# An Efficient Network Resource Management in SDN for Cloud Services
## 5 Performance Evaluation  
In this section, we evaluate the performance of the network management method based on the ranking table that is applied to a cloud system in an SDN environment. As a result that it is difficult to collect the input data for the experiment from actual cloud-based services, we obtained them through the Ostinato [18] packet generator by analyzing the user request patterns. Tables 1 and 2 show the settings used for the system and the experimental data applied during the experiments, respectively. The data used for the experiment are largely divided into multimedia and web service data. All the data have 180 flows. The packet size for the web service is generated randomly. It is assumed that the service request pattern of the web data is a random request made again within 10 min of an incoming request. Figure 5 shows the network topology used for the experiments. The topology consists of eight switches and sends data traffic through four network paths. The cost of each link is 1. Hence, the total cost of each network path is the number of hops composing the path. Hence, the network paths s1-s2-s8 and s1-s3-s8 are better than network paths s1-s4-s6-s8 and s1-s5-s7-s8. It is assumed that the paths s1-s2-s8 and s1-s3-s8 do not include more than 60 flows each. Therefore, not all flows can use the optimal paths. Some of them have to use the non-optimal paths s1-s4-s6-s8 and s1-s5-s7-s8. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline SDN controller & ONOS 1.3 \\ Simulator & Mininet 2.2 \\ OS & Linux Ubuntu 14.0 \\ Language & JAVA \\ Packet generator & Ostinato 0.5.1 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The system configuration for the experiments. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Service Type** & **Content Type** & **Traffic Pattern** \\ \hline \multirow{3}{*}{Multimedia service} & Video downloading & 300 MB–1 GB \\  & Video streaming & 240 KB, 360 KB, 720 KB, 1 MB, 2 MB \\  & Video encoding & 5 GB–15 GB \\ \hline \multirow{3}{*}{Web service} & Web page loading & 1 MB–15 MB \\  & Image loading & 1 MB–10 MB \\ \cline{1-1}  & Metadata loading & 0.1 MB–1 MB \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The data configuration for the experiments. Figure 4: Network path allocation procedure using the ranking table in the application. Figure 6 shows the data workloads used for the experiment, which have six workload types. Each workload represents the number of multimedia and web services requested over time. In the figure, the amount of data for multimedia and web services is the same for both Workload-E and the Workload-F. In this study, we evaluated the performance of the six workload types in the experiments. These experiments aim to verify how much data traffic is transmitted through optimal paths by efficiently allocating the network resources to the service flow. For performance comparison, we also implemented the OSPF, which is the most commonly used in the conventional path selection algorithms. Many researchers have investigated its performance in the SDN environment [12; 13] and compared their proposals with the OSPF [14]. In our study, we also evaluate the OSPF and compare it with our proposed algorithm. In the experiments, we set the weighting factor \(\alpha\) of our proposed method as 0.5. We also update the ranking table every 5 min and distribute the flow rules to the switches at the same frequency. Figure 7 shows the performance evaluation results for Workload-A in which the multimedia services increase and the web services decrease. The vertical axis indicates the network utilization, and the horizontal axis indicates the flow of time in minutes. The network utilization is the amount of data sent divided by the maximum amount of data that can be sent through the optimal paths. This shows how many data are sent through the network paths. In the experiments, up to 120 flows can be sent through the optimal paths and the measurement interval is 5 min.