Network function virtualization is an emerging concept that is attracting increasing attention in the industry because it offers high levels of agility and flexibility to the network allowing easier software updates, resource adjustment and scalable changes in the configuration of the services. Network functions traditionally delivered on hardware and purpose-built platforms in legacy networks can now be provided through shared virtual resources called VNFs (Virtual network functions) hosted over shared physical network infrastructures. Using network functions as absolute software components would certainly improve the deployment process and the management of the VNF life cycle. Since VNFs are hardware-independent, there is no need to check whether or not a network function is compatible with the rest of the network's physical parts; this also helps reduce the maintenance costs, which can increase drastically in the case of major upgrades to the network infrastructure. Along with all these benefits, shifting to virtual-based networks comes with a significant number of challenges, especially in terms of placing such virtual components, ensuring their interoperability and maintaining the quality of service at a level that is at least as good as what is offered by hardware based architectures. In this paper, we propose a cluster-based placement and chaining solution. The overall proposed approach consists of: 1) formulating an Integer Linear Programming (ILP) model aimed at finding an optimal tradeoff between multiple objective functions that might be sometimes conflicting (e.g hardware resource and energy consumption minimization, transmission delays, bandwidth usage, etc…), 2) classifying the substrate network into a set of on-demand clusters that are efficient for a predefined set of metrics, and 3) using meta-heuristic-based algorithms to find near-optimal solutions for the formulated ILP.

网络功能虚拟化是一个新兴的概念，在业界引起了越来越多的关注，因为它为网络提供了高度的敏捷性和灵活性，允许更轻松的软件更新，资源调整和服务配置的可扩展更改。现在，可以通过在共享物理网络基础结构上托管的称为VNF（虚拟网络功能）的共享虚拟资源，来提供传统网络在传统网络上的硬件和专用平台上交付的网络功能。将网络功能用作绝对软件组件肯定会改善部署过程和VNF生命周期的管理。由于VNF与硬件无关，因此无需检查网络功能是否与网络其余物理部分兼容。这也有助于降低维护成本，如果对网络基础架构进行重大升级，维护成本可能会急剧增加。除了所有这些好处之外，向基于虚拟的网络过渡还带来许多挑战，尤其是在放置此类虚拟组件，确保它们的互操作性以及将服务质量维持在至少与现有水平相当的水平方面。由基于硬件的体系结构提供。在本文中，我们提出了一种基于群集的放置和链接解决方案。总体建议的方法包括：1）建立一个整数线性规划（ILP）模型，旨在找到有时可能会冲突的多个目标函数之间的最佳权衡（例如，硬件资源和能耗最小化，传输延迟，带宽使用等）。 ），