## 6 Performance Evaluation  
The performance of the Thread network was analyzed by conducting different experiments using the iperf testing tool. To measure the network's performance, iperf uses a server and client structure. This tool can provide detailed information about the network's behavior. The metrics used for performance evaluation are as follows:  
* **Jitter**: It is the variation in time for a packet to travel across a network and is usually measured in milliseconds (ms). A high jitter negatively impacts network performance and causes irregularities in data transfers. This degraded quality of service is highly undesirable, especially for real-time applications, such as voice and video communications, where a consistent and predictable delay is crucial. * **Packet loss ratio**: Furthermore, known as packet drop ratio, represents the number of lost packets to the total number of packets sent. It represents the percentage of packets that did not reach their intended destination due to various network issues. It is an  
Figure 8: Topology 2 : OpenThread web interface. Figure 9: Topology 3: OpenThread web interface. important metric to evaluate the reliability and performance of a network. Its higher percentage means loss of data and reflects degraded network performance. * **Round Trip Time**: It refers to the time taken for a packet to travel from a source to a destination and then back to the source, measured in milliseconds (ms). It is considered an important metric in networking to measure the quality of a network and is commonly used to diagnose the reliability of the network. A long RTT in a network is undesirable and can negatively impact the performance of real-time applications. While jitter is often associated with RTT and packet loss, in this paper, we treat it as an independent parameter to analyze its impact on the network performance. It is important to note that their behavior is interrelated. When network delays are stable and consistent, the RTT tends to be low, indicating efficient packet delivery and low jitter. Conversely, if the network delays exhibit variability and fluctuations, the RTT will be high, leading to increased jitter. High jitter, in turn, can elevate the probability of packet loss. Consequently, understanding and analyzing jitter as a separate parameter enables us to gain insights into the network's stability, consistency, and overall quality of service. We conducted different experiments for UDP traffic, where each experiment had a different scenario for varying bitrate and payload size. The details of the experimental scenarios can be found below:  
* **Varying Network Topology** To assess the scalability of a network and gauge its performance as it expands, we generate diverse network topologies by modifying the number of devices and their assigned roles. This enables us to examine the network's capacity for growth and measure the effects on the network's performance after changing the roles of individual devices. * **Varying Payload Size** We conduct a network performance analysis by varying the payload size. This enables us to measure the jitter and packet loss ratio against each communication. * **Varying Bitrate** We conduct a performance analysis of the network by varying the bitrate, enabling us to observe and evaluate the network's performance under these modified conditions. * **Link Failure** To check the robustness of the network, link failure was introduced between a router and a leader. Traffic was generated in the topology to check the network response to link failure. In our experiments, we have configured the network by varying the bitrate and payload size. The UDP packet size is 1208 bytes by default and 250 kbps is the theoretical maximum data rate provided by Thread, however, we conducted experiments by systematically varying the metrics, as presented in Table 3. This section is divided into several subsections, each discussing specific experiments that aim to analyze and evaluate different aspects of network performance under various scenarios.