Network Function Virtualization (NFV) has emerged as an innovative network architecture paradigm that uses IT virtualization technology to abstract the network node functions from hardware. The virtualized network services hosted on Virtual Machines (VMs) are called Virtual Network Functions (VNFs). The sequence of multiple VNFs required by network operators to perform traffic steering is called a Service Function Chain (SFC). Software Defined Networking (SDN) is a complementary technology which allows programmatic control of network functions and policy-based resource management. The flexibility of SDN facilitates structuring of SFCs with minimum latency. SFC provisioning using SDN and NFV will enable implementation of next generation 5G networks and make the subscriber/operator relationship more economical and flexible. In this paper, a Systematic Literature Review (SLR) is used to select the high-quality research studies related to dynamic provisioning of SFCs in SDN and NFV. A total of 70 studies available in the literature are analyzed. Thereafter, a layered taxonomy is proposed to classify the literature based on the parameters of optimization approaches for the provisioning of SFCs. Finally, the open research challenges for SFC deployment are identified and discussed. This paper is intended to serve as a ready reference for the research community to develop effective and efficient techniques for SFC provisioning in combined SDN/NFV networks by considering a combination of multiple factors viz. placement of VNFs, load balancing, and availability. It will surely aid Cloud Service Providers (CSPs), Application Service Providers (ASPs), and Internet Service Providers (ISPs) in offering reliable, scalable and high-performance services to their customers.

网络功能虚拟化（NFV）已成为一种创新的网络体系结构范例，该范式使用IT虚拟化技术从硬件中提取网络节点功能。托管在虚拟机（VM）上的虚拟化网络服务称为虚拟网络功能（VNF）。网络运营商执行流量控制所需的多个VNF的顺序称为服务功能链（SFC）。软件定义网络（SDN）是一项补充技术，允许对网络功能和基于策略的资源管理进行程序控制。SDN的灵活性有助于以最小的延迟构建SFC。使用SDN和NFV进行SFC设置将能够实现下一代5G网络，并使订户/运营商关系更加经济和灵活。在本文中，系统文献综述（SLR）用于选择与SDN和NFV中SFC的动态配置有关的高质量研究。分析了文献中共有70项研究。此后，提出了一种分层分类法，以基于提供SFC的优化方法的参数对文献进行分类。最后，确定并讨论了SFC部署的公开研究挑战。本文旨在通过考虑多种因素的组合，为研究界开发有效的高效技术，以在组合的SDN / NFV网络中开发SFC设置提供参考。VNF的放置，负载平衡和可用性。它将肯定会帮助云服务提供商（CSP），应用程序服务提供商（ASP），