Software-defined networking (SDN) is a new paradigm that consists in decoupling the control plane from the data plane, which offers the flexibility of configuring and managing networks. Recently, an extension of SDN to vehicular ad hoc networks (VANETs), named software-defined vehicular networks (SDVN), has been emerged to expand the capabilities of VANET in terms of the provided services and to overcome the VANET issues. Also, SDN has gained a lot of interest to be involved in the extensions of VANET, which are vehicular cloud and vehicular fog. In this paper, we overview the use of SDN in VANET. We survey its deployment in the classic vehicular networks, 5G-VANET, vehicular cloud, and vehicular fog. Thereafter, we discuss some case studies of SDN in the vehicular context. Then, we present a taxonomy of the existing architectures followed by the major challenges in the implementation of SDN in the vehicular context. Next, we review the tools used to simulate SDN-based VANET scenarios. Finally, we give some future research directions.

中文翻译：

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车载网络中的软件定义网络：一项调查

软件定义网络 (SDN) 是一种新的范式，它包括将控制平面与数据平面解耦，从而提供配置和管理网络的灵活性。最近，出现了将 SDN 扩展到车载自组织网络 (VANET)，称为软件定义车载网络 (SDVN)，以扩展 VANET 在提供服务方面的能力并克服 VANET 问题。此外，SDN 对参与 VANET 的扩展产生了很大的兴趣，即车载云和车载雾。在本文中，我们概述了 SDN 在 VANET 中的使用。我们调查了它在经典车载网络、5G-VANET、车载云和车载雾中的部署。此后，我们讨论了车载环境中 SDN 的一些案例研究。然后，我们对现有架构进行了分类，然后介绍了在车辆环境中实施 SDN 的主要挑战。接下来，我们回顾了用于模拟基于 SDN 的 VANET 场景的工具。最后，我们给出了一些未来的研究方向。