## 6 Proposed Methodology
The results of the evaluation were used to set the network performance indices given the traffic workload and network configuration. Sixty Core i7 CPU with 3.40 GHz, 1 IBM Intel server, 8 GB RAM, and Windows 64 bit operating systems were used for evaluation. The experimental topology is presented in the figure. To evaluate the proposed work, two existing models were used: RYU SDN Framework and the detection and mitigating DoS (DDS) [30; 31; 32; 33; 38; 39; 40; 41; 42; 43; 44]. Figure 10 shows the simulation topology. Before analyzing the impact of attacks in an SDN environment, threshold values were set for network components with different parameters. After the attacks were evaluated, these values were compared to obtaining accurate results. The threshold parameters were the CPU utilization, memory utilization, storage space, and throughput [44; 45; 46; 47]. The following Table 2 presents the parameter values recorded before the attack scenario. ## 8 Experiments and Results

The proposed model was evaluated using five parameters: CPU utilization, channel bandwidth, packet delivery ratio, response time, and number of flow requests. CPU utilization is important parameter for evaluating system performance in SDN networks. CPU utilization may vary depending on the deployment of additional security protocols particularly in SDN. This section presents some of the other parameters used to evaluate the proposed scheme. ### A. CPU Utilization

The total CPU processing power was used by ICMP attacks during the attack period. There will be a continuous installation of unwanted requests from the host machine in SDN networks during the attack period. Therefore, in this case, the normal traffic is affected and is only less provisional for trusted requests. The following Figure 11 shows a comparison of CPU utilization for the proposed model with RYU and DDS. The Table 3 presents the CPU utilization based on two sets of evaluation. \begin{table}
\begin{tabular}{l l l} \hline \hline
**S. No** & **Parameter** & **Initial Threshold Values** \\ \hline
1 & CPU utilization & 12\% \\
2 & Memory utilization & 23\% \\
3 & Storage space & 42\% \\
4 & Throughput & 96\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Threshold Value before Analysis. Figure 10: Simulation topology. ### Packet Delivery Ratio

The packet delivery ratio is the ratio of the total packets sent by the source machine to the number of packets received by the destination machine. The packet loss ratio also plays a vital role in evaluating the packet delivery ratio. In our experiment, the TCP packets were sent from the source host to the destination host. The counter is used then to store the number of successful and unsuccessful packets. Table 4 presents the packet ratio units based on two sets of evaluation. The proposed scheme achieved a 98% delivery ratio compared with (87.25%) and DDS (73.25%) as shown in Figure 12. The formula used to calculate the delivery ratio is as follows:

\[FSB=\frac{Data\_Received}{Data-Received+Data\_loss} \tag{3}\] \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline \multirow{2}{*}{**Model**} & \multicolumn{6}{c}{**Packet Delivery (\%)**} \\ \cline{2-10}  & \multicolumn{6}{c}{**Model (Test Run 1)**} & \multicolumn{6}{c}{**Model (Test Run 2)**} \\ \cline{2-10}  & **Sent** & **Delivered** & **Dropped** & **Percentage** & **Sent** & **Delivered** & **Dropped** & **Percentage** \\ \hline RYU & 54,325 & 53,719 & 4557 & 92 & 60,234 & 55,876 & 4358 & 93 \\ DDS & 45,378 & 44,765 & 6161 & 86.4 & 56,236 & 47,235 & 9001 & 84 \\ SPP & 51,123 & 51,109 & 873 & 98.2 & 65,000 & 64,129 & 871 & 98.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Packet Delivery. Figure 11: CPU Utilization. ### Flow Control

Flow requests are vital component of SDN traffic. Because of DoS attacks, more flow rules will be installed by the end switch. Most attacks are executed only with flow request features to overload the SDN controller. The proposed scheme blocks all malicious attacks before they reach the controller.