# Fast Reroute Mechanism for Satellite Networks Based on Segment Routing and Dual Timers Switching
## 4 Performance Evaluation
### Simulation Results  
The comparison results for the fault scenario A in Figures 4 and 5, showing the routing recovery times and primary-backup path switch counts, are presented in the figure. It is observed that the SRDT-FRR scheme and Scheme 3 recover from faults within approximately 100 ms, with primary-backup path switching times around 10 ms, resulting in lower routing interruption times. In contrast, the other schemes take about 3100 ms for routing recovery, with recalculated routing times around 50 ms, leading to longer routing interruption times. Additionally, the impact score results in Table 1 show that SRDT-FRR has the smallest impact score, further demonstrating its superior performance. Table 2 indicates that there is variability in the impact scores, which can be attributed to the uncontrollable time interval between the occurrence of a fault and its detection during the experiment. For instance, hardware monitoring detects faults occurring every 50 ms, while the fault could occur at any time between 0 and 50 ms, resulting in fluctuations in the routing interruption time. Consequently, this leads to variability in the impact scores. Figure 4: Routing interruption time results for fault scenario A.  
Figure 5: Primary-backup path switching results for fault scenario A. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**FRR Methods** & **Experiment 1** & **Experiment 2** & **Experiment 3** & **Experiment 4** \\ \hline Proposed SRDT-FRR & 0.102033 & 0.109003 & 0.101162 & 0.100000 \\ BP-LSRFD & 0.969797 & 0.974443 & 0.944821 & 0.970958 \\ BP-BFD & 0.103485 & 0.109003 & 0.102904 & 0.102033 \\ baseline SS-FRR & 0.963117 & 0.969797 & 0.965150 & 0.967183 \\ LSRFD & 0.884608 & 0.890707 & 0.888093 & 0.900000 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The impact scores for fault scenario A. In fault scenario C, the comparison results in Figures 8 and 9 indicate that the SRDT-FRR scheme effectively detects transient faults, recovering from faults in about 100 ms, while the other schemes experience routing interruption times exceeding 10 s. Moreover, as shown in Table 5, SRDT-FRR yields the lowest impact score, underscoring its outstanding performance. In Table 6, the \(p\)-values are all less than 0.001, indicating that there are significant differences in the routing interruption time and switching overhead between the \"Proposed SRDT-FRR\" and the other strategies. The simulation time for the above experiments was set to 6000 s, and the link failures in the three fault scenarios were randomly configured. Therefore, the simulation results of the different schemes are not significantly influenced by the simulation duration. To further validate the analysis from an experimental perspective, we extended the simulation time to 60,000 s and re-simulated the routing interruption times of each scheme under fault scenario A. Comparing the results shown in Figure 10 with those in Figure 4, it is evident that there is almost no difference between the two, which further supports the validity of our previous analysis. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**FRR Methods** & **Mean** & **Standard Deviation** & \(\mathbf{p}\)**-Value with Proposed SRDT-FRR** \\ \hline Proposed SRDT-FRR & 0.051667 & 0.001188 & / \\ BP-LSRFD & 0.880935 & 0.039263 & \textless{}0.001 \\ BP-BFD & 0.102088 & 0.001720 & \textless{}0.001 \\ baseline SS-FRR & 0.902993 & 0.003356 & \textless{}0.001 \\ LSRFD & 0.894010 & 0.007390 & \textless{}0.001 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Statistical significance of impact scores for fault scenario C.