# Inverse Coupled Simulated Annealing for Enhanced OSPF Convergence in IoT Networks
## 3 Simulation and Evaluation
### Results, Analysis, and Discussion
Compared to the AODV protocol, OSPF-ICSA improves the fault detection accuracy by an average of over 20.19% and 3.1% in the link failure and node failure scenarios, respectively. When compared to the traditional OSPF protocol, the accuracy is increased by an average of over 10.54% and 27.68% in the two scenarios. Additionally, compared to the load centrality (LC) algorithm, OSPF-ICSA's detection accuracy is improved by an average of over 3.56% and 1.14% in the respective scenarios. These results indicate that OSPF-ICSA significantly enhances fault detection accuracy, performing comparably to the BFD algorithm, which achieves faster detection by increasing routing overhead. The advantage of OSPF-ICSA lies in its ability to dynamically adjust the frequency of Hello message transmissions and fault detection times based on real-time feedback from link and node states, thus enabling efficient and flexible fault detection that achieves the same level of precision as the BFD algorithm. Figures 9 and 10 present a comparative analysis of routing overhead for five algorithms under link failure and node failure scenarios across two different network scales. It is evident that the routing overhead of OSPF-ICSA is generally lower than that of other algorithms. In both link failure and node failure scenarios, OSPF-ICSA achieves lower overhead than the AODV protocol under most conditions, with the exception of the larger topology in the node failure scenario, where it is slightly higher than AODV. Compared to the traditional OSPF protocol, OSPF-ICSA reduces overhead by an average of 21.66% and 44.44%, respectively. When compared to the BFD algorithm, OSPF-ICSA decreases overhead by an average of 63.77%. Additionally, it reduces overhead compared to the load centrality (LC) algorithm by an average of 28.14% and 20.47% in the respective scenarios. This can be attributed to two main factors: first, OSPF-ICSA significantly  
Figure 8: Comparison of node failure count vs. fault detection accuracy. Figure 7: Comparison of link failure count vs. fault detection accuracy. shortens fault detection time, enabling nodes in the network topology to quickly sense changes, thus increasing the total amount of successfully transmitted packets compared to traditional OSPF and LC algorithms. Second, OSPF-ICSA dynamically adjusts the frequency of Hello message transmissions, reducing the frequency of Hello messages on normal links and, consequently, lowering the overhead of control messages. In contrast, the BFD algorithm incurs higher routing overhead, partly due to its high frequency of probe message transmissions and partly due to false alarms caused by link jitter and congestion, which further increases routing overhead. Figures 11 and 12 illustrate the comparison of packet delivery rates for five algorithms under link failure and node failure scenarios across two different network scales. It is evident that OSPF-ICSA improves packet delivery rates by an average of 14.04% and 5.1% compared to the AODV protocol in these two scenarios, respectively. When compared to the traditional OSPF protocol, packet delivery rates increase by an average of 34.03% and 153.93%. Furthermore, it is noticeable that the traditional OSPF protocol exhibits poor packet delivery rates during multiple node failures. Additionally, OSPF-ICSA outperforms the load centrality (LC) algorithm, with average increases in packet delivery rates of 15.78% and 28.09% under link failure and node failure scenarios, respectively. However, compared to the BFD algorithm, OSPF-ICSA shows a slight decrease, with reductions of 3.46% and 7.72%. The advantage of OSPF-ICSA in packet delivery rates primarily stems from its ability to perceive changes in network topology and dynamically adjust fault detection times, leading to faster fault diagnosis and LSA flooding. This enables the entire network to detect link failures more swiftly. Although the LC algorithm has optimized fault detection, its response speed remains inferior to that of OSPF-ICSA.