## 4 Simulation and Evaluation
### Delay Measurement  
In our experiments, we measured the delay using Equation (1). Equation (1) shows that the delay was a combination of propagation, transmission, and querying delay. In Equation (1), the \(PD\) is the propagation delay, \(TD\) is the transmission delay, and \(QD\) is the querying delay. Hence, the total delay \(D\) is affected by these three factors contributing to delay. Further information to calculate the \(PD\), \(TD\), and \(QD\) is given in [36]. For sending the packets to the receiver we have used Mini-net and the Iperf tool [37]. Through Iperf we started a client and server on the sending and receiving hosts. Moreover, we recorded the time (ms) according to the Equation (1). Figure 7 shows the delay of handover scenarios in single, multi-controller, inter- and intra-domain for SDN, NDN, and the proposed strategy (category 1 to 4). We can see that the delay with single controller category \(1\) is lower because of the involvement of a single controller. However, the delay increases with more controllers are mobile, i.e., from category 1 to category 4. The proposed architecture leverages the global view of the SDN and proactive measurements for transmission of packets resulting in a decrease in delay as compared to other schemes. We can also see that the delay in [25] is less than in the scheme of [26], because they present scheme for mobility with a preprocess that benefits from being connectionless. It also benefits from a multi-path mechanism for packet forwarding in NDN to produce a forwarding path with future interest in advance, that helps the producer in performing handover with less delay as compared to [26]. \[D=PD+TD+QD \tag{1}\]  
B. Throughput Measurement  
The throughput is obtained by leveraging the Iperf tool. Throughput (T) is defined in Equation (2), i.e., the number of packets sent in unit time (t). In Equation (2), the Pi shows the packet, and the N is the total number of packets in unit time (t). We have recovered it over a period of 500 s. To execute the experiment, we have opened two hosts in the network and started the client server communication using Iperf. Iperf is mostly used to measure the throughput, i.e., the number of packets sent in a unit of time from the client to the server. We measured the throughput of the SDN, NDN, and our proposed architecture leveraging SDN. Herein, the throughput is recorded for 500 s. Figure 8 shows the throughput comparison in various handover scenarios. For measuring the throughput, we used the Iperf tool and started a client and server sockets on the two hosts. Then, we started sending the packets from the client toward the server host on the listening socket. From Figure 8,  
Figure 7: Comparison of the delay time with previous works [25] ([PERSON], 2017) and [26] given by ([PERSON], 2017). we can see that the proposed architecture has a global view provision for handover during mobility and, thus, the throughput is high as compared to [25] and [26]. The proactive caching as discussed in our scheme and the global perspective of SDN contribute to the improved throughput in comparison with other schemes. However, category 1, employing less movement, has increased throughput because of the low packet loss rate due to low mobility. In addition, the provisioning of services in [25] contributes to a higher throughput as compared to [26]. \[T=\frac{\sum_{i}^{N}Pi}{t} \tag{2}\]  
C. CPU Utilization  
CPU usage refers to the workload that a CPU handles or the processing resources that a computer uses. The sysbench tool [38] is used to measure CPU utilization. The actual CPU usage is influenced by the amount and type of computing tasks managed by the system. The y-axis of the graph displays CPU usage as a percentage. CPU time (CT) is defined as the time amount that the process takes while utilizing the CPU. Moreover, the percentage conversion is performed via dividing it over the real time passed. Suppose if the CPU time calculated is 1 s out of total time for execution, i.e., 4 s, the CPU utilization will be \(1/4\times 100=25\%\).