The Software Defined Networks (SDN) is widely used in many industrial and enterprise networking applications due to its flexibility and gaining popularity. It offers various benefits like network virtualization, policy enforcement, greater control, and reduced operational cost. One of the challenging tasks in SDN is to secure the network against the harmful attacks. For this purpose, various attack detection mechanisms are developed in traditional works, which intends to increase the security of SDN by employing different policy enforcement and soft computing techniques. In this paper, a comprehensive survey is presented on various attacks that affect the performance of SDN and its corresponding countermeasure techniques. Typically, the performance of a network can be degraded due to the cause of attacks present on the layers. Also, it leads to reduced Quality of Service (QoS), increased network congestion, and packet drops. So, the attacks present on the layers must be detected or prevented for increasing the performance of SDN. This investigation illustrates various attacks with its causes and the most suitable techniques used for detecting those attacks for improving security. Moreover, the advantages and disadvantages of each attack detection mechanism are presented with its working procedure.

由于软件定义网络（SDN）的灵活性和流行性，它被广泛用于许多工业和企业网络应用中。它具有多种优势，例如网络虚拟化，策略实施，更好的控制和降低的运营成本。SDN中具有挑战性的任务之一是保护网络免受有害攻击。为此，在传统作品中开发了各种攻击检测机制，旨在通过采用不同的策略实施和软计算技术来提高SDN的安全性。本文针对影响SDN性能的各种攻击及其相应的对策技术进行了全面的调查。通常，由于层上存在攻击的原因，网络的性能可能会降低。也，它导致服务质量（QoS）下降，网络拥塞加剧和数据包丢失。因此，必须检测或阻止在层上存在的攻击以提高SDN的性能。此调查说明了各种攻击及其产生原因，以及用于检测这些攻击以提高安全性的最合适技术。此外，还介绍了每种攻击检测机制的优缺点及其工作过程。