.