 security of the network. Talking of the SDN functional architecture, we can divide it into 3 parts as: Application Layer: This layer will be used for load balancing, traffic security monitoring etc. Control Layer: This layer is responsible for control commands by the means of controllers like NOX, Flood light etc. (Lau, Rubin, Smith, et al. 2000). Data Layer: This layer consists of routers, virtual switches etc. The security threat can be considered within these three layers as well as interface connecting among these three layers. Open flow vulnerability majorly focuses on transport layer security and Denial of Service (DoS) attacks. Denial of Service Attack: Based on the type of implementation we can divide our denial of service attacks as: Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Analysis of Issues in SDN Security and Solutions Figure 1. SDN functional architecture Application Layer Application - Control Interface Control Layer Control - Data Interface Data layer Layer Distributed Denial of Service Attack: As the name suggested distributed denial of service attack is combined strength of multiple systems work towards a single cause. In this type of attack, a platform is built with many systems which can work under remote commands. In this attack, the attacker hunt for the weakest part of the system within the network by scanning through the network. In this type of attack the attacker once complete the scanning and find the vulnerable host for attack and bring this host under control by software exploitation by means of buffer overflow, code injection etc. Once the sufficient host has been identified that can be brought under control, the attacker create backdoors which will allow special access for future entry. Attackers also update the host and tightens its security SO that no other attackers can use the same host for attack. Thus, for future entry, the attacker will use the back entry that was specially crafted. Low-Rate TCP Targeted Denial of Service: Low-rate