Software-defined datacenters (SDDCs) have recently received much attention for rapid delivery of cloud-based applications. In this paper, we consider the design of an optical aggregation network for cost-efficient software-defined datacenters (SDDCs). Here, an optical aggregation network connects a server accommodating virtual network functions (VNFs) with access gateway nodes (AGNs) via a time-division-multiplexing (TDM)-based point-to-multipoint (P2MP) wavelength path to aggregate traffic from geographically distributed end users to cloud datacenters. Each VNF must be placed on an adequate server in consideration of the efficiency of wavelength paths to reduce network cost for cloud access. However, existing VNF placement algorithms determine VNF placement without considering the efficiency of wavelength paths, which deteriorates network performance and increases network cost. To solve this problem, VNFs must be placed so that a P2MP wavelength path can be efficiently shared by multiple AGNs to reduce network cost. For this purpose, we propose a VNF placement algorithm, called the decomposition-based VNF placement algorithm (DVA), in a TDM-wavelength-division-multiplexing (WDM)-based optical aggregation network for cost-efficient SDDCs. DVA can find approximate solutions of sufficient quality within practical computation time.

最近，软件定义的数据中心（SDDC）在基于云的应用程序的快速交付方面备受关注。在本文中，我们考虑为经济高效的软件定义数据中心（SDDC）设计光聚合网络。在此，光聚合网络通过基于时分复用（TDM）的点对多点（P2MP）波长路径将容纳虚拟网络功能（VNF）的服务器与接入网关节点（AGN）连接，以聚合来自地理位置的流量将最终用户分散到云数据中心。考虑到波长路径的效率，必须将每个VNF放在适当的服务器上，以减少用于云访问的网络成本。但是，现有的VNF放置算法可以在不考虑波长路径效率的情况下确定VNF放置，这会降低网络性能并增加网络成本。为了解决此问题，必须放置VNF，以便多个AGN可以有效共享P2MP波长路径，以降低网络成本。为此，我们在基于TDM波分复用（WDM）的光聚合网络中提出了一种基于VDM的VNF放置算法，称为基于分解的VNF放置算法（DVA），用于具有成本效益的SDDC。DVA可以在实际计算时间内找到足够质量的近似解决方案。在基于TDM的波分复用（WDM）的光聚合网络中实现低成本SDDC。DVA可以在实际计算时间内找到足够质量的近似解决方案。在基于TDM的波分复用（WDM）的光聚合网络中实现低成本SDDC。DVA可以在实际计算时间内找到足够质量的近似解决方案。