In a Software-Defined Wireless Network (SDWN), Network Function Virtualization (NFV) technology enables implementation of network services using software. These softwarized network services running on NFV nodes, i.e., commercial servers with NFV capability, as virtual machines are called Virtual Network Functions (VNFs). To provide services to users several different VNFs can be configured into one logical chain referred to as a Service Function Chain (SFC). While receiving services from a specific VNF located at an NFV node, a mobile user may change its location. This user may continue to receive service from an associated VNF by routing flows through a new NFV node that is closest to its current location. This may introduce an inefficient routing path which may degrade the network performance. Therefore, it is feasible to relocate the VNFs associated with the service chain of the user to other NFV nodes. To relocate VNFs optimally, we need a new optimal routing path. However, if some NFV nodes on this new path are overloaded, placing these VNFs on overloaded NFV nodes affects the performance of the service chain. To solve this problem, this paper proposes an efficient method for dynamically relocating VNFs by considering changes of a user’s location and the resources currently available at the NFV nodes. The performance of the proposed scheme is evaluated using simulations and an experimental testbed for multiple scenarios under three different network topologies. Results indicate that the proposed scheme balances the load on NFV nodes, reduces SFC blocking rates, and improves the network throughput.

中文翻译：

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动态 VNF 放置以管理软件定义无线网络中的用户流量

在软件定义的无线网络 (SDWN) 中，网络功能虚拟化 (NFV) 技术支持使用软件实现网络服务。这些运行在 NFV 节点上的软件化网络服务，即具有 NFV 功能的商业服务器，作为虚拟机被称为虚拟网络功能 (VNF)。为了向用户提供服务，可以将多个不同的 VNF 配置为一个逻辑链，称为服务功能链 (SFC)。在从位于 NFV 节点的特定 VNF 接收服务时，移动用户可能会改变其位置。该用户可以通过路由流经最接近其当前位置的新 NFV 节点来继续从关联的 VNF 接收服务。这可能会引入可能降低网络性能的低效路由路径。所以，将与用户服务链相关联的 VNF 迁移到其他 NFV 节点是可行的。为了以最佳方式重新定位 VNF，我们需要一个新的最佳路由路径。但是，如果这条新路径上的某些 NFV 节点过载，将这些 VNF 放置在过载的 NFV 节点上会影响服务链的性能。为了解决这个问题，本文提出了一种通过考虑用户位置和NFV节点当前可用资源的变化来动态重新定位VNF的有效方法。所提出的方案的性能是使用模拟和实验测试台在三种不同网络拓扑下的多种场景下进行评估的。结果表明，所提出的方案平衡了 NFV 节点上的负载，降低了 SFC 阻塞率，并提高了网络吞吐量。