Passive optical networks (PONs) are an important and interesting technology for broadband access as a result of the growing demand for bandwidth over the past 10 years. An arduous and complex step in the design of such networks involves determining the placement of equipment, optical fiber cables and several other parameters relevant to the proper functioning of the network. In this paper, we propose an evolutionary strategy to optimize the infrastructure design of PONs by using genetic algorithm technique. This meta-heuristic is capable of elaborating fast, automatic and efficient solutions for the design and planning of PONs. Our proposal has been developed using real maps, aiming to minimize deployment costs and time spent to carry out PON projects, achieving pre-defined quality criteria. We considered, in our simulations, two scenarios (non-dense and dense), four possible topologies and two regions of interest. The non-dense consists of a scenario in which subscribers are distributed in a dispersed manner in the region of interest. The dense has a considerably higher number of subscribers distributed in a very close way to each other. Based on the obtained results, the potential of our proposal is quite clear, as well as its relevance from a technical, economic, and commercial point of view.

Network Function Virtualization (NFV), as a promising paradigm, speeds up the service deployment by separating network functions from proprietary devices and deploying them on common servers in the form of software. Any service in NFV-enabled networks is achieved as a Service Function Chain (SFC) which consists of a series of ordered Virtual Network Functions (VNFs). However, migration of VNFs for more flexible services within a dynamic NFV-enabled network is a key challenge to be addressed. Current VNF migration studies mainly focus on single VNF migration decisions without considering the sharing and concurrent migration of VNF instances. In this paper, we assume that each deployed VNF is used by multiple SFCs and deal with the optimal placement for the contemporaneous migration of VNFs based on the actual network situation. We formalize the VNF migration and SFC reconfiguration problem as a mathematical model, which aims to minimize the VNF migration between nodes or the total number of core changes per node. The approach is a two-stage MILP based on optimal order to solve the reconfiguration. Extensive evaluation shows that the proposed approach can reduce the change in terms of location or number of cores per node in a 6-node and 14-node networks while ensuring network latency compared with the model without reconfiguration.

Resource efficiency and survivability are critical concerns in elastic optical networks (EONs) with virtualization. In this paper, we investigate some important aspects in network survivability design against single-link failure under dedicated protection and bandwidth squeezing schemes when multiple virtual topologies are employed. We propose a link-path integer linear programming (ILP) formulation to solve the joint virtualization and survivability problem in elastic optical networks for large network instances, and derive some different types of protection for each virtual topology considering a channel-based spectrum approach to solve the spectrum allocation. Besides, we propose a heuristic to find a pair of predefined paths to ILP formulation aiming to minimize the link load. The proposed ILP and heuristic provide effective survivability solutions and spectrum resource savings for a cooperative design of modern survivable virtualized EONs taking advantages of a link-path model.

Resumo-A 5ª geração de redes móveis (5G), baseadas em redes de acesso de rádio virtualizadas, exigirá soluções econômicas e flexíveis para satisfazer os requisitos de alta taxa de transferência e limites de latência. Uma das principais candidatas para alcançar estes objetivos é a arquitetura de interface "fronthaul". Nessa arquitetura, conhecida Open RAN, que significa "Rede de Acesso de Rádio Aberta" (Open Radio Access Networks) ou (O-RAN), há uma desagregação dos componentes tradicionalmente integrados em uma estação base de celular; as funcionalidades da estação são virtualizadas como funções de rede e divididas ao longo dos nós de rede. Neste artigo, nós abordamos o problema de posicionamento de funções sujeitas à restrições de capacidade e latência em uma arquitetura O-RAN, com o objetivo de minimizar custos de ativação dessas funções. Para tanto, utilizamos um formulação de programação linear inteira (ILP), com caminhos pré-definidos, para modelar o problema de otimização e resolvêlo. Para avaliar a eficácia do método ILP e analisar o desempenho da rede, executamos um amplo conjunto de experimentos em diferentes cenários de rede.