Network services in 5G will be rolled out as pools of virtual network functions (VNFs) exploiting the advantages of both software-defined networking and network function virtualization. In this context, 5G network services are envisaged as ordered sequences of VNFs resulting in the so-called VNF Forwarding Graphs (VNFFGs). Such VNFs can be allocated over a number of distributed but interconnected data centers (DCs). In this work, a cloud/network orchestrator is discussed to dynamically process and accommodate VNFFG requests over a pool of DCs interconnected by a multi-layer (packet/flexi-grid optical) transport network infrastructure. Two different cloud and network resource allocation algorithms are proposed aiming at: (1) minimizing the distance between the selected DCs and (2) minimizing the load (i.e., consumed cloud resources) of the chosen DCs. In the performance evaluation, the proposed algorithms are experimentally validated and compared on the CTTC ADRENALINE testbed.

5G网络服务将作为虚拟网络功能（VNF）池推出，从而充分利用软件定义网络和网络功能虚拟化的优势。在这种情况下，将5G网络服务设想为VNF的有序序列，从而产生所谓的VNF转发图（VNFFG）。可以在多个分布式但互连的数据中心（DC）上分配此类VNF。在这项工作中，将讨论云/网络编排器，以动态处理和容纳通过多层（分组/柔性网格）传输网络基础结构互连的DC池上的VNFFG请求。提出了两种不同的云和网络资源分配算法，旨在：（1）最小化所选DC之间的距离，以及（2）最小化负载（即，消耗的云资源）。在性能评估中，对提出的算法进行了实验验证，并在CTTC ADRENALINE测试床上进行了比较。