Metropolitan networks are undergoing a major technological breakthrough leveraging the capabilities of software-defined networking (SDN) and network function virtualization (NFV). NFV permits the deployment of virtualized network functions (VNFs) on commodity hardware appliances which can be combined with SDN flexibility and programmability of the network infrastructure. SDN/NFV-enabled networks require decision-making in two time scales: short-term online resource allocation and mid-to-long term offline planning. In this paper, we first tackle the dimensioning of SDN/NFV-enabled metropolitan networks paying special attention to the role that latency plays in the capacity planning. We focus on a specific use-case: the metropolitan network that covers the Murcia - Alicante Spanish regions. Then, we propose a latency-aware multilayer service-chain allocation (LA-ML-SCA) algorithm to explore a range of maximum latency requirements and their impact on the resources for dimensioning the metropolitan network. We observe that design costs increase for low latency requirements as more data center facilities need to be spread to get closer to the network edge, reducing the economies of scale on the IT infrastructure. Subsequently, we review our recent joint computation of multi-site VNF placement and multilayer resource allocation in the deployment of a network service in a metro network. Specifically, a set of subroutines contained in LA-ML-SCA are experimentally validated in a network optimization-as-a-service architecture that assists an Open-Source MANO instance, virtual infrastructure managers and WAN controllers in a metro network test-bed.

中文翻译：

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城域网IT与多层在线资源配置与线下规划

利用软件定义网络 (SDN) 和网络功能虚拟化 (NFV) 的功能，城域网正在经历重大技术突破。NFV 允许在商用硬件设备上部署虚拟化网络功能 (VNF)，这可以与网络基础设施的 SDN 灵活性和可编程性相结合。支持SDN/NFV的网络需要在两个时间尺度上进行决策：短期在线资源分配和中长期离线规划。在本文中，我们首先解决了支持 SDN/NFV 的城域网络的维度，特别关注延迟在容量规划中的作用。我们专注于一个特定的用例：覆盖穆尔西亚 - 阿利坎特西班牙地区的城市网络。然后，我们提出了一种延迟感知多层服务链分配 (LA-ML-SCA) 算法，以探索一系列最大延迟要求及其对确定城域网络规模的资源的影响。我们观察到，随着需要扩展更多数据中心设施以接近网络边缘，降低了 IT 基础设施的规模经济，低延迟要求的设计成本会增加。随后，我们回顾了我们最近在城域网中部署网络服务时对多站点 VNF 放置和多层资源分配的联合计算。具体来说，LA-ML-SCA 中包含的一组子例程在网络优化即服务架构中进行了实验验证，该架构协助城域网测试台中的开源 MANO 实例、虚拟基础设施管理器和 WAN 控制器。